Number of adult participants with solicited local AEs for 7 days post first vaccination was reported. An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study. Solicited AEs were used to assess the reactogenicity of the study vaccine and were pre-defined as local (at the injection site) AEs for which participants were specifically asked and which were noted by participants in their reactogenicity diary for 7 days post first vaccination (day of first vaccination and the subsequent 7 days). Solicited local AEs are injection site pain/tenderness, erythema, swelling at the vaccination site.

Full Analysis Set - Adults (FAS-A) included all enrolled adult participants with at least one vaccine administration documented.

Number of adult participants with solicited systemic AEs for 7 days post first vaccination was reported. An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study. Solicited AEs were used to assess the reactogenicity of the study vaccine and were predefined as systemic AEs for which participants were specifically asked and which were noted by participants in their reactogenicity diary for 7 days post first vaccination. Participants were instructed on how to note signs and symptoms in the diary on a daily basis for 7 days post first vaccination (day of first vaccination and the subsequent 7 days) for the following solicited systemic AEs: fatigue, headache, nausea, myalgia.

FAS-A included all enrolled adult participants with at least one vaccine administration documented.

Number of adult participants with unsolicited AEs for 28 days post first vaccination was reported. An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study. Unsolicited AEs were defined as AEs for which the participants were not specifically questioned in the participant's reactogenicity diary.

FAS-A included all enrolled adult participants with at least one vaccine administration documented.

Number of adult participants with SAEs from first vaccination until EOS were reported. An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study. SAEs were defined as any untoward medical occurrence that at any dose results in any of the following outcomes: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly/birth defect; suspected transmission of any infectious agent via a medicinal product or medically important.

FAS-A included all enrolled adult participants with at least one vaccine administration documented.

Number of adult participants with AESIs from first vaccination until EOS were reported. Thrombosis with thrombocytopenia syndrome (TTS) in adults was considered an AESI in this study. TTS is a syndrome characterized by a combination of both a thrombotic event and thrombocytopenia.

FAS-A included all enrolled adult participants with at least one vaccine administration documented.

Number of adult participants with MAAEs until 6 months post first vaccination was reported. MAAEs were defined as AEs with medically attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Routine study visits were not considered medically attended visits. New onset of chronic diseases was collected as part of the MAAEs.

FAS-A included all enrolled adult participants with at least one vaccine administration documented.

Number of adult participants with AEs leading to study discontinuation were reported. An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study. All AEs leading to discontinuation from the study (regardless of the causal relationship) were reported for all adult participants from the moment of first vaccination until completion of the participant's last study-related procedure.

FAS-A included all enrolled adult participants with at least one vaccine administration documented.

Serological response to vaccination as measured by S-ELISA in adult participants 28 days post first vaccination was reported.

Per-protocol Immunogenicity-Adults (PPI-A) set included all vaccinated adult participants for whom immunogenicity data were available excluding adult participants with major protocol deviations that were expected to impact the immunogenicity outcomes. Here, "N" (Number of participants analyzed) signifies the number of participants that were evaluable for this outcome measure.

Number of adult participants with solicited local AEs for 7 days post booster vaccination was reported. An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study. Solicited AEs were used to assess the reactogenicity of the study vaccine and were pre-defined as local (at the injection site) AEs for which participants were specifically asked and which were noted by participants in their reactogenicity diary for 7 days post booster vaccination (day of booster vaccination and the subsequent 7 days). Solicited local AEs are: injection site pain/tenderness, erythema, swelling at the vaccination site.

FAS-A included all enrolled adult participants with at least one vaccine administration documented. Data for this outcome measure was planned to be collected and analyzed only for the participants in arm "Group 4 (Adults): Vaccine-naive: Ad26.COV2.S 5*10^10 vp", as only this arm received the booster vaccination.

Number of adult participants with solicited systemic AEs for 7 days post booster vaccination was reported. An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study. Solicited AEs were used to assess the reactogenicity of the study vaccine and were predefined as systemic AEs for which participants were specifically asked and which were noted by participants in their reactogenicity diary for 7 days post booster vaccination. Participants were instructed on how to note signs and symptoms in the diary on a daily basis for 7 days post-vaccination (day of booster vaccination and the subsequent 7 days) for the following solicited systemic AEs: fatigue, headache, nausea, myalgia.

FAS-A included all enrolled adult participants with at least one vaccine administration documented. Data for this outcome measure was planned to be collected and analyzed only for the participants in arm "Group 4 (Adults): Vaccine-naive: Ad26.COV2.S 5*10^10 vp", as only this arm received the booster vaccination.

Number of adult participants with unsolicited AEs for 28 days post booster vaccination was reported. An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study. Unsolicited AEs were defined as AEs for which the participants were not specifically questioned in the participant's reactogenicity diary.

FAS-A included all enrolled adult participants with at least one vaccine administration documented. Data for this outcome measure was planned to be collected and analyzed only for the participants in arm "Group 4 (Adults): Vaccine-naive: Ad26.COV2.S 5*10^10 vp", as only this arm received the booster vaccination.

Number of adult participants with SAEs post booster vaccination until EOS were reported. AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study. SAE were defined as any untoward medical occurrence that at any dose results in any of the following outcomes: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly/birth defect; suspected transmission of any infectious agent via a medicinal product or medically important.

FAS-A included all enrolled adult participants with at least one vaccine administration documented. Data for this outcome measure was planned to be collected and analyzed only for the participants in arm "Group 4 (Adults): Vaccine-naive: Ad26.COV2.S 5*10^10 vp", as only this arm received the booster vaccination.

Number of adult participants with AESI post booster vaccination until EOS were reported. Thrombosis with thrombocytopenia syndrome (TTS) in adults was considered an AESI in this study. TTS is a syndrome characterized by a combination of both a thrombotic event and thrombocytopenia.

FAS-A included all enrolled adult participants with at least one vaccine administration documented. Data for this outcome measure was planned to be collected and analyzed only for the participants in arm "Group 4 (Adults): Vaccine-naive: Ad26.COV2.S 5*10^10 vp", as only this arm received the booster vaccination.

Number of adult participants with MAAEs until 6 months post booster vaccination were reported. MAAEs were defined as AEs with medically attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Routine study visits were not considered medically attended visits. New onset of chronic diseases was collected as part of the MAAEs.

FAS-A included all enrolled adult participants with at least one vaccine administration documented. Data for this outcome measure was planned to be collected and analyzed only for the participants in arm "Group 4 (Adults): Vaccine-naive: Ad26.COV2.S 5*10^10 vp", as only this arm received the booster vaccination.

Number of adult participants with AEs leading to study discontinuation post booster vaccination until EOS were reported. An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/biological agent under study. All AEs leading to discontinuation from the study (regardless of the causal relationship) were reported for all adult participants from the moment of booster vaccination until completion of the participant's last study-related procedure.

FAS-A included all enrolled adult participants with at least one vaccine administration documented. Data for this outcome measure was planned to be collected and analyzed only for the participants in arm "Group 4 (Adults): Vaccine-naive: Ad26.COV2.S 5*10^10 vp", as only this arm received the booster vaccination.

Number of adult participants with pregnancy outcomes were reported. Pregnancy outcomes in adult participants included live term birth, live preterm birth, stillbirth, and abortion.

FAS-A included all enrolled adult participants with at least one vaccine administration documented. Here "N" (Number of participants analyzed) signifies the number of participants that were evaluable for this outcome measure.

Number of adult participants with pregnancy related AEs throughout pregnancy were reported. Pregnancy related AEs in adult participants were collected based on 2 baseline gestational age groups (adult participants who received vaccination at 16 to 27 weeks [>=16 weeks to <28 weeks] and at 28 to 38 weeks [>=28 weeks to <=38 weeks]) and included gestational hypertension, foetal growth restriction, haemorrhage in pregnancy, polyhydramnios, pre-eclampsia, premature rupture of membranes, preterm premature rupture of membranes, bradycardia foetal, premature baby, amniorrhexis, foetalgrowth restriction, amniotic fluid volume decreased.

FAS-A included all enrolled adult participants with at least one vaccine administration documented. Here "n"(number analyzed) signifies number of participants analyzed for specified categories.

Serological response to first vaccination as measured by S-ELISA at all blood collection timepoints post first vaccination were reported.

PPI-A set included all vaccinated adult participants for whom immunogenicity data were available excluding adult participants with major protocol deviations that were expected to impact the immunogenicity outcomes. Here "N" (Number of participants analyzed) signifies the number of participants that were evaluable for this outcome measure and "n" (number analyzed) signifies number of participants analyzed at specified timepoints.

Serological response to first vaccination measured by VNA titers at 28 days in adult participants post first vaccination was reported. Data were expressed as 50 percent (%) inhibitory concentration (IC50) units.

PPI-A set included all vaccinated adult participants for whom immunogenicity data were available excluding adult participants with major protocol deviations that were expected to impact the immunogenicity outcomes. Here "N" (Number of participants analyzed) signifies the number of participants that were evaluable for this outcome measure.

Serological response to vaccination as measured by binding (S-ELISA) antibody titers in adult participants at blood collection time points post booster vaccination were reported.

PPI-A set included all vaccinated adult participants with available immunogenicity data excluding participants with major protocol deviations that impact immunogenicity outcomes. Data for this outcome measure was planned to be collected and analyzed only for the participants in arm "Group 4 (Adults): Vaccine-naive: Ad26.COV2.S 5*10^10 vp", as only this arm received the booster vaccination.

Serological response to booster vaccination measured by neutralizing VNA antibody titers in adult participants at blood collection time points post booster vaccination were reported. Data were expressed as IC50 units.

PPI-A set included all vaccinated adult participants with available immunogenicity data excluding participants with major protocol deviations that impact immunogenicity outcomes. Data for this outcome measure was planned to be collected and analyzed only for the participants in arm "Group 4 (Adults): Vaccine-naive: Ad26.COV2.S 5*10^10 vp", as only this arm received the booster vaccination.

Serological response to vaccination as measured by S-ELISA at birth (that is, in cord blood) and at 2 months and 6 months of age in neonates and infants born to adult participants were reported.

Per-protocol immunogenicity- non-vaccinated neonates/infants (PPI-NVN) included all non-vaccinated neonates/infants born to Ad26.COV2.S vaccinated adult participants for whom immunogenicity data were available. Here "N" (Number of participants analyzed) signifies the number of participants that were evaluable for this outcome measure and "n"(number analyzed) signifies number of participants analyzed at specified timepoints.

Serological response to vaccination as measured by VNA titers at birth (that is, in cord blood) in neonates and infants born to adult participants were reported. Data were expressed as IC50 units.

Per-protocol immunogenicity- non-vaccinated neonates/infants (PPI-NVN) included all non-vaccinated neonates/infants born to Ad26.COV2.S vaccinated adult participants for whom immunogenicity data were available. Here "N" (Number of participants analyzed) signifies the number of participants that were evaluable for this outcome measure.

An AE is any untoward medical occurrence in participants in the study that does not necessarily have a causal relationship with pharmaceutical/biological agent under study. SAE: any untoward medical occurrence that resulted in following outcomes: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly/birth defect; suspected transmission of any infectious agent via a medicinal product or medically important. MIS-C: a serious and potentially fatal condition in infants and children with SARS-CoV-2, which resulted in inflammation involving multiple organs. Symptoms of MIS-C: persistent fever, fatigue and signs and symptoms including multiorgan systems (cardiac, gastrointestinal, renal, hematologic, dermatologic, neurologic) involvement, elevated inflammatory markers and, in severe cases, hypotension and shock.

Full Analysis Set - Non-vaccinated Neonates/Infants (FAS-NVN) included all non-vaccinated neonates/infants born to Ad26.COV2.S vaccinated adult participants.

Number of neonates and infants with AESIs from birth until 12 months of age in neonates and infants born to adult participants were reported. TTS is a syndrome characterized by a combination of both a thrombotic event and thrombocytopenia.

FAS-NVN included all non-vaccinated neonates/infants (NVN) born to Ad26.COV2.S vaccinated adult participants.

Number of neonates and infants with MAAEs from birth until 6 months of age in neonates and infants born to adult participants were reported. MAAEs were defined as AEs with medically attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Routine study visits were not considered medically attended visits. New onset of chronic diseases were collected as part of the MAAEs.

FAS-NVN included all non-vaccinated neonates/infants (NVN) born to Ad26.COV2.S vaccinated adult participants.

Number of neonates and infants with AEs leading to study discontinuation from birth until study discontinuation were reported. An AE is any untoward medical occurrence in participants who does not necessarily have a causal relationship with pharmaceutical/biological agent under study. All AEs leading to discontinuation from the study (regardless of the causal relationship) were reported for all neonates and infants.

FAS-NVN included all non-vaccinated neonates/infants (NVN) born to Ad26.COV2.S vaccinated adult participants.

Number of neonates and infants with different birth outcomes from birth until 12 months of age were reported. Neonate/infant outcomes included normal neonate, term neonate with (or without) complications, preterm neonate with (or without) complications, neonatal infection, respiratory distress, congenital anomalies, neonatal death, low birth weight, and small for gestational age.

FAS-NVN included all non-vaccinated neonates/infants (NVN) born to Ad26.COV2.S vaccinated adult participants. Here 'N' (Number of participants analyzed) signifies the number of participants who completed the neonatal medical history form and were analyzed for this outcome measure.