Blood was collected for HAI assay which was conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The geometric mean titer was calculated for each study arm from the available results at 21 days after the second dose of H7N9 (Day 43).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for Neutralizing assay which was conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The geometric mean titer was calculated for each study arm from the available results at 21 days after the second dose of H7N9 (Day 43).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for Neut antibody assays for which valid results were reported.

Laboratory parameters include alanine aminotransferase (ALT), bilirubin, creatinine, hemoglobin, platelets and white blood cells (WBC). Thresholds for adverse events were considered as ALT 44 IU/L or greater (female) or 61 IU/L or greater (male); bilirubin 1.30 mg/dL or greater; creatinine 1.1 mg/dL or greater (female) or 1.4 mg/dL or greater (male); hemoglobin 11.4 g/dL or lower (female) or 12.4 g/dL or lower (male); platelets 139 x10^3/µL or below or 416 x10^3/µL or greater; or WBC or 3.9 x10^3/µL or lower or 10.6 x10^3/µL or higher.

The Safety Analysis population includes all participants who received at least one dose of study vaccine. Participants with at least one lab result reported for Day 8 were included for this outcome measure.

Laboratory parameters include alanine aminotransferase (ALT), bilirubin, creatinine, hemoglobin, platelets and white blood cells (WBC). Thresholds for adverse events were considered as ALT 44 IU/L or greater (female) or 61 IU/L or greater (male); bilirubin 1.30 mg/dL or greater; creatinine 1.1 mg/dL or greater (female) or 1.4 mg/dL or greater (male); hemoglobin 11.4 g/dL or lower (female) or 12.4 g/dL or lower (male); platelets 139 x10^3/µL or below or 416 x10^3/µL or greater; or WBC or 3.9 x10^3/µL or lower or 10.6 x10^3/µL or higher.

The Safety Analysis population includes all participants who received at least one dose of study vaccine. Participants with at least one lab result reported for Day 29 were included for this outcome measure.

Injection site AEs solicited on a memory aid provided to participants included Pain, Tenderness, Itching/Pruritus, Ecchymosis/Bruising (functional grade based on interference with daily activities), Ecchymosis/Bruising (any measured value >0mm), Erythema/Redness (functional grade), Erythema/ Redness (any measured value >0mm), Induration/Swelling (functional grade), and Induration/Swelling (any measured value >0mm). Participants are considered reporting the injection site AE if they reported mild or greater severity at any time during the 8 days at or following the first vaccination.

The Safety Analysis population includes all participants who received at least one dose of study vaccine. Participants who received the first dose of study vaccine were included for this outcome measure.

Injection site AEs solicited on a memory aid provided to participants included Pain, Tenderness, Itching/Pruritus, Ecchymosis/Bruising (functional grade based on interference with daily activities), Ecchymosis/Bruising (any measured value >0mm), Erythema/Redness (functional grade), Erythema/ Redness (any measured value >0mm), Induration/Swelling (functional grade), and Induration/Swelling (any measured value >0mm). Participants are considered reporting the injection site AE if they reported mild or greater severity at any time during the 8 days at or following the second vaccination.

The Safety Analysis population includes all participants who received at least one dose of study vaccine. Participants who received the second dose of study vaccine were included for this outcome measure.

SAEs included any untoward medical occurrence that resulted in death; was life threatening; was a persistent/significant disability/incapacity; required inpatient hospitalization or prolongation or a congenital anomaly/birth defect. Events are included if deemed by the investigator to be related to the study product.

The Safety Analysis population includes all participants who received at least one dose of study vaccine.

Systemic AEs solicited on a memory aid provided to participants included Elevated Oral Temperature, Feverishness, Fatigue, Malaise, Myalgia, Arthralgia, Headache, and Nausea. Participants are considered reporting the systemic AE if they reported mild or greater severity at any time during the 8 days at or following the first vaccination.

The Safety Analysis population includes all participants who received at least one dose of study vaccine. Participants who received the first dose of study vaccine were included for this outcome measure.

Systemic AEs solicited on a memory aid provided to participants included Elevated Oral Temperature, Feverishness, Fatigue, Malaise, Myalgia, Arthralgia, Headache, and Nausea. Participants are considered reporting the systemic AE if they reported mild or greater severity at any time during the 8 days at or following the second vaccination.

The Safety Analysis population includes all participants who received at least one dose of study vaccine. Participants who received the second dose of study vaccine were included for this outcome measure.

Blood was collected for the HAI assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The percentage of participants with HAI titer >= 1:40 was calculated for each study group from the available results at 21 days after second dose of H7N9 (Day 43).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for the Neutralizing assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The percentage of participants with Neut titer >= 1:40 was calculated for each study group from the available results at 21 days after second dose of H7N9 (Day 43).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for Neut antibody assays for which valid results were reported.

Blood was collected for the HAI assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. Seroconversion was defined as HAI pre-vaccination titer <1:10 and post-vaccination titer >= 1:40 or pre-vaccination titer >= 1:10 and minimum 4-fold rise in post-vaccination antibody titer. 21 days after second dose of H7N9 is Day 43.

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for the Neutralizing assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. Seroconversion was defined as Neut pre-vaccination titer <1:10 and post-vaccination titer >= 1:40 or pre-vaccination titer >= 1:10 and minimum 4-fold rise in post-vaccination antibody titer. 21 days after second dose of H7N9 is Day 43.

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for Neut antibody assays for which valid results were reported.

Blood was collected for HAI assay which was conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The geometric mean titer was calculated for each study arm from the available results at baseline (Day 1).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for HAI assay which was conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The geometric mean titer was calculated for each study arm from the available results at 7 days post first vaccination (Day 8).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for HAI assay which was conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The geometric mean titer was calculated for each study arm from the available results at 21 days post first vaccination (Day 22).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for HAI assay which was conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The geometric mean titer was calculated for each study arm from the available results at 7 days post second vaccination (Day 29).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for Neutralizing assay which was conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The geometric mean titer was calculated for each study arm from the available results at baseline (Day 1).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for Neut antibody assays for which valid results were reported.

Blood was collected for Neutralizing assay which was conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The geometric mean titer was calculated for each study arm from the available results at 7 days post first vaccination (Day 8).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for Neut antibody assays for which valid results were reported.

Blood was collected for Neutralizing assay which was conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The geometric mean titer was calculated for each study arm from the available results at 21 days post first vaccination (Day 22).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for Neut antibody assays for which valid results were reported.

Blood was collected for Neutralizing assay which was conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The geometric mean titer was calculated for each study arm from the available results at 7 days post second vaccination (Day 29).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for Neut antibody assays for which valid results were reported.

SAEs included any untoward medical occurrence that resulted in death; was life threatening; was a persistent/significant disability/incapacity; required inpatient hospitalization or prolongation or a congenital anomaly/birth defect. All events are included regardless of relationship to the study product.

The Safety Analysis population includes all participants who received at least one dose of study vaccine.

Adverse events were defined as any untoward medical occurrence in a participant administered a pharmaceutical product regardless of its causal relationship to the study treatment. Non-serious AEs were collected from participants at follow up visits through 21 days after each vaccination. Adverse events were MedDRA coded and are summarized by MedDRA System Organ Class (SOC).

The Safety Analysis population includes all participants who received at least one dose of study vaccine. Participants who received Vaccination 1 were included for this outcome measure.

Adverse events were defined as any untoward medical occurrence in a participant administered a pharmaceutical product regardless of its causal relationship to the study treatment. Non-serious AEs were collected from participants at follow up visits through 21 days after each vaccination. Adverse events were MedDRA coded and are summarized by MedDRA System Organ Class (SOC).

The Safety Analysis population includes all participants who received at least one dose of study vaccine. Participants who received Vaccination 2 were included for this outcome measure.

Participants were queried at each visit for the occurrence of medically-attended adverse events (MAAEs), including new-onset chronic medical conditions (NOCMCs) and potentially immune-mediated medical conditions (PIMMCs) throughout the duration of the study.

The Safety Analysis population includes all participants who received at least one dose of study vaccine.

Adverse events were defined as any untoward medical occurrence in a participant administered a pharmaceutical product regardless of its causal relationship to the study treatment. Non-serious AEs were collected from participants at follow up visits through 21 days after each vaccination. The site investigator determined vaccine related as "a reasonable possibility that the study product caused the AE. Reasonable possibility means that there is evidence to suggest a causal relationship between the study product and the AE." Adverse events were MedDRA coded and are summarized by MedDRA System Organ Class (SOC).

The Safety Analysis population includes all participants who received at least one dose of study vaccine. Participants who received Vaccination 1 were included for this outcome measure.

Adverse events were defined as any untoward medical occurrence in a participant administered a pharmaceutical product regardless of its causal relationship to the study treatment. Non-serious AEs were collected from participants at follow up visits through 21 days after each vaccination. The site investigator determined vaccine related as "a reasonable possibility that the study product caused the AE. Reasonable possibility means that there is evidence to suggest a causal relationship between the study product and the AE." Adverse events were MedDRA coded and are summarized by MedDRA System Organ Class (SOC).

The Safety Analysis population includes all participants who received at least one dose of study vaccine. Participants who received Vaccination 2 were included for this outcome measure.

Blood was collected for the HAI assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The percentage of participants with HAI titer >= 1:40 was calculated for each study group from the available results at baseline (Day 1).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for the HAI assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The percentage of participants with HAI titer >= 1:40 was calculated for each study group from the available results at 7 days post first vaccination (Day 8).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for the HAI assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The percentage of participants with HAI titer >= 1:40 was calculated for each study group from the available results at 21 days post first vaccination (Day 22).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for the HAI assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The percentage of participants with HAI titer >= 1:40 was calculated for each study group from the available results at 7 days post second vaccination (Day 29).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for the Neutralizing assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The percentage of subjects with Neut titer >= 1:40 was calculated for each study group from the available results at baseline (Day 1).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for Neut antibody assays for which valid results were reported.

Blood was collected for the Neutralizing assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The percentage of subjects with Neut titer >= 1:40 was calculated for each study group from the available results at 7 days post first vaccination (Day 8).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for Neut antibody assays for which valid results were reported.

Blood was collected for the Neutralizing assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The percentage of participants with Neut titer >= 1:40 was calculated for each study group from the available results at 21 days post first vaccination (Day 22).

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for Neut antibody assays for which valid results were reported.

Blood was collected for the Neutralizing assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The percentage of participants with Neut titer >= 1:40 was calculated for each study group from the available results at 7 days post second vaccination (Day 29).

Blood was collected for the Neutralizing assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. The percentage of participants with Neut titer >= 1:40 was calculated for each study group from the available results at 7 days post second vaccination (Day 29).

Blood was collected for the HAI assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. Seroconversion was defined as HAI pre-vaccination titer <1:10 and post-vaccination titer >= 1:40 or pre-vaccination titer >= 1:10 and minimum 4-fold rise in post-vaccination antibody titer. Day 8 is 7 days after the first dose of H7N9.

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for the HAI assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. Seroconversion was defined as HAI pre-vaccination titer <1:10 and post-vaccination titer >= 1:40 or pre-vaccination titer >= 1:10 and minimum 4-fold rise in post-vaccination antibody titer. Day 22 is 21 days after the first dose of H7N9.

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for the HAI assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. Seroconversion was defined as HAI pre-vaccination titer <1:10 and post-vaccination titer >= 1:40 or pre-vaccination titer >= 1:10 and mininmum 4-fold rise in post-vaccination antibody titer. Day 29 is 7 days after the second dose of H7N9.

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for HAI antibody assays for which valid results were reported.

Blood was collected for the Neutralizing assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. Seroconversion was defined as Neut pre-vaccination titer <1:10 and post-vaccination titer >= 1:40 or pre-vaccination titer >= 1:10 and minimum 4-fold rise in post-vaccination antibody titer. Day 8 is 7 days after the first dose of H7N9.

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for Neut antibody assays for which valid results were reported.

Blood was collected for the Neutralizing assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. Seroconversion was defined as Neut pre-vaccination titer <1:10 and post-vaccination titer >= 1:40 or pre-vaccination titer >= 1:10 and minimum 4-fold rise in post-vaccination antibody titer. Day 22 is 21 days after the first dose of H7N9.

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for Neut antibody assays for which valid results were reported.

Blood was collected for the Neutralizing assay conducted with the 2017 H7N9 vaccine virus as the antigen. Each sample was tested at least twice per the laboratory's standard operating procedure, and the geometric mean of the replicate results was calculated as that sample's result. Seroconversion was defined as Neut pre-vaccination titer <1:10 and post-vaccination titer >= 1:40 or pre-vaccination titer >= 1:10 and minimum 4-fold rise in post-vaccination antibody titer. Day 29 is 7 days after the second dose of H7N9.

The modified intent-to-treat (mITT) population includes all participants who received at least one study vaccination and contributed both pre- and at least one post-study vaccination venous blood samples for Neut antibody assays for which valid results were reported.