The BNT162b2 (Pfizer-BioNTech) mRNA COVID-19 vaccine was recommended by CDC’s Advisory
Committee on Immunization Practices for persons aged 12–15 years (referred to as adolescents
in this report) on May 12, 2021, and for children aged 5–11 years on November 2, 2021
(
1
–
4
). Real-world data on vaccine effectiveness (VE) in these age groups are needed, especially
because when the B.1.1.529 (Omicron) variant became predominant in the United States
in December 2021, early investigations of VE demonstrated a decline in protection
against symptomatic infection for adolescents aged 12–15 years and adults* (
5
). The PROTECT
†
prospective cohort of 1,364 children and adolescents aged 5–15 years was tested weekly
for SARS-CoV-2, irrespective of symptoms, and upon COVID-19–associated illness during
July 25, 2021–February 12, 2022. Among unvaccinated participants (i.e., those who
had received no COVID-19 vaccine doses) with any laboratory-confirmed SARS-CoV-2 infection,
those with B.1.617.2 (Delta) variant infections were more likely to report COVID-19
symptoms (66%) than were those with Omicron infections (49%). Among fully vaccinated
children aged 5–11 years, VE against any symptomatic and asymptomatic Omicron infection
14–82 days (the longest interval after dose 2 in this age group) after receipt of
dose 2 of the Pfizer-BioNTech vaccine was 31% (95% CI = 9%–48%), adjusted for sociodemographic
characteristics, health information, frequency of social contact, mask use, location,
and local virus circulation. Among adolescents aged 12–15 years, adjusted VE 14–149
days after dose 2 was 87% (95% CI = 49%–97%) against symptomatic and asymptomatic
Delta infection and 59% (95% CI = 22%–79%) against Omicron infection. Fully vaccinated
participants with Omicron infection spent an average of one half day less sick in
bed than did unvaccinated participants with Omicron infection. All eligible children
and adolescents should remain up to date with recommended COVID-19 vaccinations.
PROTECT is a prospective cohort study monitoring SARS-CoV-2 infections among participants
aged 6 months–17 years in jurisdictions in four states (Arizona, Florida, Texas, and
Utah), initiated in July 2021 (
6
). Upon enrollment, parents or legal guardians provided the participants’ demographic,
health, vaccination history, and prior SARS-CoV-2 infection information; the number
of hours and percentage of time participants wore masks in school and in the community
were reported monthly.
§
Vaccination was verified by vaccine cards, electronic medical records, and state immunization
registries. Active surveillance for SARS-CoV-2 infection and any COVID-19–associated
symptoms
¶
within the preceding 7 days occurred through weekly submission of a survey and nasal
swab for reverse transcription–polymerase chain reaction testing and viral whole genome
sequencing.** Specific symptoms and duration, hours of school missed because of illness,
and receipt of medical care were documented through the electronic surveys.
For the calculation of VE, person-time for adolescents aged 12–15 years began at the
start of active surveillance on July 25, 2021, and ended February 12, 2022, or, for
adolescents eligible for a third (booster) dose (≥5 months after second mRNA vaccine
dose receipt), person-time ended when a booster dose was authorized on January 3,
2022.
††
For children aged 5–11 years, person-time for Omicron models began 6 weeks after the
Pfizer-BioNTech vaccine was recommended on November 2, 2021, and ended February 12,
2022. COVID-19 characteristics and comparisons between Delta and Omicron infections
were assessed. Cox proportional hazards models with time-varying vaccination status
were used to calculate hazard ratios of unvaccinated to vaccinated participants with
no prior SARS-CoV-2 infection (≥14 days after receipt of a second Pfizer-BioNTech
vaccine dose), weighted for inverse probability of vaccination using sociodemographic
characteristics, health information, frequency of social contact, mask use, location,
and local virus circulation. Characteristics of Omicron infections among vaccinated
and unvaccinated participants were also compared.
§§
All analyses were conducted using SAS software (version 9.4; SAS Institute) or R software
(version 4.1.2; R Foundation). This study was reviewed by CDC and approved by the
institutional review boards at participating sites or under a reliance agreement with
Abt Associates institutional review board and was conducted consistent with applicable
federal law and CDC policy.
¶¶
The study sample comprised 1,364 participants, including 1,052 (77%) children aged
5–11 years and 312 (23%) adolescents aged 12–15 years (Table 1).*** Overall, 76% of
participants lived in Arizona, 52% were female, 76% were White, 34% were Hispanic,
and 10% had at least one chronic medical condition. Of 381 SARS-CoV-2 infections among
children aged 5–11 years, and 127 infections among adolescents aged 12–15 years, 352
(93%) and 97 (76%), respectively, were Omicron infections.
TABLE 1
Characteristics of children and adolescents aged 5–15 years in the PROTECT* Pfizer-BioNTech
COVID-19 vaccine effectiveness cohort — four states, July 2021–February 2022
Characteristic
All participants, no. (column %)
COVID-19 vaccination status, no. (row %)
P-value§
All SARS-CoV-2 infections, no. (row %)
P-value§
Unvaccinated
≥1 dose†
Yes¶
No
All participants
1,364
386 (28.3)
978 (71.7)
—
508 (37.2)
856 (62.8)
—
Geographic location
Phoenix, Arizona
232 (17.0)
53 (22.8)
179 (77.2)
<0.001
87 (37.5)
145 (62.5)
<0.001
Tucson, Arizona
682 (50.0)
127 (18.6)
555 (81.4)
214 (31.4)
468 (68.6)
Other areas in Arizona
121 (8.9)
50 (41.3)
71 (58.7)
55 (45.5)
66 (54.5)
Miami, Florida
114 (8.4)
59 (51.8)
55 (48.2)
50 (43.9)
64 (56.1)
Temple, Texas
84 (6.2)
41 (48.8)
43 (51.2)
47 (56.0)
37 (44.0)
Salt Lake City, Utah
131 (9.6)
56 (42.7)
75 (57.3)
55 (42.0)
76 (58.0)
Age group, yrs
5–11
1,052 (77.1)
301 (28.6)
751 (71.4)
0.637
381 (36.2)
671 (63.8)
0.150
12–15
312 (22.9)
85 (27.2)
227 (72.8)
127 (40.7)
185 (59.3)
Sex
Female
713 (52.3)
203 (28.5)
510 (71.5)
0.883
254 (35.6)
459 (64.4)
0.196
Male
651 (47.7)
183 (28.1)
468 (71.9)
254 (39.0)
397 (61.0)
Ethnicity (all races)
Hispanic
469 (34.4)
158 (33.7)
311 (66.3)
0.264
163 (34.8)
306 (65.2)
0.312
Non-Hispanic
895 (65.6)
228 (25.5)
667 (74.5)
345 (38.5)
550 (61.5)
Race (all ethnicities)**
White
1,032 (75.7)
284 (27.5)
748 (72.5)
0.260
392 (38.0)
640 (62.0)
0.318
Other races
332 (24.3)
102 (30.7)
230 (69.3)
116 (34.9)
216 (65.1)
No. of children in household
1
204 (15.0)
52 (25.5)
152 (74.5)
0.334
66 (32.4)
138 (67.6)
0.117
≥2
1160 (85.0)
334 (28.8)
826 (71.2)
442 (38.1)
718 (61.9)
Chronic condition††
One or more
139 (10.2)
39 (28.1)
100 (71.9)
0.835
57 (41.0)
82 (59.0)
0.718
None
1,225 (89.8)
347 (28.3)
878 (71.7)
451 (36.8)
774 (63.2)
Daily medication§§
None
823 (60.3)
194 (50.3)
629 (64.3)
0.121
287 (56.5)
536 (62.6)
0.626
1
116 (8.5)
21 (5.4)
95 (9.7)
40 (7.9)
76 (8.9)
2
52 (3.8)
5 (1.3)
47 (4.8)
21 (4.1)
31 (3.6)
3
24 (1.8)
4 (1.0)
20 (2.0)
9 (1.8)
15 (1.8)
≥4
16 (1.2)
4 (1.0)
12 (1.2)
3 (0.6)
13 (1.5
Insurance
Private
1,052 (77.1)
247 (23.5)
805 (76.5)
<0.001
385 (36.6)
667 (63.4)
0.203
Public
197 (14.4)
78 (39.6)
119 (60.4)
84 (42.6)
113 (57.4)
None or did not respond
115 (8.4)
61 (53.0)
54 (47.0)
39 (33.9)
76 (66.1)
Average weekly social contact and mask use¶¶
Hours attending school, mean (SE)
37.9 (0.2)
36.1 (0.4)
38.5 (0.2)
<0.001
36.8 (0.3)
38.6 (0.2)
0.230
Percentage of school time masked, mean (SE)
78.0 (0.2)
59.9 (0.5)
83.8 (0.2)
<0.001
71.3 (0.4)
81.8 (0.2)
<0.001
Hours in community, mean (SE)
10.7 (0.1)
11.6 (0.2)
10.4 (0.1)
0.157
11.6 (0.1)
10.1 (0.1)
0.041
Percentage of community time masked, mean (SE)
64.3 (0.2)
47.6 (0.5)
69.6 (0.2)
<0.001
57.5 (0.4)
68.1 (0.3)
<0.001
Hours of COVID-19 exposure, mean (SE)
2.1 (0.1)
2.8 (0.2)
1.8 (0.1)
0.389
2.7 (0.1)
1.7 (0.1)
<0.001
* PROTECT (Pediatric Research Observing Trends and Exposures in COVID-19 Timelines)
is conducted in Phoenix and Tucson, Arizona; Miami, Florida; Temple, Texas; and Salt
Lake City, Utah.
† COVID-19 vaccination status excludes participants with reverse transcription–polymerase
chain reaction–confirmed SARS-CoV-2 infection during the first 13 days after receiving
their first vaccine dose (n = 36).
§ P-values comparing the percentage of persons vaccinated with those not vaccinated
and those with SARS-CoV-2 infections with those not infected by sociodemographic and
health categories were calculated using Pearson’s chi-square test. P-values for continuous
variables were calculated using the Kruskal-Wallis test.
¶ SARS-CoV-2 infections were detected by reverse transcription–polymerase chain reaction
testing.
** Among 332 children of other races, 111 (33.4%) identified as multiracial, 43 (13.0%)
as Asian, 28 (8%) as Black or African American, eight (2%) as American Indian or Alaskan
Native, three (1%) as Native Hawaiian or other Pacific Islander, and 14 (4%) as other;
race was missing, or respondent declined to answer for 125 (38%).
†† Chronic conditions included asthma or chronic lung disease, cancer, diabetes, heart
disease, hypertension, immunosuppression or autoimmune disorder, kidney disease, liver
disease, neurologic or neuromuscular disorder, or other chronic conditions.
§§
Number of daily medications prescribed by a physician were reported by participant
parent or legal guardian at study enrollment.
¶¶ Participants were asked to respond to monthly survey questions about COVID-19 exposure,
social contact, and mask use during the previous 7 days. The average of monthly responses
is calculated for each person. Average values across persons were compared according
to their vaccination and SARS-CoV-2 infection status at the time of this analysis.
School hours represent in-person school, child care, or before- or after-school care
attendance.
Participants who received ≥1 doses of vaccine were reported to have worn a mask during
84% of school hours and 70% of hours in the community, whereas unvaccinated children
were masked during 60% of school hours and 48% of hours in the community (p <0.001
for both). Lower percentages of masked time in school (71%) and in the community (58%)
were reported for participants with SARS-CoV-2 infection, compared with those of participants
who had no infection (82% and 68%, respectively) (p <0.001).
Among 252 unvaccinated participants with SARS-CoV-2 infections throughout the study
period, 112 (44%) were asymptomatic; unvaccinated participants with Omicron infections
were less likely to report COVID-19 symptoms (49%) than were those with Delta infections
(66%) (crude odds ratio = 0.5; 95% CI = 0.3–0.8) (Table 2). Overall, unvaccinated
participants with COVID-19 symptoms experienced an average of 6.9 days with illness
symptoms, spent an average of 1.9 days sick in bed, and missed an average of 24.0
hours of school because of illness. Omicron-associated COVID-19 symptoms lasted an
average of 5.3 days and resulted in an average of 18.8 hours of missed school, which
was 3.4 fewer days of symptoms (95% CI = –5.7 to –1.0) and 10.6 fewer hours of school
missed (95% CI = –18.6 to –2.7) than Delta-associated COVID-19.
TABLE 2
Comparison of SARS-CoV-2 Delta and Omicron variant infection characteristics among
unvaccinated children and adolescents aged 5–15 years and by Pfizer-BioNTech vaccination
status among Omicron infections — PROTECT* cohort study, four states, July 2021–February
2022
Characteristic
Participant vaccination status at time of infection
Unvaccinated
2 COVID-19 vaccine doses received 14–149 days before infection
Infections, no. (%)
OR or mean difference, Omicron versus Delta (95% CI)§
P-value§
Omicron No. (%)¶
Adjusted OR or mean difference, vaccinated versus unvaccinated (95% CI)**
P-value**
Total†
Delta
Omicron
Total participants, no. (%)
252 (100)
102 (100)
150 (100.0)
—
—
186 (100.0)
—
—
COVID-19–associated symptoms, no. (%)††
140 (55.6)
67 (65.7)
73 (48.7)
2.0 (1.20 to 3.45)
0.008
116 (62.4)
0.91 (0.48 to 1.59)
0.669
Febrile symptoms, no. (%)
§§
88 (62.9)
38 (56.7)
50 (68.5)
1.7 (0.83 to 3.31)
0.151
66 (56.9)
0.48 (0.23 to 1.03)
0.062
Received medical care, no. (%)
23 (16.4)
11 (16.4)
12 (16.4)
1.0 (0.41 to 2.45)
0.997
18 (15.5)
1.0 (0.43 to 2.48)
0.949
Total days of symptoms, mean (SE)
6.9 (6.7)
8.6 (8.0)
5.3 (5.4)
–3.4 (–5.7 to –1.0)
0.006
6.3 (3.9)
0.8 (–1.8 to 2.7)
0.426
Days spent sick in bed, mean (SE)
1.9 (2.4)
1.7 (2.7)
2.1 (2.1)
0.4 (–0.4 to 1.2)
0.322
1.4 (1.6)
–0.6 (–1.1 to –0.1)
0.016
Hours of missed school, mean (SE)
24.0 (23.5)
29.5 (24.1)
18.8 (21.8)
–10.6 (–18.6 to –2.7)
0.010
26.2 (17.5)
11.1 (4.6 to 17.6)
0.010
Abbreviation: OR = odds ratio.
* PROTECT (Pediatric Research Observing Trends and Exposures in COVID-19 Timelines)
is conducted in Phoenix and Tucson, Arizona; Miami, Florida; Temple, Texas; and Salt
Lake City, Utah.
† Includes all participants aged 5–15 years, and infections that occurred at any time
during the cohort study (July 25, 2021–February 12, 2022). However, of 275 total infections
among unvaccinated participants, only 252 completed a post-illness survey capturing
symptoms.
§ Severity of infection, comparing Delta infections as the referent group with Omicron
infections, was assessed by variant type among unvaccinated children and adolescents.
Logistic and linear regression models were used for dichotomous and continuous outcome
measures, respectively. P-values <0.05 were considered statistically significant.
¶ Of 198 total infections in persons that occurred 14–149 days after dose 2 receipt,
186 completed a post-illness survey to report symptoms. This excludes four Omicron
infections in persons aged 12–15 years with infection ≥150 days after receipt of dose
2.
** Severity of infection was assessed by vaccination status, comparing unvaccinated
children as the referent group with children vaccinated 14–149 days earlier, among
Omicron infections. Comparison of vaccinated and unvaccinated participants with Delta
infections was not included because of the limited number of vaccinated children with
Delta infections. Logistic and linear regression models were used for dichotomous
and continuous outcome measures, respectively, weighted for inverse probability of
vaccination by site, sociodemographic characteristics, health information, and knowledge,
attitudes, and practices regarding SARS-CoV-2 infection and vaccine.
†† COVID-19–associated illness signs and symptoms included fever >100°F (37.8°C),
chills, cough, shortness of breath, sore throat, diarrhea, muscle or body aches, change
in smell or taste; runny nose, fatigue or being run-down, decreased activity, and
irritability or crankiness were also included for nonverbal children.
§§
Febrile symptoms were defined as symptoms of feverishness or chills, or a measured
temperature >100.4°F (38°C).
Among the 1,052 participants aged 5–11 years, 682 (65%) received 2 vaccine doses,
69 (7%) received 1 dose, and 301 (29%) were unvaccinated. Adjusted VE against symptomatic
and asymptomatic Omicron infection 14–82 days after receipt of dose 2 (the longest
interval after dose 2 in this age group) was 31% (95% CI = 9%–48%) (Table 3).
TABLE 3
COVID-19 Pfizer-BioNTech vaccine effectiveness against asymptomatic or symptomatic
SARS-CoV-2 infection among children and adolescents aged 5–15 years, by time since
receipt of second vaccine dose and variant — PROTECT* cohort study, four states, July
2021–February 2022
Age group and COVID-19 vaccination status (no. of days since receipt of most recent
dose)
No. of contributing participants†
Total person-days
Median no. of days (IQR)
No. of SARS-CoV-2 infections§
VE, % (95% CI)
Unadjusted
Adjusted¶
Children aged 5–11 yrs
Omicron variant infections
Unvaccinated (referent)
336
13,801
41 (28 to 62)
137
—
—
2 doses (14–82 days)
640
29,996
53 (34 to 61)
184
47 (32 to 59)
31 (9 to 48)
Adolescents aged 12–15 yrs
Delta variant infections
Unvaccinated (referent)
139
9,786
65 (25 to 107)
23
—
—
2 doses (≥14 days)
193
23,575
142 (91 to 156)
7
87 (70 to 95)
81 (51 to 93)
2 doses (14–149 days)
188
16,517
97 (75 to 105)
3
93 (76 to 98)
87 (49 to 97)
2 doses (≥150 days)
138
7,058
57 (49 to 63)
4
67 (0 to 89)
60 (−35 to 88)
Omicron variant infections
Unvaccinated (referent)
76
3,001
37 (24 to 62)
38
—
—
2 doses (≥14 days)
192
5,432
22 (22 to 31)
18
64 (37 to 80)
59 (24 to 78)
2 doses (14–149 days)
65
2,623
42 (28 to 56)
14
62 (30 to 79)
59 (22 to 79)
2 doses (≥150 days)
134
2,809
22 (22 to 22)
4
74 (16 to 92)
62 (−28 to 89)
Abbreviations: SMD = standard mean difference; VE = vaccine effectiveness.
* PROTECT (Pediatric Research Observing Trends and Exposures in COVID-19 Timelines)
is conducted in Phoenix and Tucson, Arizona; Miami, Florida; Temple, Texas; and Salt
Lake City, Utah.
† Vaccination status varied with time, therefore, contributing participants in vaccination
categories do not equal the number of participants in the study because participants
could contribute to more than one vaccination category.
§ Of 275 SARS-CoV-2 infections among unvaccinated participants, 98 occurred among
children aged 5–11 years either before vaccine availability (n = 60) or were Delta
infections (n = 17) for whom VE was not calculated. Among vaccinated participants,
61 occurred after receipt of dose 1 and <14 days after dose 2; two children aged 5–11
years were vaccinated before authorization, and two had Delta infections among children
aged 5–11 years for whom VE was not calculated.
¶ Adjusted VE is inversely weighted for propensity to be vaccinated. Among children
aged 5–11 years, all covariates met balance criteria of SMD <0.2 after weighting for
the Delta variant model. For the Omicron variant model, all covariates met balance
criteria of SMD <0.2 after weighting, except local virus circulation and social (school
or community) mask use, which both changed the VE estimate by ≥5% when added to the
model, and thus remained in the final model as covariates. Among adolescents aged
12–15 years, all covariates met balance criteria of SMD <0.2 after weighting except
social mask use, which also changed the VE estimate by ≥5% when added to the Delta
variant model, and thus remained in the final model as a covariate. For the Omicron
variant model, all covariates met balance criteria of SMD <0.2 after weighting, except
local virus circulation, social (school or community) mask use, and number of medications.
Only local virus circulation changed the VE estimate by ≥5% when added to the model,
and thus remained in the final model as a covariate.
Among 312 adolescents aged 12–15 years, 212 (68%) received 2 vaccine doses, 15 (5%)
received 1 dose, and 85 (27%) were unvaccinated. The adjusted VE at 14–149 days after
receipt of dose 2 was 87% (95% CI = 49%–97%) against Delta infection and 59% (95%
CI = 22%–79%) against Omicron infection. Adjusted VE ≥150 days after dose 2 was 60%
against Delta infection and 62% against Omicron, with wide CIs that included zero.
Among 186 vaccinated participants with Omicron infections (174 [93%] in children aged
5–11 years and 13 [7%] in adolescents aged 12–15 years), 37.6% were asymptomatic;
those reporting COVID-19 symptoms spent 1.4 days in bed, which was 0.6 days fewer
than reported for unvaccinated participants (95% CI = –1.1 to –0.1) (Table 2), after
adjusting for the propensity to be vaccinated. Conversely, vaccinated participants
with Omicron infections stayed home from school 26.2 hours, an adjusted mean of 11
hours more than that reported for unvaccinated participants (95% CI = 4.6–17.6). Overall,
medical care–seeking was reported for 16.4% of unvaccinated participants with Omicron
infections and 15.5% of vaccinated participants, which was not significantly different.
Discussion
In this prospective cohort study of children and adolescents aged 5–15 years that
included routine weekly SARS-CoV-2 testing, irrespective of symptoms, 2 doses of Pfizer-BioNTech
vaccines were effective in preventing symptomatic and asymptomatic SARS-CoV-2 infections,
although effectiveness varied by variant. VE point estimates were highest against
Delta variant infections among adolescents aged 12–15 years and lowest against Omicron
variant infections among children aged 5–11 years.
The SARS-CoV-2 infections prevented by vaccination differed by variant. Approximately
one half (51%) of all Omicron infections were asymptomatic compared with approximately
one third (34%) of Delta infections. However, when children or adolescents experienced
symptomatic COVID-19, the illnesses disrupted life at home and school; on average
COVID-19 lasted 7 days, two of which were spent sick in bed, and resulted in 24 hours
of missed school.
Two doses of Pfizer-BioNTech vaccine received <5 months earlier were moderately effective
(31%) in preventing symptomatic and asymptomatic Omicron infection among children
aged 5–11 years and 59% effective among adolescents aged 12–15 years. The wide and
overlapping CIs indicate that these age-specific VE point estimates might not be significantly
different and are similar to a recent report of VE of 45%–51% for 2 doses, received
within 150 days, against Omicron COVID-19–associated emergency department and urgent
care visits among children and adolescents aged 5–15 years (
7
). Participants who were infected with Omicron despite receipt of 2 vaccine doses
spent an average of one half day less sick in bed than did unvaccinated participants
with Omicron infections. Also, similar to studies of children (
7
) and adults (
6
), among adolescents aged 12–15 years, point estimates for VE of 2 doses received
within the previous 150 days were lower against Omicron than Delta infections, although
these differences were not statistically significant.
The findings in this report are subject to at least five limitations. First, despite
the use of robust adjusted models previously applied in other cohort studies (
8
), VE estimates might have been biased by residual confounding due to other differences
between vaccinated and unvaccinated participants. For example, vaccinated participants
reported wearing face masks significantly more often at school and in the community
than did unvaccinated participants. Second, although PROTECT is among the largest
studies with routine weekly SARS-CoV-2 testing, the relatively small number of infections
within vaccination categories among certain age groups reduced precision of VE estimates.
Estimates of VE at ≥150 days after dose 2 had very wide CIs, and thus it is unclear
whether VE wanes with increased time since vaccination. Third, data were not available
to assess possible reasons that vaccinated participants with COVID-19 might have missed
more school than did unvaccinated participants despite unvaccinated participants reporting
more days sick in bed. Fourth, these interim estimates do not include separate analyses
of VE against asymptomatic infection and symptomatic infection at this time. Finally,
although this study was conducted in multiple sites and included more than 1,300 participants,
findings from the study sample might not be generalizable to all populations.
This study provides evidence that receipt of 2 doses of Pfizer-BioNTech vaccine is
effective in preventing both asymptomatic and symptomatic SARS-CoV-2 infection with
the Omicron variant among children and adolescents aged 5–15 years. All eligible children
and adolescents should remain up to date with recommended COVID-19 vaccinations.
Summary
What is already known about this topic?
Receipt of 2 doses of Pfizer-BioNTech COVID-19 vaccine has been shown to be effective
in preventing infection with the SARS-CoV-2 B.1.617.2 (Delta) variant in persons aged
≥12 years.
What is added by this report?
Children and adolescents aged 5–15 years were tested for SARS-CoV-2 weekly, irrespective
of symptoms, during July 2021–February 2022. Approximately one half of Omicron infections
in unvaccinated children and adolescents were asymptomatic. Two doses of Pfizer-BioNTech
COVID-19 vaccine reduced the risk of Omicron infection by 31% among children aged
5–11 years and by 59% among persons aged 12–15 years.
What are the implications for public health practice?
All eligible children and adolescents should remain up to date with recommended COVID-19
vaccinations.