Safety Monitoring of Bivalent COVID-19 mRNA Vaccine Booster Doses Among Persons Aged ≥12 Years — United States, August 31–October 23, 2022

Abstract

On August 31, 2022, the Food and Drug Administration (FDA) authorized bivalent formulations of BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) COVID-19 vaccines; these vaccines include mRNA encoding the spike protein from the original (ancestral) strain of SARS-CoV-2 (the virus that causes COVID-19) and from the B.1.1.529 (Omicron) variants BA.4 and BA.5 (BA.4/BA.5). These bivalent mRNA vaccines were authorized for use as a single booster dose ≥2 months after completion of primary series or monovalent booster vaccination; Pfizer-BioNTech bivalent booster was authorized for persons aged ≥12 years and Moderna for adults aged ≥18 years.*,† On September 1, 2022, the Advisory Committee on Immunization Practices (ACIP) recommended that all persons aged ≥12 years receive an age-appropriate bivalent mRNA booster dose.§ To characterize the safety of bivalent mRNA booster doses, CDC reviewed adverse events and health impacts reported after receipt of bivalent Pfizer-BioNTech and Moderna booster doses during August 31-October 23, 2022, to v-safe,¶ a voluntary smartphone-based U.S. safety surveillance system established by CDC to monitor adverse events after COVID-19 vaccination, and the Vaccine Adverse Event Reporting System (VAERS),** a U.S. passive vaccine safety surveillance system managed by CDC and FDA (1). During August 31-October 23, 2022, approximately 14.4 million persons aged ≥12 years received a bivalent Pfizer-BioNTech booster dose, and 8.2 million adults aged ≥18 years received a bivalent Moderna booster dose.†† Among the 211,959 registrants aged ≥12 years who reported receiving a bivalent booster dose to v-safe, injection site and systemic reactions were frequently reported in the week after vaccination (60.8% and 54.8%, respectively); fewer than 1% of v-safe registrants reported receiving medical care. VAERS received 5,542 reports of adverse events after bivalent booster vaccination among persons aged ≥12 years; 95.5% of reports were nonserious and 4.5% were serious events. Health care providers and patients can be reassured that adverse events reported after a bivalent booster dose are consistent with those reported after monovalent doses. Health impacts after COVID-19 vaccination are less frequent and less severe than those associated with COVID-19 illness (2).

Full text

Morbidity and Mortality Weekly Report
MMWR / November 4, 2022 / Vol. 71 / No. 44 1401
US Department of Health and Human Services/Centers for Disease Control and Prevention
Safety Monitoring of Bivalent COVID-19 mRNA Vaccine Booster Doses Among
Persons Aged ≥12 Years — United States, August 31–October 23, 2022
Anne M. Hause, PhD1; Paige Marquez, MSPH1; Bicheng Zhang, MS1; Tanya R. Myers, PhD1; Julianne Gee, MPH1; John R. Su, MD, PhD1;
Phillip G. Blanc, MD2; Alisha Thomas, MD2; Deborah Thompson, MD2; Tom T. Shimabukuro, MD1; David K. Shay, MD1
On August 31, 2022, the Food and Drug Administration
(FDA) authorized bivalent formulations of BNT162b2
(Pfizer-BioNTech) and mRNA-1273 (Moderna) COVID-19
vaccines; these vaccines include mRNA encoding the spike
protein from the original (ancestral) strain of SARS-CoV-2
(the virus that causes COVID-19) and from the B.1.1.529
(Omicron) variants BA.4 and BA.5 (BA.4/BA.5). These
bivalent mRNA vaccines were authorized for use as a single
booster dose ≥2 months after completion of primary series
or monovalent booster vaccination; Pfizer-BioNTech biva-
lent booster was authorized for persons aged ≥12 years and
Moderna for adults aged ≥18 years.*,† On September 1, 2022,
the Advisory Committee on Immunization Practices (ACIP)
recommended that all persons aged ≥12 years receive an age-
appropriate bivalent mRNA booster dose.§ To characterize
the safety of bivalent mRNA booster doses, CDC reviewed
adverse events and health impacts reported after receipt of
bivalent Pfizer-BioNTech and Moderna booster doses during
August 31–October 23, 2022, to v-safe,¶ a voluntary smart-
phone-based U.S. safety surveillance system established by
CDC to monitor adverse events after COVID-19 vaccination,
and the Vaccine Adverse Event Reporting System (VAERS),**
a U.S. passive vaccine safety surveillance system managed by
CDC and FDA (1). During August 31–October 23, 2022,
approximately 14.4 million persons aged ≥12 years received a
bivalent Pfizer-BioNTech booster dose, and 8.2 million adults
aged ≥18 years received a bivalent Moderna booster dose.††
Among the 211,959 registrants aged ≥12 years who reported
receiving a bivalent booster dose to v-safe, injection site and
systemic reactions were frequently reported in the week after
vaccination (60.8% and 54.8%, respectively); fewer than 1%
of v-safe registrants reported receiving medical care. VAERS
received 5,542 reports of adverse events after bivalent booster
vaccination among persons aged ≥12 years; 95.5% of reports
were nonserious and 4.5% were serious events. Health care
providers and patients can be reassured that adverse events
* https://www.fda.gov/media/150386/download
† https://www.fda.gov/media/144636/download
§ https://www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-
considerations-us.html
¶ https://vsafe.cdc.gov/en
** https://vaers.hhs.gov
†† https://covid.cdc.gov/covid-data-tracker/#vaccination-demographic (Accessed
October 23, 2022).
reported after a bivalent booster dose are consistent with
those reported after monovalent doses. Health impacts after
COVID-19 vaccination are less frequent and less severe than
those associated with COVID-19 illness (2).
The v-safe system allows existing registrants to report receipt
of a COVID-19 booster dose and new registrants to enter infor-
mation about all doses received; registrants can also indicate
whether any other vaccines were administered during the same
visit. On September 2, 2022, v-safe was modified to allow par-
ticipants to enter up to 6 doses of a COVID-19 vaccine. Health
surveys sent daily during the first week after administration
of each dose include questions about local injection site and
systemic reactions and health impacts experienced; registrants
can provide additional information about these reactions or
health impacts via free text message.§§ CDC’s v-safe call center
staff members contact registrants who indicate that medical
care was received after vaccination to request more informa-
tion; registrants are also encouraged to complete a VAERS
report, if indicated.
VAERS accepts reports of postvaccination adverse events
from health care providers, vaccine manufacturers, and mem-
bers of the public.¶¶ Signs and symptoms and diagnostic
findings in VAERS reports are assigned Medical Dictionary
for Regulatory Activities preferred terms (MedDRA PTs) by
VAERS staff members.*** Reports of serious events to VAERS
during August 31–October 23, 2022, were reviewed by CDC
physicians to form a consensus clinical impression based on
available data.††† Death certificates and autopsy reports were
requested for any report of death. CDC physicians reviewed
§§ Children and adolescents aged ≤15 years must be enrolled by a parent or
guardian. Health check-ins are sent via text messages that link to web-based
surveys on days 0–7 after vaccination; then weekly through 6 weeks after
vaccination; and then 3, 6, and 12 months after vaccination.
¶¶ Under emergency use authorization regulations, health care providers are
required to report certain adverse events after COVID-19 vaccination to
VAERS, including death (https://vaers.hhs.gov/faq.html). VAERS forms ask
for patient, vaccine, administration, and adverse event information. https://
vaers.hhs.gov/docs/VAERS%202.0_Checklist.pdf
*** Each VAERS report might be assigned more than one MedDRA PT. A
MedDRA-coded event does not indicate a medically confirmed diagnosis.
https://www.meddra.org/how-to-use/basics/hierarchy
††† VAERS reports are classified as serious (based on FDA C.F.R. Title 21) if
any of the following are reported: hospitalization, prolongation of
hospitalization, life-threatening illness, permanent disability, congenital
anomaly or birth defect, or death. https://www.accessdata.fda.gov/scripts/
cdrh/cfdocs/cfcfr/cfrsearch.cfm?fr

Morbidity and Mortality Weekly Report
1402 MMWR / November 4, 2022 / Vol. 71 / No. 44 US Department of Health and Human Services/Centers for Disease Control and Prevention
all available information for each decedent to form an impres-
sion about the cause of death. Using selected MedDRA PTs, a
search was performed to identify possible cases of myocarditis,
a rare adverse event that has been associated with mRNA
COVID-19 vaccines (2).
A bivalent booster dose in v-safe was defined as an age-
appropriate mRNA vaccine dose administered on or after
August 31, 2022, for registrants who had completed at least
a primary series (2 doses of Pfizer-BioNTech, Moderna, or
Novavax COVID-19 vaccine or 1 dose of Janssen [Johnson
& Johnson] vaccine). Local and systemic reactions and health
impacts reported during the week after a bivalent booster dose
vaccination were described for v-safe registrants aged ≥12 years
who received a bivalent booster dose during August 31–
October 23, 2022. VAERS adverse event reports after a bivalent
booster dose were described by serious and nonserious clas-
sification, demographic characteristics, and MedDRA PTs.
All analyses were conducted using SAS software (version 9.4;
SAS Institute). These surveillance activities were reviewed by
CDC and conducted consistent with applicable federal law
and CDC policy.§§§
Review of v-safe Data
During August 31–October 23, 2022, a total of 211,959 v-safe
registrants aged ≥12 years reported receiving an age-appropriate
bivalent booster dose (Table 1); 1,464 (0.7%) were aged
12–17 years, 68,592 (32.4%) were aged 18–49 years, 59,209
(27.9%) were aged 50–64 years, and 82.694 (39.0%) were aged
≥65 years. Most registrants indicated that a bivalent booster
dose was their fourth (96,241; 45.4%) or fifth (106,423;
50.2%) COVID-19 vaccine dose; 122,953 (58.0%) received
a Pfizer-BioNTech bivalent booster dose and 89,065 (42.0%)
received a Moderna bivalent booster dose. More than one third
(84,450; 39.8%) of registrants reported receiving at least one
other vaccination at the same visit as bivalent booster vaccina-
tion; 83,005 (98.3%) received influenza vaccine.
In the week after receipt of the bivalent booster dose, fre-
quency of reporting of local injection site reactions ranged
from 49.7% among adults aged ≥65 years to 72.9% among
adults aged 18–49 years; the prevalence of reported systemic
reactions ranged from 43.5% among adults aged ≥65 years to
67.9% among adults aged 18–49 years (Table 2). The most
frequently reported reactions among these age groups after
bivalent booster dose vaccination were injection site pain
(range = 45.0%–70.5%), fatigue (30.0%–53.1%), head-
ache (19.7%–42.8%), myalgia (20.3%–41.3%), and fever
(10.2%–26.3%).
§§§ 45 C.F.R. part 46, 21 C.F.R. part 56; 42 U.S.C. Sect. 241(d); 5 U.S.C. Sect.
552a; 44 U.S.C. Sect. 3501 et seq.
TABLE 1. Demographic and vaccination characteristics of persons
aged ≥12 years* who reported receipt of a bivalent Pfizer-BioNTech
or Moderna COVID-19 vaccine booster dose to v-safe† —
United States, August 31–October 23, 2022
Characteristic
Vaccine, no. (%)
Pfizer-
BioNTech
n = 122,953
Moderna
n = 89,006
Total
N = 211,959
Sex
Female 77,913 (63.4) 56,651 (63.7) 134,564 (63.5)
Male 44,031 (35.8) 31,697 (35.6) 75,728 (35.7)
Unknown 1,009 (0.8) 658 (0.7) 1,667 (0.8)
Age group, yrs
12–17 1,464 (1.2) NA 1,464 (0.7)
18–49 41,022 (33.4) 27,570 (31.0) 68,592 (32.4)
50–64 34,947 (28.4) 24,262 (27.3) 59,209 (27.9)
≥65 45,520 (37.0) 37,174 (41.8) 82,694 (39.0)
Ethnicity
Hispanic 6,967 (5.7) 4,765 (5.4) 11,732 (5.5)
Non-Hispanic 112,895 (91.8) 82,009 (92.1) 194,904 (92.0)
Unknown 3,091 (2.5) 2,232 (2.5) 5,323 (2.5)
Race
American Indian or Alaska Native 441 (0.4) 328 (0.4) 769 (0.4)
Asian 6,884 (5.6) 4,750 (5.3) 11,634 (5.5)
Black or African American 6,574 (5.4) 4,583 (5.2) 11,157 (5.3)
Native Hawaiian or other
Pacific Islander
241 (0.2) 145 (0.2) 386 (0.2)
White 102,535 (83.4) 74,984 (84.3) 177,519 (83.8)
Multiracial 2,518 (2.1) 1,667 (1.9) 4,185 (2.0)
Other 1,873 (1.5) 1,262 (1.4) 3,135 (1.5)
Unknown 1,887 (1.5) 1,287 (1.5) 3,174 (1.5)
Total no. of COVID-19 vaccine doses received
2 86 (0.1) 52 (0.1) 138 (0.1)
3 4,919 (4.0) 3,186 (3.6) 8,105 (3.8)
4 57,603 (46.9) 38,638 (43.4) 96,241 (45.4)
5 59,807 (48.6) 46,616 (52.4) 106,423 (50.2)
6 538 (0.4) 514 (0.6) 1,052 (0.5)
Vaccine co-administration§
Yes 51,713 (42.1) 32,737 (36.8) 84,450 (39.8)
No 71,240 (57.9) 56,269 (63.2) 127,509 (60.2)
Abbreviation: NA = not applicable.
* On August 31, 2022, the Food and Drug Administration authorized bivalent
formulations of Moderna and Pfizer-BioNTech COVID-19 vaccines for use as a
single booster dose ≥2 months after completing primary or booster
vaccination, Pfizer-BioNTech for persons aged ≥12 years and Moderna for
persons aged ≥18 years. In v-safe, a bivalent booster dose was defined as an
age-appropriate mRNA dose administered on or after August 31, 2022, for
registrants who completed a primary series (2 doses of Pfizer-BioNTech,
Moderna, or Novavax COVID-19 vaccine or 1 dose of Janssen).
† Includes registrants who completed at least one survey during days 0–7
postvaccination.
§ Other vaccines administered during the same visit.
Reported inability to complete normal daily activities ranged
from 10.6% among adults aged ≥65 years to 19.8% among
adults aged 18–49 years. Receipt of medical care was reported
by 0.8% of registrants; most received care via telehealth (0.3%)
or clinic (0.3%) appointment. Hospitalization was reported by
55 (0.03%) registrants. Among 45 registrants with information
about the hospitalization available from the v-safe call center or
free text message response, 29 indicated that the hospitalization

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US Department of Health and Human Services/Centers for Disease Control and Prevention
TABLE 2. Adverse reactions and health impacts reported to v-safe for persons aged ≥12 years* who received a bivalent Pfizer-BioNTech or
Moderna COVID-19 vaccine booster dose — United States, August 31–October 23, 2022
Event
% Reporting reaction/health impact after vaccination, by age group, yrs†
12–17
n = 1,464
18–49
n = 68,592
50–64
n = 59,209
≥65
n = 82,694
Total
N = 211,959
Any injection site reaction 68.7 72.9 62.0 49.7 60.8
Itching 4.6 8.9 7.8 6.9 7.8
Pain 66.9 70.5 58.8 45.0 57.3
Redness 8.5 10.8 9.1 7.6 9.1
Swelling or hardness 13.7 18.4 14.7 9.9 14.0
Any systemic reaction 59.8 67.9 55.2 43.5 54.8
Abdominal pain 6.4 5.5 3.6 2.1 3.6
Myalgia 33.6 41.3 29.0 20.3 29.6
Chills 19.6 20.6 13.7 9.1 14.2
Fatigue 45.2 53.1 40.0 30.0 40.4
Fever 26.3 23.7 16.6 10.2 16.4
Headache 36.3 42.8 31.5 19.7 30.6
Joint pain 14.5 21.7 16.8 11.1 16.1
Nausea 12.4 12.9 7.9 4.5 8.2
Diarrhea 3.0 6.7 5.4 3.8 5.2
Rash 1.4 1.3 1.1 0.9 1.1
Vomiting 2.5 1.2 0.6 0.4 0.7
Any health impact 26.8 24.2 17.3 11.6 17.3
Unable to perform normal daily activities 18.4 19.8 14.7 10.6 14.8
Unable to attend school or work 15.6 11.3 6.0 1.6 6.1
Needed medical care 1.2 0.9 0.7 0.8 0.8
Telehealth 0.2 0.3 0.2 0.2 0.3
Clinic 0.8 0.4 0.3 0.3 0.3
Emergency visit 0.1 0.1 0.1 0.1 0.1
Hospitalization 0 0 0 0 0
* On August 31, 2022, the Food and Drug Administration authorized bivalent formulations of Moderna and Pfizer-BioNTech COVID-19 vaccines for use as a single
booster dose ≥2 months after completing primary or booster vaccination, Pfizer-BioNTech for persons aged ≥12 years and Moderna for adults aged ≥18 years. In
v-safe, a bivalent booster was defined as an age-appropriate mRNA dose administered on or after August 31, 2022, for registrants who completed a primary series
(2 doses of Pfizer-BioNTech, Moderna, or Novavax COVID-19 vaccine or 1 dose of Janssen).
† Percentage of registrants who reported a reaction or health impact at least once during days 0–7 postvaccination.
was unrelated to vaccination, 13 completed a VAERS report,
and three did not wish to complete a VAERS report.
Review of VAERS Data
During August 31–October 23, 2022, VAERS received
and processed 5,542 reports of adverse events among per-
sons aged ≥12 years who reported receiving a bivalent booster
dose (Table 3).¶¶¶ The median recipient age was 60 years
(range = 12–101) and 3,559 (64.2%) were female; 939 (16.9%)
reports indicated at least one other vaccine was received at the
same visit as booster vaccination, of which influenza vaccine
was most commonly co-administered (852; 90.7%).
Events related to vaccination errors (e.g., incorrect product
formulation administered, incorrect dose administered, under-
dose, or wrong product administered) were commonly reported
(1,913; 34.5%); among 877 reports of vaccination errors after
receipt of Pfizer-BioNTech and 1,037 reports after receipt of
¶¶¶ Processed VAERS reports are those that have been coded using MedDRA,
deduplicated, and undergone standard quality assurance and quality control review.
Moderna bivalent booster doses, 225 (11.8%) reports indicated
that an adverse health event had occurred.
Most VAERS reports (5,291; 95.5%) were classified as
nonserious, including 2,762 (94.3%) after Pfizer-BioNTech
and 2,530 (96.8%) after Moderna bivalent booster vaccina-
tion. The most commonly reported events among nonserious
reports were headache (628; 11.9%), fatigue (575; 10.9%),
fever (561; 10.6%), pain (524; 9.9%), and chills (459; 8.7%).
Among 251 VAERS reports classified as serious, five were
reports of myocarditis, four were reports of pericarditis, and
20 were reports of COVID-19 disease. The age range of those
who experienced myocarditis or pericarditis was 12–78 years
and 46–78 years, respectively. Thirty-six deaths were reported;
median age of decedents was 71 years (range = 46–98 years).
For the four reports of death with sufficient information for
review at the time of this report, cause of death included cardiac
arrest, dementia, metastatic prostate cancer, and myocardial
infarction. CDC has requested medical and vital records for
the remaining decedents.

Morbidity and Mortality Weekly Report
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TABLE 3. Events* reported to the Vaccine Adverse Event Reporting System for persons aged ≥12 years† after receipt of a bivalent Pfizer-BioNTech
or Moderna COVID-19 vaccine booster dose — United States, August 31–October 23, 2022
Adverse events
Vaccine, no. reporting (%)
Pfizer-BioNTech Moderna Total§
Total 2,928 2,615 5,542
Vaccination errors¶877 (30.0) 1,037 (39.7) 1,913 (34.5)
Error without adverse health event 717 (81.8) 972 (93.7) 1,688 (88.2)
Error with adverse health event** 160 (18.2) 65 (6.3) 225 (11.8)
Error with nonserious health event†† 157 (17.9) 61 (5.9) 218 (11.4)
Error with serious health event 3 (0.3) 4 (0.4) 7 (0.4)
Nonserious reports§§,¶¶ 2,762 (94.3) 2,530 (96.8) 5,291 (95.5)
Headache 343 (12.4) 285 (11.3) 628 (11.9)
Fatigue 318 (11.5) 257 (10.2) 575 (10.9)
Fever 299 (10.8) 262 (10.4) 561 (10.6)
Pain 293 (10.6) 231 (9.1) 524 (9.9)
Chills 254 (9.2) 205 (8.1) 459 (8.7)
Pain in extremity 209 (7.8) 167 (6.6) 376 (7.1)
Nausea 213 (7.7) 144 (5.7) 357 (6.8)
Dizziness 212 (7.7) 135 (5.3) 347 (6.6)
Injection site pain 138 (5.0) 121 (4.8) 259 (4.9)
COVID-19 169 (6.1) 89 (3.5) 258 (4.9)
Serious reports***,††† 166 (5.7) 85 (3.3) 251 (4.5)
Allergic reaction/Anaphylaxis 6 2 8
Appendicitis 4 1 5
Arrythmia 8 5 13
Atrial fibrillation 5 4 9
Atrioventricular node block, second or third degree 2 0 2
Supraventricular tachycardia 0 1 1
Other 1 0 1
COVID-19 14 6 20
Death§§§ 27 9 36
Dyspnea 4 1 5
Fall 1 6 7
Guillain-Barré syndrome 2 0 2
Hypertension, acute 7 3 10
Pericarditis¶¶¶ 1 3 4
Pneumonia 6 1 7
Seizure 6 0 6
Thrombotic event 20 11 31
Stroke or transient ischemic attack 12 5 17
Pulmonary embolism 5 5 10
Other 3 1 4
Chest pain, not otherwise specified 9 3 12
Myocardial infarction 5 3 8
Myocarditis**** 3 2 5
Abbreviations: MedDRA PT = Medical Dictionary for Regulatory Activities preferred term; VAERS = Vaccine Adverse Event Reporting System.
* Signs and symptoms in VAERS reports are assigned MedDRA PTs by VAERS staff members. Each VAERS report might be assigned more than one MedDRA PT,
which can include normal diagnostic findings. A MedDRA PT does not indicate a medically confirmed diagnosis.
† On August 31, 2022, the Food and Drug Administration authorized bivalent formulations of Moderna and Pfizer-BioNTech COVID-19 vaccines for use as a single
booster dose ≥2 months after completing primary or booster vaccination, Pfizer-BioNTech for persons aged ≥12 years and Moderna for adults aged ≥18 years.
§ One report was for a person who received both Moderna and Pfizer-BioNTech bivalent booster doses at the same visit and did not experience an adverse health event.
¶ Vaccine administration or handling errors.
** The most common MedDRA PTs among reports of vaccination error included incorrect product formulation administered, incorrect dose administered, underdose,
and wrong product administered.
†† Adverse health events coded for reports with nonserious vaccination errors included arthralgia, headache, injection site erythema, injection site swelling, fever,
pain, and pain in extremity.
§§ Excluding vaccination error MedDRA PTs.
¶¶ Includes the top 10 most frequently coded MedDRA PTs among nonserious reports.
*** VAERS reports are classified as serious if any of the following are reported: hospitalization, prolongation of hospitalization, life-threatening illness, permanent
disability, congenital anomaly or birth defect, or death. Serious reports to VAERS were reviewed by CDC physicians to form preliminary clinical impressions.
https://www.meddra.org/how-to-use/basics/hierarchy
††† Because of the small number of serious reports, percentages are not provided for serious report events. Other clinical impressions included acute pancreatitis, acute respiratory
failure, aneurysm, arm pain, arthralgia, aseptic meningitis, bilateral pleural effusion, cellulitis, chronic anemia, compression fracture, confusion, contact dermatitis, costochondritis,
erythema nodosum, fever, glaucoma, hearing loss, leukocytoplastic vasculitis, lower extremity weakness, lymphadenopathy, migraine, myalgia, pancreatitis, pericardial and
pleural effusions, pericardial tamponade, pylephlebitis, rhabdomyolysis, unspecified bradycardia, unspecified tachycardia, transverse myelitis, vertigo, and vision loss.
§§§ For reports of death, cause of death was available for four reports: cardiac arrest, dementia, metastatic prostate cancer, and myocardial infarction.
¶¶¶ All four reports of pericarditis have been verified by medical record review.
**** Three of the five reports of myocarditis have been verified by medical record review.

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US Department of Health and Human Services/Centers for Disease Control and Prevention
Summary
What is already known about this topic?
CDC recommended bivalent COVID-19 booster vaccination for
persons aged ≥12 years in August 2022; approximately
22.6 million bivalent booster doses were administered during
August 31–October 23, 2022.
What is added by this report?
Early safety findings from v-safe and the Vaccine Adverse Event
Reporting System for bivalent booster doses administered to
persons aged ≥12 years during the first 7 weeks of vaccine
availability are similar to those previously described for
monovalent vaccine booster vaccines.
What are the implications for public health practice?
Adverse events reported after a bivalent booster dose appear
consistent with those reported after a monovalent booster and
are less common and less serious than health impacts associ-
ated with COVID-19 illness.
Discussion
This report provides findings from v-safe and VAERS data
collected during the first 7 weeks of bivalent Pfizer-BioNTech
and Moderna mRNA booster dose administration among
persons aged ≥12 years, when 22.6 million booster doses were
administered in the United States. The findings in this report
are generally consistent with those from safety data from
preauthorization clinical trials of a BA.1 Omicron bivalent
booster vaccination.****,††††
Reporting frequencies of reactions and health impacts among
the 211,959 v-safe registrants aged ≥12 years who received
an age-appropriate bivalent booster vaccination are similar to
those described after receipt of first and second booster vac-
cine doses among adults aged ≥50 years (3–5). Among adults
aged ≥18 years, reporting frequencies of local and systemic
reactions after bivalent booster vaccination decreased with
increasing age. This reporting pattern was also observed for
primary series COVID-19 vaccination; v-safe registrants aged
≥65 years reported reactions less frequently after primary series
doses than did younger adults (6).
Most reports to VAERS for persons aged ≥12 years after
a bivalent booster dose were nonserious (95.5%) and were
usually similar to those after first booster vaccination and sec-
ond booster vaccination among adults aged ≥50 years (3–5).
Vaccination errors were among the most common events
reported to VAERS (34.5%); most (88.2%) of which did not
list an adverse health event. Continued education of vaccine
providers could help reduce administration errors.
**** https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2022-09-
01/07-COVID-Swanson-508.pdf
†††† https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2022-09-
01/06-covid-miller-508.pdf
Myocarditis and pericarditis are rare adverse events associ-
ated with receipt of COVID-19 mRNA vaccines (2). To date,
five reports of myocarditis and four reports of pericarditis after
bivalent booster vaccination were received by VAERS follow-
ing administration of 22.6 million doses among persons aged
≥12 years in the United States. Reporting rates of myocarditis
following COVID-19 mRNA primary series and monovalent
booster vaccination were highest among adolescent and young
adult males; myocarditis rates after monovalent booster dose
in these early data are similar to or lower than those after
primary series doses (2,7). In one study, an increased risk of
pericarditis was detected in the first week after the second dose
of COVID-19 mRNA vaccines among males aged 12–50 years
and females aged 30–50 years (8).
Among nonserious reports to VAERS were 258 (4.9%)
reports of COVID-19 disease; there were 20 (8.0%) serious
reports of COVID-19 disease. Vaccine effectiveness studies
have shown that among persons who were diagnosed with
COVID-19, previous vaccination with mRNA-based vac-
cines reduced COVID-19 disease severity, including the risk
of hospitalization and death (9,10).
The findings in this report are subject to at least three limita-
tions. First, v-safe is a voluntary program; therefore, data might
not be representative of the vaccinated population. Second, as
a passive surveillance system, VAERS is subject to reporting
biases and underreporting, especially of nonserious events (1).
Finally, conclusions drawn from these data are limited by the
7-week surveillance period; safety monitoring will continue
during the bivalent booster vaccination program.
As of October 12, 2022, ACIP recommends that all persons
aged ≥5 years receive an age-appropriate bivalent mRNA
booster dose ≥2 months after completion of a COVID-19
primary series or receipt of a monovalent booster dose (3).
Preliminary safety findings after bivalent booster vaccination
among persons aged ≥12 years are similar to those after mon-
ovalent booster vaccination (3–5). Health care providers and
patients can be reassured that adverse events reported after a
bivalent booster dose are consistent with those reported after
monovalent doses. Health impacts after COVID-19 vaccina-
tion are less frequent and less severe than those associated with
COVID-19 illness. CDC and FDA will continue to monitor
vaccine safety and will provide updates as needed to help guide
COVID-19 vaccination recommendations.
Acknowledgments
Charles Licata, Isaac McCullum, David Yankey.
Corresponding author: Anne M. Hause, voe5@cdc.gov.
1CDC COVID-19 Emergency Response Team; 2Food and Drug Administration,
Silver Spring, Maryland.

Morbidity and Mortality Weekly Report
1406 MMWR / November 4, 2022 / Vol. 71 / No. 44 US Department of Health and Human Services/Centers for Disease Control and Prevention
All authors have completed and submitted the International
Committee of Medical Journal Editors form for disclosure of potential
conflicts of interest. No potential conflicts of interest were disclosed.
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