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Safety, Immunogenicity, and Efficacy of the BNT162b2 Covid-19 Vaccine in Adolescents. BACKGROUND: Until very recently, vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had not been authorized for emergency use in persons younger than 16 years of age. Safe, effective vaccines are needed to protect this population, facilitate in-person learning and socialization, and contribute to herd immunity. METHODS: In this ongoing multinational, placebo-controlled, observer-blinded trial, we randomly assigned participants in a 1:1 ratio to receive two injections, 21 days apart, of 30 μg of BNT162b2 or placebo. Noninferiority of the immune response to BNT162b2 in 12-to-15-year-old participants as compared with that in 16-to-25-year-old participants was an immunogenicity objective. Safety (reactogenicity and adverse events) and efficacy against confirmed coronavirus disease 2019 (Covid-19; onset, ≥7 days after dose 2) in the 12-to-15-year-old cohort were assessed. RESULTS: Overall, 2260 adolescents 12 to 15 years of age received injections; 1131 received BNT162b2, and 1129 received placebo. As has been found in other age groups, BNT162b2 had a favorable safety and side-effect profile, with mainly transient mild-to-moderate reactogenicity (predominantly injection-site pain [in 79 to 86% of participants], fatigue [in 60 to 66%], and headache [in 55 to 65%]); there were no vaccine-related serious adverse events and few overall severe adverse events. The geometric mean ratio of SARS-CoV-2 50% neutralizing titers after dose 2 in 12-to-15-year-old participants relative to 16-to-25-year-old participants was 1.76 (95% confidence interval [CI], 1.47 to 2.10), which met the noninferiority criterion of a lower boundary of the two-sided 95% confidence interval greater than 0.67 and indicated a greater response in the 12-to-15-year-old cohort. Among participants without evidence of previous SARS-CoV-2 infection, no Covid-19 cases with an onset of 7 or more days after dose 2 were noted among BNT162b2 recipients, and 16 cases occurred among placebo recipients. The observed vaccine efficacy was 100% (95% CI, 75.3 to 100). CONCLUSIONS: The BNT162b2 vaccine in 12-to-15-year-old recipients had a favorable safety profile, produced a greater immune response than in young adults, and was highly effective against Covid-19. (Funded by BioNTech and Pfizer; C4591001 ClinicalTrials.gov number, NCT04368728.).

We conducted a randomized, placebo-controlled, observer-blinded, phase 3 trial as part of a phase 1–2–3 trial assessing BNT162b2 safety, immunogenicity, and efficacy in healthy persons 12 years of age or older. This report presents findings from 12-to-15-year-old participants enrolled in the United States, including descriptive comparisons of safety between participants in that age cohort and those who were 16 to 25 years of age and an evaluation of the noninferiority of immunogenicity in the 12-to-15-year-old cohort to that in the 16-to-25-year-old cohort. Data were collected through the cutoff date of March 13, 2021. Eligible participants were healthy or had stable preexisting disease (including hepatitis B, hepatitis C, or human immunodeficiency virus infection). Persons with a previous clinical or virologic Covid-19 diagnosis or SARS-CoV-2 infection, previous coronavirus vaccination, diagnosis of an immunocompromising or immunodeficiency disorder, or treatment with immunosuppressive therapy (including cytotoxic agents and systemic glucocorticoids) were excluded.

us infection). Persons with a previous clinical or virologic Covid-19 diagnosis or SARS-CoV-2 infection, previous coronavirus vaccination, diagnosis of an immunocompromising or immunodeficiency disorder, or treatment with immunosuppressive therapy (including cytotoxic agents and systemic glucocorticoids) were excluded. The ethical conduct of the trial is summarized in the Supplementary Appendix, available with the full text of this article at NEJM.org. Additional details of the trial are provided in the protocol, available at NEJM.org. Pfizer was responsible for the trial design and conduct, data collection, data analysis, data interpretation, and writing of the manuscript that was submitted. Both Pfizer and BioNTech manufactured the vaccine and placebo. BioNTech was the regulatory sponsor of the trial and contributed to data interpretation and writing of the manuscript. All data were available to the authors, who vouch for their accuracy and completeness and for the adherence of the trial to the protocol. Randomization was conducted with the use of an interactive Web-based response system. Participants were assigned in a 1:1 ratio to receive two intramuscular injections of 30 μg of BNT162b2 or placebo (saline) 21 days apart. For evaluation of immediate vaccine-associated reactions, participants were observed in the clinic for 30 minutes after vaccination.

use of an interactive Web-based response system. Participants were assigned in a 1:1 ratio to receive two intramuscular injections of 30 μg of BNT162b2 or placebo (saline) 21 days apart. For evaluation of immediate vaccine-associated reactions, participants were observed in the clinic for 30 minutes after vaccination. Safety objectives included the assessment of local or systemic reactogenicity events, which were recorded by the participants in an electronic diary (e-diary) for 7 days after each dose. Unsolicited adverse events (i.e., those reported by the participant without e-diary prompting) and serious adverse events were also recorded from receipt of the first dose through 1 month and 6 months after dose 2, respectively.

e recorded by the participants in an electronic diary (e-diary) for 7 days after each dose. Unsolicited adverse events (i.e., those reported by the participant without e-diary prompting) and serious adverse events were also recorded from receipt of the first dose through 1 month and 6 months after dose 2, respectively. Immunogenicity assessments (SARS-CoV-2 serum neutralization assay and receptor-binding domain [RBD]–binding or S1-binding IgG direct Luminex immunoassays) were performed before vaccination and 1 month after dose 2, as described previously.3 The immunogenicity objective was to show noninferiority of the immune response to BNT162b2 in 12-to-15-year-old participants as compared with that in 16-to-25-year-old participants. Noninferiority was assessed among participants who had no evidence of previous SARS-CoV-2 infection with the use of the two-sided 95% confidence interval for the geometric mean ratio of SARS-CoV-2 50% neutralizing titers in 12-to-15-year-old participants as compared with 16-to-25-year-old participants 1 month after dose 2. BNT162b2 immunogenicity was evaluated in participants with and those without serologic or virologic evidence of previous SARS-CoV-2 infection. Corresponding end points were the geometric mean SARS-CoV-2 neutralizing titers at baseline (i.e., immediately before receipt of the first injection) and 1 month after dose 2 and geometric mean fold rises (GMFRs) in titers from baseline to 1 month after dose 2.

ic or virologic evidence of previous SARS-CoV-2 infection. Corresponding end points were the geometric mean SARS-CoV-2 neutralizing titers at baseline (i.e., immediately before receipt of the first injection) and 1 month after dose 2 and geometric mean fold rises (GMFRs) in titers from baseline to 1 month after dose 2. The efficacy of BNT162b2 against confirmed Covid-19 with an onset 7 or more days after dose 2 was summarized in participants who did not have evidence of previous SARS-CoV-2 infection, as well as in all vaccinated participants. Surveillance for potential Covid-19 cases was undertaken throughout the trial; if acute respiratory illness developed in a participant, the participant was tested for SARS-CoV-2. Methods for identifying SARS-CoV-2 infections and Covid-19 diagnoses are summarized in the Supplementary Appendix. The safety population included all participants who received at least one dose of BNT162b2 or placebo. The reactogenicity subset included all 12-to-15-year-old participants and a subset of 16-to-25-year-old participants (those who received an e-diary to record reactogenicity events). Safety end points are presented descriptively as counts, percentages, and associated Clopper–Pearson two-sided 95% confidence intervals, with adverse events and serious adverse events described according to terms in the Medical Dictionary for Regulatory Activities, version 23.1, for each group.

reactogenicity events). Safety end points are presented descriptively as counts, percentages, and associated Clopper–Pearson two-sided 95% confidence intervals, with adverse events and serious adverse events described according to terms in the Medical Dictionary for Regulatory Activities, version 23.1, for each group. Immunogenicity was assessed in a random subset of participants in each age cohort with the use of a simple random-sample selection procedure. For immunogenicity assessments, all participants in both age cohorts were from U.S. sites. The dose 2 immunogenicity population that could be evaluated included participants who underwent randomization and received two BNT162b2 doses in accordance with the protocol, received dose 2 within the prespecified window (19 to 42 days after dose 1), had at least one valid and determinate immunogenicity result from a blood sample obtained within 28 to 42 days after dose 2, and had no major protocol deviations. Noninferiority of the immune response to BNT162b2 in 12-to-15-year-old participants as compared with that in 16-to-25-year-old participants was assessed on the basis of the geometric mean ratio of SARS-CoV-2 50% neutralizing titers. A sample of 225 BNT162b2 recipients who could be evaluated (or 280 BNT162b2 recipients overall) in each age cohort was estimated to provide 90.8% power for declaring noninferiority (defined as a lower limit of the 95% confidence interval for the geometric mean ratio of >0.67). A testing laboratory supply limitation of the qualified viral lot used for assay validation and clinical testing resulted in the trial having fewer participants than anticipated for the immunogenicity analyses. Calculations of the geometric mean ratios, geometric mean titers, and GMFRs are described in the Supplementary Appendix.

aboratory supply limitation of the qualified viral lot used for assay validation and clinical testing resulted in the trial having fewer participants than anticipated for the immunogenicity analyses. Calculations of the geometric mean ratios, geometric mean titers, and GMFRs are described in the Supplementary Appendix. Although the formal evaluation of efficacy was to be based on the overall results obtained across all age cohorts, the statistical analysis plan specified that descriptive efficacy summaries would be provided for each age cohort (the stratification factor). The efficacy analysis for the 12-to-15-year-old cohort was planned as a descriptive analysis because the number of cases that would occur in the age subgroups was unknown. The efficacy population that could be evaluated included all eligible 12-to-15-year-old participants who underwent randomization and received two doses of BNT162b2 or placebo, received dose 2 within the prespecified window (19 to 42 days after dose 1), and had no major protocol deviations. The all-available efficacy population included all participants who received one or two doses. Vaccine efficacy was defined as 100×(1−IRR), where IRR is the ratio of the rate of a first confirmed Covid-19 illness in the BNT162b2 group to the corresponding rate in the placebo group. Two-sided Clopper–Pearson 95% confidence intervals were calculated (not adjusted for multiple comparisons). Because the number of participants who reported symptoms but were missing a valid polymerase-chain-reaction test result was small, data for these participants were not imputed in the analysis.

us infection). Persons with a previous clinical or virologic Covid-19 diagnosis or SARS-CoV-2 infection, previous coronavirus vaccination, diagnosis of an immunocompromising or immunodeficiency disorder, or treatment with immunosuppressive therapy (including cytotoxic agents and systemic glucocorticoids) were excluded. The ethical conduct of the trial is summarized in the Supplementary Appendix, available with the full text of this article at NEJM.org. Additional details of the trial are provided in the protocol, available at NEJM.org. Pfizer was responsible for the trial design and conduct, data collection, data analysis, data interpretation, and writing of the manuscript that was submitted. Both Pfizer and BioNTech manufactured the vaccine and placebo. BioNTech was the regulatory sponsor of the trial and contributed to data interpretation and writing of the manuscript. All data were available to the authors, who vouch for their accuracy and completeness and for the adherence of the trial to the protocol.

Randomization was conducted with the use of an interactive Web-based response system. Participants were assigned in a 1:1 ratio to receive two intramuscular injections of 30 μg of BNT162b2 or placebo (saline) 21 days apart. For evaluation of immediate vaccine-associated reactions, participants were observed in the clinic for 30 minutes after vaccination.

Safety objectives included the assessment of local or systemic reactogenicity events, which were recorded by the participants in an electronic diary (e-diary) for 7 days after each dose. Unsolicited adverse events (i.e., those reported by the participant without e-diary prompting) and serious adverse events were also recorded from receipt of the first dose through 1 month and 6 months after dose 2, respectively.

Immunogenicity assessments (SARS-CoV-2 serum neutralization assay and receptor-binding domain [RBD]–binding or S1-binding IgG direct Luminex immunoassays) were performed before vaccination and 1 month after dose 2, as described previously.3 The immunogenicity objective was to show noninferiority of the immune response to BNT162b2 in 12-to-15-year-old participants as compared with that in 16-to-25-year-old participants. Noninferiority was assessed among participants who had no evidence of previous SARS-CoV-2 infection with the use of the two-sided 95% confidence interval for the geometric mean ratio of SARS-CoV-2 50% neutralizing titers in 12-to-15-year-old participants as compared with 16-to-25-year-old participants 1 month after dose 2. BNT162b2 immunogenicity was evaluated in participants with and those without serologic or virologic evidence of previous SARS-CoV-2 infection. Corresponding end points were the geometric mean SARS-CoV-2 neutralizing titers at baseline (i.e., immediately before receipt of the first injection) and 1 month after dose 2 and geometric mean fold rises (GMFRs) in titers from baseline to 1 month after dose 2.

The efficacy of BNT162b2 against confirmed Covid-19 with an onset 7 or more days after dose 2 was summarized in participants who did not have evidence of previous SARS-CoV-2 infection, as well as in all vaccinated participants. Surveillance for potential Covid-19 cases was undertaken throughout the trial; if acute respiratory illness developed in a participant, the participant was tested for SARS-CoV-2. Methods for identifying SARS-CoV-2 infections and Covid-19 diagnoses are summarized in the Supplementary Appendix.

The safety population included all participants who received at least one dose of BNT162b2 or placebo. The reactogenicity subset included all 12-to-15-year-old participants and a subset of 16-to-25-year-old participants (those who received an e-diary to record reactogenicity events). Safety end points are presented descriptively as counts, percentages, and associated Clopper–Pearson two-sided 95% confidence intervals, with adverse events and serious adverse events described according to terms in the Medical Dictionary for Regulatory Activities, version 23.1, for each group.

Between October 15, 2020, and January 12, 2021, a total of 2306 adolescents 12 to 15 years of age were screened for inclusion, and 2264 underwent randomization across 29 U.S. sites; 2260 participants received injections, with 1131 receiving BNT162b2 and 1129 receiving placebo (Figure 1). More than 97% of the BNT162b2 recipients received dose 2. In the reactogenicity subset, all the 12-to-15-year-old participants were from the United States and the 16-to-25-year-old participants were recruited globally (Table 1). Although documented previous Covid-19 was an exclusion criterion, approximately 5% of the participants were SARS-CoV-2–positive at baseline, possibly because of previous asymptomatic infection. In the immunogenicity subset, all the participants in both age cohorts were from the United States. Among the 2260 participants who were 12 to 15 years of age, 51% were male, 86% were White, and 12% were Hispanic or Latinx. Overall, 1308 participants (58%) had at least 2 months of follow-up after their second vaccine dose. The trial populations are summarized in Table S1 in the Supplementary Appendix.

United States. Among the 2260 participants who were 12 to 15 years of age, 51% were male, 86% were White, and 12% were Hispanic or Latinx. Overall, 1308 participants (58%) had at least 2 months of follow-up after their second vaccine dose. The trial populations are summarized in Table S1 in the Supplementary Appendix. In both age cohorts, BNT162b2 recipients reported more local and systemic events than placebo recipients (Figure 2). Local and systemic events were generally mild to moderate in severity, reported at similar frequencies in both age cohorts, and typically resolved within 1 or 2 days. In both age cohorts, injection-site pain was the most common local reaction. Severe injection-site pain after any BNT162b2 dose was reported in 1.5% of 12-to-15-year-old participants and in 3.4% of 16-to-25-year-old participants; no severe pain was reported after placebo administration.

y resolved within 1 or 2 days. In both age cohorts, injection-site pain was the most common local reaction. Severe injection-site pain after any BNT162b2 dose was reported in 1.5% of 12-to-15-year-old participants and in 3.4% of 16-to-25-year-old participants; no severe pain was reported after placebo administration. In both age cohorts, headache and fatigue were the most frequently reported systemic events. After BNT162b2 injection, severe headache and severe fatigue were reported in a lower percentage of 12-to-15-year-old participants than of 16-to-25-year-old participants. Fever (oral body temperature, ≥38°C) occurred after dose 2 of BNT162b2 in 20% of 12-to-15-year-old recipients and in 17% of 16-to-25-year-old recipients. The use of antipyretic agents was slightly more frequent among BNT162b2 recipients who were 12 to 15 years of age than among those who were 16 to 25 years of age (37% vs. 32% after dose 1, and 51% vs. 46% after dose 2). Fever with a temperature higher than 40°C occurred in 1 (0.1%) of the 12-to-15-year-old participants 1 day after BNT162b2 dose 1. In general, systemic events were reported more often after BNT162b2 dose 2 than after dose 1. No differences in reactogenicity were noted between participants who were SARS-CoV-2–positive at baseline and those who were SARS-CoV-2–negative at baseline (Fig. S1).

-to-15-year-old participants 1 day after BNT162b2 dose 1. In general, systemic events were reported more often after BNT162b2 dose 2 than after dose 1. No differences in reactogenicity were noted between participants who were SARS-CoV-2–positive at baseline and those who were SARS-CoV-2–negative at baseline (Fig. S1). Among 12-to-15-year-old participants, adverse events occurring from dose 1 through 1 month after dose 2 were reported by 6% of BNT162b2 and placebo recipients; slightly more BNT162b2 recipients than placebo recipients reported related adverse events (3% vs. 2%) (Table S2). Among 16-to-25-year-old BNT162b2 recipients, 11% reported any adverse event and 6% had vaccine-related adverse events. Among BNT162b2 recipients, severe adverse events were reported in 0.6% of those who were 12 to 15 years of age and in 1.7% of those who were 16 to 25 years of age.

dverse events (3% vs. 2%) (Table S2). Among 16-to-25-year-old BNT162b2 recipients, 11% reported any adverse event and 6% had vaccine-related adverse events. Among BNT162b2 recipients, severe adverse events were reported in 0.6% of those who were 12 to 15 years of age and in 1.7% of those who were 16 to 25 years of age. One BNT162b2 recipient in the 12-to-15-year-old cohort discontinued vaccination because of a vaccine-related adverse event: a temperature greater than 40°C (described above) in a 14-year-old boy who was SARS-CoV-2–negative at baseline, had no reported medical history, and had no other symptoms. He received BNT162b2 dose 1 and had fever (temperature, 40.4°C) 1 day after vaccination, which resolved 2 days later. The participant did not receive dose 2 but remained in the trial for safety follow-up. One BNT162b2 recipient in the 16-to-25-year-old cohort discontinued vaccination because of severe vaccine-related injection-site pain and headache, both of which were reported 1 day after dose 1 and resolved within 1 day. Lymphadenopathy was reported in 9 of 1131 BNT162b2 recipients (0.8%) and in 2 of 1129 placebo recipients (0.2%) who were 12 to 15 years of age, as compared with in 1 of 536 BNT162b2 recipients (0.2%) and in no placebo recipients who were 16 to 25 years of age. Appendicitis was reported in 2 participants: 1 BNT162b2 recipient in the 16-to-25-year-old cohort and 1 placebo recipient in the 12-to-15-year-old cohort. No thromboses or hypersensitivity adverse events or vaccine-related anaphylaxis was seen. Few participants in any cohort (≤0.4% through 1 month after dose 2) had serious adverse events, and none were considered by the investigators to have been vaccine-related. No deaths were reported.

in the 12-to-15-year-old cohort. No thromboses or hypersensitivity adverse events or vaccine-related anaphylaxis was seen. Few participants in any cohort (≤0.4% through 1 month after dose 2) had serious adverse events, and none were considered by the investigators to have been vaccine-related. No deaths were reported. The immune response to BNT162b2 in 12-to-15-year-old adolescents was noninferior to that observed in 16-to-25-year-old young adults. The geometric mean ratio of the BNT162b2 neutralizing geometric mean titer in 12-to-15-year-old participants to that in 16-to-25-year-old participants 1 month after dose 2 was 1.76 (95% confidence interval [CI], 1.47 to 2.10) (Table 2), which met the noninferiority criterion (i.e., a lower boundary of the two-sided 95% confidence interval of >0.67). The lower boundary of the two-sided 95% confidence interval for the geometric mean ratio was greater than 1, indicating a greater response in adolescents than in young adults.

CI], 1.47 to 2.10) (Table 2), which met the noninferiority criterion (i.e., a lower boundary of the two-sided 95% confidence interval of >0.67). The lower boundary of the two-sided 95% confidence interval for the geometric mean ratio was greater than 1, indicating a greater response in adolescents than in young adults. Among all participants regardless of serologic evidence of previous SARS-CoV-2 infection, the serum-neutralizing geometric mean titer 1 month after BNT162b2 dose 2 was 1283.0 in the 12-to-15-year-old cohort and 730.8 in the 16-to-25-year-old cohort (Fig. S2). The corresponding geometric mean titers at 1 month among placebo recipients were 15.1 and 10.7. Substantial increases in the 50% neutralizing titer from baseline were observed, with GMFRs from baseline to 1 month after dose 2 of 118.3 among 12-to-15-year-old participants and 71.2 among 16-to-25-year-old participants. The corresponding GMFRs among placebo recipients were 1.4 and 1.1.

cipients were 15.1 and 10.7. Substantial increases in the 50% neutralizing titer from baseline were observed, with GMFRs from baseline to 1 month after dose 2 of 118.3 among 12-to-15-year-old participants and 71.2 among 16-to-25-year-old participants. The corresponding GMFRs among placebo recipients were 1.4 and 1.1. Among the 1983 participants in the 12-to-15-year-old cohort who could be evaluated and did not have evidence of previous SARS-CoV-2 infection, no cases of Covid-19 with an onset of 7 or more days after dose 2 were observed among BNT162b2 recipients and 16 cases were observed among placebo recipients, which corresponded to an observed vaccine efficacy of 100% (95% CI, 75.3 to 100) (Table 3). Similarly, in the group that included all 2229 participants in the 12-to-15-year-old cohort who could be evaluated, regardless of whether they had evidence of previous SARS-CoV-2 infection, vaccine efficacy from 7 days after dose 2 was 100% (95% CI, 78.1 to 100), with no Covid-19 cases observed among BNT162b2 recipients and 18 cases observed among placebo recipients. After dose 1 and before dose 2, there were 3 Covid-19 cases noted (within 11 days after dose 1) among BNT162b2 recipients, as compared with 12 cases among placebo recipients (vaccine efficacy, 75%; 95% CI, 7.6 to 95.5) (Table S3). No cases of severe Covid-19 were observed in this age cohort.

In both age cohorts, BNT162b2 recipients reported more local and systemic events than placebo recipients (Figure 2). Local and systemic events were generally mild to moderate in severity, reported at similar frequencies in both age cohorts, and typically resolved within 1 or 2 days. In both age cohorts, injection-site pain was the most common local reaction. Severe injection-site pain after any BNT162b2 dose was reported in 1.5% of 12-to-15-year-old participants and in 3.4% of 16-to-25-year-old participants; no severe pain was reported after placebo administration. In both age cohorts, headache and fatigue were the most frequently reported systemic events. After BNT162b2 injection, severe headache and severe fatigue were reported in a lower percentage of 12-to-15-year-old participants than of 16-to-25-year-old participants. Fever (oral body temperature, ≥38°C) occurred after dose 2 of BNT162b2 in 20% of 12-to-15-year-old recipients and in 17% of 16-to-25-year-old recipients. The use of antipyretic agents was slightly more frequent among BNT162b2 recipients who were 12 to 15 years of age than among those who were 16 to 25 years of age (37% vs. 32% after dose 1, and 51% vs. 46% after dose 2). Fever with a temperature higher than 40°C occurred in 1 (0.1%) of the 12-to-15-year-old participants 1 day after BNT162b2 dose 1. In general, systemic events were reported more often after BNT162b2 dose 2 than after dose 1. No differences in reactogenicity were noted between participants who were SARS-CoV-2–positive at baseline and those who were SARS-CoV-2–negative at baseline (Fig. S1).

Among 12-to-15-year-old participants, adverse events occurring from dose 1 through 1 month after dose 2 were reported by 6% of BNT162b2 and placebo recipients; slightly more BNT162b2 recipients than placebo recipients reported related adverse events (3% vs. 2%) (Table S2). Among 16-to-25-year-old BNT162b2 recipients, 11% reported any adverse event and 6% had vaccine-related adverse events. Among BNT162b2 recipients, severe adverse events were reported in 0.6% of those who were 12 to 15 years of age and in 1.7% of those who were 16 to 25 years of age.

The immune response to BNT162b2 in 12-to-15-year-old adolescents was noninferior to that observed in 16-to-25-year-old young adults. The geometric mean ratio of the BNT162b2 neutralizing geometric mean titer in 12-to-15-year-old participants to that in 16-to-25-year-old participants 1 month after dose 2 was 1.76 (95% confidence interval [CI], 1.47 to 2.10) (Table 2), which met the noninferiority criterion (i.e., a lower boundary of the two-sided 95% confidence interval of >0.67). The lower boundary of the two-sided 95% confidence interval for the geometric mean ratio was greater than 1, indicating a greater response in adolescents than in young adults. Among all participants regardless of serologic evidence of previous SARS-CoV-2 infection, the serum-neutralizing geometric mean titer 1 month after BNT162b2 dose 2 was 1283.0 in the 12-to-15-year-old cohort and 730.8 in the 16-to-25-year-old cohort (Fig. S2). The corresponding geometric mean titers at 1 month among placebo recipients were 15.1 and 10.7. Substantial increases in the 50% neutralizing titer from baseline were observed, with GMFRs from baseline to 1 month after dose 2 of 118.3 among 12-to-15-year-old participants and 71.2 among 16-to-25-year-old participants. The corresponding GMFRs among placebo recipients were 1.4 and 1.1.

Among the 1983 participants in the 12-to-15-year-old cohort who could be evaluated and did not have evidence of previous SARS-CoV-2 infection, no cases of Covid-19 with an onset of 7 or more days after dose 2 were observed among BNT162b2 recipients and 16 cases were observed among placebo recipients, which corresponded to an observed vaccine efficacy of 100% (95% CI, 75.3 to 100) (Table 3). Similarly, in the group that included all 2229 participants in the 12-to-15-year-old cohort who could be evaluated, regardless of whether they had evidence of previous SARS-CoV-2 infection, vaccine efficacy from 7 days after dose 2 was 100% (95% CI, 78.1 to 100), with no Covid-19 cases observed among BNT162b2 recipients and 18 cases observed among placebo recipients. After dose 1 and before dose 2, there were 3 Covid-19 cases noted (within 11 days after dose 1) among BNT162b2 recipients, as compared with 12 cases among placebo recipients (vaccine efficacy, 75%; 95% CI, 7.6 to 95.5) (Table S3). No cases of severe Covid-19 were observed in this age cohort.

A two-dose regimen of 30 μg of BNT162b2 administered 21 days apart to adolescents 12 to 15 years of age was safe and immunogenic and resulted in an observed vaccine efficacy of 100% against Covid-19 from 7 days after dose 2. BNT162b2 elicited a high immune response in adults,3 which translated to a 95% vaccine efficacy among participants in the phase 2–3 trial who were 16 years of age or older.5 Noninferiority of immunogenicity in 12-to-15-year-old adolescents, as shown in our trial, was initially planned as the primary assessment of vaccine effectiveness through “immunobridging,” an approach in which the effectiveness of a vaccine is inferred from immunogenicity data. The efficacy analysis was descriptive because a sufficient number of Covid-19 cases was not anticipated. However, given the number of cases and the precision of vaccine efficacy estimates, the vaccine efficacy in this trial provides a high level of certainty about the efficacy results. The lower limit of the 95% confidence interval for vaccine efficacy, which was greater than 75%, provides substantial evidence of efficacy in this age group and is consistent with the high efficacy previously reported in participants 16 years of age or older.5 Although BNT162b2 is a two-dose regimen, early protection after a single dose has been reported in clinical trials and on the basis of real-world data.5,19,20 It is reassuring that early protection is also observed in this age group, given the important public health implications for pandemic control.

of age or older.5 Although BNT162b2 is a two-dose regimen, early protection after a single dose has been reported in clinical trials and on the basis of real-world data.5,19,20 It is reassuring that early protection is also observed in this age group, given the important public health implications for pandemic control. Evaluation of BNT162b2 in younger adolescents was undertaken for several reasons. The incidence of Covid-19 is reported to be higher among 12-to-17-year-old adolescents than among younger children.21 In addition, children, especially from low-income families, have been negatively affected by the lack of in-person learning during the pandemic.17,18 Therefore, a demonstration of efficacy and safety in 12-to-15-year-old adolescents is important in order to expand the emergency use authorization to include children 12 years of age or older and make a critical step toward achieving herd immunity. Finally, the favorable safety and side-effect profile and high efficacy, along with the acceptable risk-to-benefit ratio in adolescents, now justify vaccine evaluation in younger age groups.22

ergency use authorization to include children 12 years of age or older and make a critical step toward achieving herd immunity. Finally, the favorable safety and side-effect profile and high efficacy, along with the acceptable risk-to-benefit ratio in adolescents, now justify vaccine evaluation in younger age groups.22 The favorable safety profile of BNT162b2, which was seen in adults in the pivotal trial and through ongoing pharmacovigilance after vaccine introduction, was also observed in 12-to-15-year-old recipients.5,23 Adherence was high, with more than 97% of BNT162b2 recipients receiving dose 2. As previously reported for vaccine recipients 16 years of age or older, systemic events in 12-to-15-year-old BNT162b2 recipients were reported more often after dose 2 than after dose 1.5 Antipyretic use after both doses was slightly higher in the 12-to-15-year-old cohort than in the 16-to-25-year-old cohort. This favorable safety profile is important, because a precedent exists for vaccines being increasingly reactogenic when administered to younger people. In the small percentage of participants who were SARS-CoV-2–positive at baseline, no differences in reactogenicity from those who were SARS-CoV-2–negative at baseline were noted, which supports immunization without screening for evidence of previous SARS-CoV-2 infection.

reactogenic when administered to younger people. In the small percentage of participants who were SARS-CoV-2–positive at baseline, no differences in reactogenicity from those who were SARS-CoV-2–negative at baseline were noted, which supports immunization without screening for evidence of previous SARS-CoV-2 infection. These results have several implications. Vaccination of adolescents is likely to confer the direct benefit of preventing disease along with indirect benefits, including community protection.24 Although children generally have a lower burden of symptomatic Covid-19 than adults, schools, youth sports, and other community gatherings may represent important sources of ongoing outbreaks and transmission, despite high rates of adult immunization.13,14,25 Vaccination of adolescents will allow them to reintegrate into society and resume in-person learning safely, which are especially important outcomes given the severe mental health effects of the Covid-19 pandemic on this group.18,22,26 Recent real-world data suggest that BNT162b2 prevents asymptomatic infection.19,27 Given the observed immunogenicity and efficacy, it is likely that vaccination will also prevent asymptomatic infection in children, thereby broadening community protection.

l health effects of the Covid-19 pandemic on this group.18,22,26 Recent real-world data suggest that BNT162b2 prevents asymptomatic infection.19,27 Given the observed immunogenicity and efficacy, it is likely that vaccination will also prevent asymptomatic infection in children, thereby broadening community protection. This analysis has some limitations. The efficacy analysis was prespecified as descriptive because an accurate sample size to assess vaccine efficacy could not be calculated before the start of the trial, given uncertainties about the incidence of SARS-CoV-2 infection. Therefore, the primary basis for the establishment of efficacy in 12-to-15-year-old adolescents was a neutralizing antibody response that was found to be noninferior to that in vaccine recipients 16 years of age or older, for whom efficacy had been shown.5 This report includes safety data through 1 month of follow-up after dose 2 for some participants. Data on longer-term safety and the duration of efficacy and antibody responses in children are not yet available.

to be noninferior to that in vaccine recipients 16 years of age or older, for whom efficacy had been shown.5 This report includes safety data through 1 month of follow-up after dose 2 for some participants. Data on longer-term safety and the duration of efficacy and antibody responses in children are not yet available. Although racial and ethnic diversity was lower among the 12-to-15-year-old participants than among those who were 16 years of age or older, vaccine efficacy in the latter age cohort is consistent among racial and ethnic subgroups,5 and a similar pattern is likely in the younger cohort. All 12-to-15-year-old participants in this trial were enrolled at U.S. sites, whereas the 16-to-25-year-old participants were recruited globally. In the immunogenicity subset, however, all participants in both age cohorts were from the United States. The testing laboratory supply limitation resulted in fewer than anticipated participants in the immunogenicity analyses; however, even with the smaller sample size and lower power, the trial still established noninferiority of the immune response. Although some participants received other vaccinations during the trial period, we did not formally examine concomitant vaccination with BNT162b2 and other vaccines received during adolescence. These results do not determine whether BNT162b2 vaccination prevents asymptomatic infection or transmission of SARS-CoV-2; asymptomatic surveillance is ongoing in this age group.

ns during the trial period, we did not formally examine concomitant vaccination with BNT162b2 and other vaccines received during adolescence. These results do not determine whether BNT162b2 vaccination prevents asymptomatic infection or transmission of SARS-CoV-2; asymptomatic surveillance is ongoing in this age group. Given the safety, immune response, and efficacy of the BNT162b2 vaccine in adolescents 12 to 15 years of age reported in this analysis, studies are ongoing to evaluate these measures in younger children and in other special populations, such as pregnant women.