Three oral doses of ~3x10^6 cfu WRSS1(12 participants) or placebo (4 participants)

Adverse event (AE) was defined as any untoward medical occurrence in humans, whether or not considered drug related, that occurs during the conduct of a clinical trial. A Serious Adverse Event (SAE) , including serious suspected adverse reaction or serious adverse reaction as determined by the Investigator or the sponsor, was any event that results in any of the following outcomes: Inpatient hospitalization or prolongation of existing hospitalization , life-threatening AE that in the opinion of the investigator or sponsor put the participant at immediate risk of death, persistent or significant incapacity or substantial disruption, congenital abnormality or birth defect, a medically important event that may have jeopardized the participant or may have required intervention to prevent one of the other outcomes listed or death. Causality of the AE/SAE to the study drug was assessed by the Investigator as reasonable possibility that the study product caused the reported event.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgA responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgA responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer..

The mucosal immune response to WRSS1 was evaluated by assessing specific IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgA responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The mucosal immune response to WRSS1 was evaluated by assessing specific immunoglobulin G (IgG ) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgG responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgG responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgG (immunoglobulin G) antibody responses to S. sonnei 2a Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine Invaplex-specific IgG responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS-specific IgG responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgG responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The mucosal immune response to WRSS1 was evaluated by assessing specific immunoglobulin M (IgM) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgM responses from circulating lymphocytes. Proportion of children with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgM (immunoglobulin M) antibody responses to S. sonnei 2a Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine Invaplex-specific IgM responses from circulating lymphocytes. Proportion of children with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgM (immunoglobulin M) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- specific IgM responses from circulating lymphocytes. Proportion of children with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgM (immunoglobulin M) antibody responses to S. sonnei 2a Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine Invaplex-specific IgM responses from circulating lymphocytes. Proportion of children with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgM (immunoglobulin M) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS-specific IgM responses from circulating lymphocytes. Proportion of children with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgM (immunoglobulin M) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgM responses from circulating lymphocytes. Proportion of children with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgM (immunoglobulin M) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgM (immunoglobulin M) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgM (immunoglobulin M) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgM (immunoglobulin M) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgM (immunoglobulin M) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgM (immunoglobulin M) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The systemic immune response to WRSS1 was evaluated by assessing the IgM (immunoglobulin M) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

Antibody Secreting Cell (ASC) by ELISPOT assay responses for IgA (immunoglobulin A) and IgG (immunoglobulin B) ASCs specific for LPS (lipopolysaccharide) and Invaplex were determined at Days -1, 7, 35, and 63. 2-fold increases of LPS and Invaplex specific IgA and IgG in ASC beyond baseline mean + 3 Standard Deviation (SD) were determined. Positive response was ≥8 spots per 1 million peripheral blood mononuclear cells.

Antibody Secreting Cell (ASC) by ELISPOT assay responses for IgA (immunoglobulin A) and IgG (immunoglobulin B) ASCs specific for LPS (lipopolysaccharide) and Invaplex were determined at Days -1, 7, 35, and 63. 2-fold increases of LPS and Invaplex specific IgA and IgG in ASC beyond baseline mean + 3 Standard Deviation (SD) were determined. Positive response was ≥8 spots per 1 million peripheral blood mononuclear cells.

Antibody Secreting Cell (ASC) by ELISPOT assay responses for IgA (immunoglobulin A) and IgG (immunoglobulin B) ASCs specific for LPS (lipopolysaccharide) and Invaplex were determined at Days -1, 7, 35, and 63. 2-fold increases of LPS and Invaplex specific IgA and IgG in ASC beyond baseline mean + 3 Standard Deviation (SD) were determined. Positive response was ≥8 spots per 1 million peripheral blood mononuclear cells.

Antibody Secreting Cell (ASC) by ELISPOT assay responses for IgA (immunoglobulin A) and IgG (immunoglobulin B) ASCs specific for LPS (lipopolysaccharide) and Invaplex were determined at Days -1, 7, 35, and 63. 2-fold increases of LPS and Invaplex specific IgA and IgG in ASC beyond baseline mean + 3 Standard Deviation (SD) were determined. Positive response was ≥8 spots per 1 million peripheral blood mononuclear cells.

The mucosal immune response to the WRSS1 was evaluated by assessing Fecal IgA (immunoglobulin A) antibody responses in stool to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in enzyme-linked immunosorbent assay (ELISA) assays, at Days -1, 7, 28, 35, 56, 63, and 84. 4-fold increases of LPS and invaplex-specific IgA in stool beyond baseline mean + 3 SD (standard deviation) were determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer. Pro-inflammatory cytokines (Interleukin 1 beta (IL-1β), Interleukin 8 (IL-8), tumor necrosis factor alpha (TNF-α) and Interferon gamma (IFN-γ)) were measured in stool extracts using commercially available ELISA kits.

The mucosal immune response to the WRSS1 was evaluated by assessing Fecal IgA (immunoglobulin A) antibody responses in stool to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in ELISA assays, at Days -1, 7, 28, 35, 56, 63, and 84. 4-fold increases of LPS and invaplex-specific IgA in stool beyond baseline mean + 3 SD (standard deviation) were determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.Pro-inflammatory cytokines (IL-1β, IL-8, TNF-α and IFN-γ) were measured in stool extracts using commercially available ELISA kits.

The mucosal immune response to the WRSS1 was evaluated by assessing Fecal IgA (immunoglobulin A) antibody responses in stool to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in ELISA assays, at Days -1, 7, 28, 35, 56, 63, and 84. 4-fold increases of LPS and invaplex-specific IgA in stool beyond baseline mean + 3 SD (standard deviation) were determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer. Pro-inflammatory cytokines (IL-1β, IL-8, TNF-α and IFN-γ) were measured in stool extracts using commercially available ELISA kits.

The mucosal immune response to the WRSS1 was evaluated by assessing Fecal IgA (immunoglobulin A) antibody responses in stool to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in ELISA assays, at Days -1, 7, 28, 35, 56, 63, and 84. 4-fold increases of LPS and invaplex-specific IgA in stool beyond baseline mean + 3 SD (standard deviation) were determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer. Pro-inflammatory cytokines (IL-1β, IL-8, TNF-α and IFN-γ) were measured in stool extracts using commercially available ELISA kits.

The mucosal immune response to the WRSS1 was evaluated by assessing Fecal IgA (immunoglobulin A) antibody responses in stool to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in ELISA assays, at Days -1, 7, 28, 35, 56, 63, and 84. 4-fold increases of LPS and invaplex-specific IgA in stool beyond baseline mean + 3 SD (standard deviation) were determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer. Pro-inflammatory cytokines (IL-1β, IL-8, TNF-α and IFN-γ) were measured in stool extracts using commercially available ELISA kits.

The mucosal immune response to the WRSS1 was evaluated by assessing Fecal IgA (immunoglobulin A) antibody responses in stool to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in ELISA assays, at Days -1, 7, 28, 35, 56, 63, and 84. 4-fold increases of LPS and invaplex-specific IgA in stool beyond baseline mean + 3 SD (standard deviation) were determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer. Pro-inflammatory cytokines (IL-1β, IL-8, TNF-α and IFN-γ) were measured in stool extracts using commercially available ELISA kits.

The mucosal immune response to the WRSS1 was evaluated by assessing Fecal IgA (immunoglobulin A) antibody responses in stool to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in ELISA assays, at Days -1, 7, 28, 35, 56, 63, and 84. 4-fold increases of LPS and invaplex-specific IgA in stool beyond baseline mean + 3 SD (standard deviation) were determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer. Pro-inflammatory cytokines (IL-1β, IL-8, TNF-α and IFN-γ) were measured in stool extracts using commercially available ELISA kits.

Fecal antibody responses were defined as a four-fold rise for specific IgA (immunoglobulin A) or a four-fold rise for the ratio of specific over total IgA at any time point after immunization. Fecal antibody response to the WRSS1 was evaluated by assessing Fecal IgA antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in ELISA assays at Days -1, 7, 28, 35, 56, 63, and 84 . For those participants with a zero titer at baseline fold-rise was defined as the follow-up titer.

Fecal antibody responses were defined as a four-fold rise for specific IgA (immunoglobulin A) or a four-fold rise for the ratio of specific over total IgA at any time point after immunization. Fecal antibody response to the WRSS1 was evaluated by assessing Fecal IgA antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in ELISA assays at Days -1, 7, 28, 35, 56, 63, and 84 . For those participants with a zero titer at baseline fold-rise was defined as the follow-up titer.

Fecal antibody responses were defined as a four-fold rise for specific IgA (immunoglobulin A) or a four-fold rise for the ratio of specific over total IgA at any time point after immunization. Fecal antibody response to the WRSS1 was evaluated by assessing Fecal IgA antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in ELISA assays at Days -1, 7, 28, 35, 56, 63, and 84 . For those participants with a zero titer at baseline fold-rise was defined as the follow-up titer.

Fecal antibody responses were defined as a four-fold rise for specific IgA (immunoglobulin A) or a four-fold rise for the ratio of specific over total IgA at any time point after immunization. Fecal antibody response to the WRSS1 was evaluated by assessing Fecal IgA antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in ELISA assays at Days -1, 7, 28, 35, 56, 63, and 84 . For those participants with a zero titer at baseline fold-rise was defined as the follow-up titer.

Fecal antibody responses were defined as a four-fold rise for specific IgA (immunoglobulin A) or a four-fold rise for the ratio of specific over total IgA at any time point after immunization. Fecal antibody response to the WRSS1 was evaluated by assessing Fecal IgA antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in ELISA assays at Days -1, 7, 28, 35, 56, 63, and 84 . For those participants with a zero titer at baseline fold-rise was defined as the follow-up titer.

Fecal antibody responses were defined as a four-fold rise for specific IgA (immunoglobulin A) or a four-fold rise for the ratio of specific over total IgA at any time point after immunization. Fecal antibody response to the WRSS1 was evaluated by assessing Fecal IgA antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in ELISA assays at Days -1, 7, 28, 35, 56, 63, and 84 . For those participants with a zero titer at baseline fold-rise was defined as the follow-up titer.

Fecal antibody responses were defined as a four-fold rise for specific IgA (immunoglobulin A) or a four-fold rise for the ratio of specific over total IgA at any time point after immunization. Fecal antibody response to the WRSS1 was evaluated by assessing Fecal IgA antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in ELISA assays at Days -1, 7, 28, 35, 56, 63, and 84 . For those participants with a zero titer at baseline fold-rise was defined as the follow-up titer.

Prevalence and distribution of vaccine shedding was determined by quantitative culture and polymerase chain reaction (PCR). The latter measured the mean relative abundance of microbiota by 16S ribosomal ribonucleic acid (rRNA) gene sequence analysis of stool at baseline and post-vaccination days. PCR and stool results were reported as positive if a positive result was reported at any time during the testing period.

Three oral doses of ~3x10^6 cfu WRSS1

One or Three oral doses of Placebo

One oral dose of ~3x10^3 cfu WRSS1

Three oral doses of ~3x10^4 cfu WRSS1

Three oral doses of ~3x10^5 cfu WRSS1

Three oral doses of ~3x10^6 cfu WRSS1

One or three oral doses of Placebo

Total of all reporting groups

Race and Ethnicity were not collected from any participant.

Additional row added to stratify participants by 'adults' and 'children' and give totals for each.

Additional row added to stratify participants by 'adults' and 'children' and give totals for each

Based on subject count over all non-serious adverse events. An Adverse event was defined as any untoward medical occurrence in humans, whether or not considered drug related, that occurred during the conduct of a clinical trial. Any change in clinical status, ECGs, routine labs, x-rays, physical examinations, etc., that was considered clinically significant by the study investigator, was considered an AE. This definition also included an exacerbation or worsening of pre-existing conditions or events, inter-current illnesses, injuries, or vaccine or drug interaction, or worsening of abnormal clinical laboratory values. All AEs were assessed by the clinician using a protocol defined grading system.

All participants who had been exposed to at least one dose of study product were included in the primary analysis for safety.

Maximum severity per participant of any systemic or any gastrointestinal reactogenicity recorded within 7 days of any vaccination is reported. Solicited Systemic reactogenicity events assessed included fever, headache, malaise, generalized myalgia, arthralgia, chills, reactive arthritis and decreased appetite. Intestinal solicited reactogenicity events assessed included abdominal cramps, abdominal pain, nausea, vomiting, loose stool, diarrhea, dysentery, bloating, excess flatulence and constipation. Diarrhea and dysentery were assessed both during inpatient (first three day period post-vaccination) and outpatient ( post-vaccination days 4-7) periods post-vaccination 1. Vaccinations 2 and 3 did not have an inpatient admission period for any participants. Diarrhea severity was determined on the basis of stool number, grading and stool weight during the inpatient period and by stool number and grading only during the outpatient period.

All participants who had been exposed to at least one dose of study product were included in the primary analysis for safety.

Adverse event (AE) was defined as any untoward medical occurrence in humans, whether or not considered drug related, that occurs during the conduct of a clinical trial. A Serious Adverse Event (SAE) , including serious suspected adverse reaction or serious adverse reaction as determined by the Investigator or the sponsor, was any event that results in any of the following outcomes: Inpatient hospitalization or prolongation of existing hospitalization , life-threatening AE that in the opinion of the investigator or sponsor put the participant at immediate risk of death, persistent or significant incapacity or substantial disruption, congenital abnormality or birth defect, a medically important event that may have jeopardized the participant or may have required intervention to prevent one of the other outcomes listed or death. Causality of the AE/SAE to the study drug was assessed by the Investigator as reasonable possibility that the study product caused the reported event.

All participants who had been exposed to at least one dose of study product were included in the primary analysis for safety. Adult Cohort A1 and Child Cohort B1 only received a single dose of study vaccine.

The mucosal immune response to WRSS1 was evaluated by assessing specific immunoglobulin A (IgA) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and a novel composition comprising invasin proteins and LPS from gram-negative bacteria (Invaplex) using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgA responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgA responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgA responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer..

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgA responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific immunoglobulin G (IgG ) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgG responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgG responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgG (immunoglobulin G) antibody responses to S. sonnei 2a Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine Invaplex-specific IgG responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS-specific IgG responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgG responses from circulating lymphocytes. Proportion of participants with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific immunoglobulin M (IgM) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgM responses from circulating lymphocytes. Proportion of children with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgM (immunoglobulin M) antibody responses to S. sonnei 2a Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine Invaplex-specific IgM responses from circulating lymphocytes. Proportion of children with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgM (immunoglobulin M) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- specific IgM responses from circulating lymphocytes. Proportion of children with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgM (immunoglobulin M) antibody responses to S. sonnei 2a Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine Invaplex-specific IgM responses from circulating lymphocytes. Proportion of children with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgM (immunoglobulin M) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS-specific IgM responses from circulating lymphocytes. Proportion of children with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The mucosal immune response to WRSS1 was evaluated by assessing specific IgM (immunoglobulin M) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex using the 'antibodies in lymphocyte supernatant' (ALS) assay on culture supernatants of cultured peripheral blood mononuclear cells from different study days before and after vaccination to determine LPS- and Invaplex-specific IgM responses from circulating lymphocytes. Proportion of children with a >= 4-fold increase in antibody titer beyond baseline (mean + 3 standard deviation) was determined. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7 and Day 28.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7 and Day 28.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7 and Day 28.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7 and Day 28.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7 and Day 28.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7 and Day 28.

The systemic immune response to WRSS1 was evaluated by assessing the IgA (immunoglobulin A) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7 and Day 28.

The systemic immune response to WRSS1 was evaluated by assessing the IgG (immunoglobulin G) antibody responses to S. sonnei 2a LPS (lipopolysaccharide) and Invaplex in serum samples at Days -1, 7, 28, 35, 56, 63 and 84. Serotype-specific LPS from the Walter Reed Army Institute was used to coat the ELISA plates. A ≥4-fold rise in serum antibody titers was considered significant. Fold rise is the ratio of follow-up titer/baseline titer. For those with a zero titer at baseline, fold-rise was defined as the follow-up titer.

The overall number of participants analyzed (N) were those who received at least one study vaccination and for whom research blood was collected and analyzed. Adult Cohort A1 and Child Cohort B1 received a single dose of study vaccine and had research blood collected only on Day 7 and Day 28.