The mRNA-1273 (Moderna) COVID-19 vaccine is a lipid nanoparticle-encapsulated,
nucleoside-modified mRNA vaccine encoding the stabilized prefusion spike glycoprotein
of
SARS-CoV-2, the virus that causes COVID-19. During December 2020, the vaccine was
granted Emergency Use Authorization (EUA) by the Food and Drug Administration (FDA),
and
the Advisory Committee on Immunization Practices (ACIP) issued an interim recommendation
for use among persons aged ≥18 years (
1
), which was adopted by CDC. During December 19,
2020–January 30, 2022, approximately 204 million doses of Moderna COVID-19
vaccine were administered in the United States (
2
) as a primary series of 2 intramuscular doses (100
μg [0.5 mL] each) 4 weeks apart. On January 31, 2022, FDA
approved a Biologics License Application (BLA) for use of the Moderna COVID-19 vaccine
(Spikevax, ModernaTX, Inc.) in persons aged ≥18 years (
3
). On February 4, 2022, the ACIP COVID-19 Vaccines
Work Group conclusions regarding recommendations for the use of the Moderna COVID-19
vaccine were presented to ACIP at a public meeting. The Work Group’s
deliberations were based on the Evidence to Recommendation (EtR) Framework,* which
incorporates the Grading of Recommendations,
Assessment, Development and Evaluation (GRADE) approach
†
to rank evidence quality. In addition to initial
clinical trial data, ACIP considered new information gathered in the 12 months since
issuance of the interim recommendations, including additional follow-up time in the
clinical trial, real-world vaccine effectiveness studies, and postauthorization vaccine
safety monitoring. ACIP also considered comparisons of mRNA vaccine effectiveness
and
safety in real-world settings when first doses were administered 8 weeks apart instead
of the original intervals used in clinical trials (3 weeks for BNT162b2
[Pfizer-BioNTech] COVID-19 vaccine and 4 weeks for Moderna COVID-19 vaccine). Based
on
this evidence, CDC has provided guidance that an 8-week interval might be optimal
for
some adolescents and adults. The additional information gathered since the issuance
of
the interim recommendations increased certainty that the benefits of preventing
symptomatic and asymptomatic SARS-CoV-2 infection, hospitalization, and death outweigh
vaccine-associated risks of the Moderna COVID-19 vaccine. On February 4, 2022, ACIP
modified its interim recommendation to a standard recommendation
§
for use of the fully licensed Moderna COVID-19
vaccine in persons aged ≥18 years.
Recommendations for Use of Moderna COVID-19 Vaccine
During June 2020–February 2022, ACIP convened 23 public meetings to review
data on the epidemiology of COVID-19 and considerations for use of all COVID-19
vaccines, including the Moderna COVID-19 vaccine (
4
). The ACIP COVID-19 Vaccines Work Group, which
includes experts in infectious diseases, vaccinology, vaccine safety, public health,
and ethics, held meetings each week to review COVID-19 epidemiologic and
surveillance data on vaccine efficacy, effectiveness, and safety and implementation
considerations. After a systematic review of published and unpublished scientific
evidence for benefits and harms
¶
of Moderna COVID-19 vaccination, the Work Group used
a modified GRADE approach to assess the certainty of evidence for outcomes related
to the vaccine, rated on a scale of type 1 to type 4 (type 1 = high
certainty, type 2 = moderate certainty, type 3 = low
certainty, and type 4 = very low certainty). Within the EtR Framework,
ACIP considered the importance of COVID-19 as a public health problem, benefits and
harms (as informed by the GRADE evidence assessment), patients’ values and
preferences, issues of resource use, acceptability to stakeholders, feasibility of
implementation, and anticipated impact on health equity. Work Group conclusions
regarding the evidence for the Moderna COVID-19 vaccine were presented to ACIP at
a
public meeting on February 4, 2022.**
The body of scientific evidence for potential benefits and harms of the Moderna
COVID-19 vaccine was guided by one large randomized, double-blind,
placebo-controlled Phase III clinical trial (
5
,
6
), one Phase II clinical trial (
7
), one small Phase I clinical trial (
8
,
9
), 26 observational vaccine effectiveness
studies, and two postauthorization vaccine safety monitoring systems: the Vaccine
Adverse Events Reporting System (VAERS) and the Vaccine Safety Datalink (VSD). VAERS
is a national passive surveillance vaccine safety monitoring system managed by CDC
and FDA. VSD covers nine participating integrated health care organizations serving
approximately 12 million persons and identifies possible adverse events after
vaccination, using detailed clinical and demographic data available in near real
time from electronic medical records. Updated findings from the ongoing Phase III
clinical trial were based on 30,420 enrolled participants contributing approximately
11,000 person-years of data, with a median follow-up of 5 months during September
4,
2020–March 26, 2021 (ending with the date placebo recipients were offered
crossover to receive study vaccine). Pooled effectiveness estimates were calculated
when multiple observational studies reported data on a specific outcome; the study
periods for the observational studies included in the pooled estimates ranged from
1
to 10 months (median = 5 months).
The estimated efficacy of the Moderna COVID-19 vaccine in the Phase III clinical
trial was based on outcomes that occurred ≥14 days after receipt of the
second dose. The demographic characteristics of participants, including age and race
(
5
), have remained
consistent since initial enrollment. Efficacy in preventing symptomatic,
laboratory-confirmed COVID-19 in persons aged ≥18 years without evidence of
previous SARS-CoV-2 infection was 92.7% (Table
1). One hospitalization occurred among the vaccinated group and 24
hospitalizations among the placebo group, yielding an estimated vaccine efficacy of
95.9% against COVID-19–associated hospitalization. No
COVID-19–associated deaths occurred among study participants in the
vaccinated group, and three occurred in the placebo group resulting in a vaccine
efficacy of 100% against COVID-19–associated deaths. Efficacy in preventing
asymptomatic SARS-CoV-2 infection was 57.4%. Observational data were available for
all beneficial outcomes assessed: the pooled vaccine effectiveness estimates were
89.2% for prevention of symptomatic, laboratory-confirmed COVID-19 (11 studies);
94.8% against COVID-19–associated hospitalizations (15 studies), 93.8%
against COVID-19–associated death (five studies), and 69.8% against
asymptomatic SARS-CoV-2 infection (three studies). Most of the follow-up time
occurred before B.1.1.529 (Omicron) became the predominant circulating SARS-CoV-2
variant. From the GRADE evidence assessment, the level of certainty for the benefits
of Moderna COVID-19 vaccination among persons aged ≥18 years was type 1 (high
certainty) for the prevention of symptomatic SARS-CoV-2 infection, type 1 (high
certainty) for the prevention of asymptomatic SARS-CoV-2 infection, type 2 (moderate
certainty) for prevention of COVID-19–associated hospitalization, and type 2
(moderate certainty) for the prevention of COVID-19–associated death.
TABLE 1
Summary of the certainty of evidence of potential benefits of Moderna
COVID-19 vaccination — United States, February 2022
Potential
benefit
Clinical
trial evidence
Observational evidence
GRADE
evidence certainty†
No. of
studies
Vaccine efficacy (95%
CI)
No. of studies
Pooled vaccine
effectiveness* (95% CI)
Prevention of symptomatic,
laboratory-confirmed COVID-19§
1
92.7 (90.4–94.4)
11
89.2 (82.0–93.6)
1
Prevention of
COVID-19–associated
hospitalization§
1
95.9 (69.5–99.4)
15
94.8 (93.1–96.1)
2
Prevention of
COVID-19–associated death
1
100 (NE–100)
5
93.8 (91.5–95.4)
2
Prevention of asymptomatic
SARS-CoV-2 infection
1
57.4 (50.1–63.6)
3
69.8 (60.9–76.7)
1
Abbreviations: GRADE = Grading of Recommendations,
Assessment, Development and Evaluation; NE = not
evaluable.
* Vaccine effectiveness estimates were pooled to provide an overall estimate
across studies for the purposes of GRADE review.
† GRADE evidence certainty: 1 = high
certainty, 2 = moderate certainty, 3 = low
certainty, 4 = very low certainty.
§ Considered a critical outcome in GRADE. https://www.cdc.gov/vaccines/acip/recs/grade/about-grade.html
In the Phase III clinical trial, severe local and systemic adverse reactions (i.e.,
reactogenicity) in the 7 days after vaccination (grade 3 or higher,
††
defined as adverse
reactions interfering with daily activity) were more likely to occur among vaccine
recipients (21.3%) than placebo recipients (4.5%) (relative risk = 5.03; 95%
CI = 4.65–5.45) (Table
2). Among vaccine recipients, the most common grade 3 symptoms were fatigue,
headache, joint pain, muscle pain, and injection-site pain. Overall, reactions
categorized as grade 3 or higher were more likely to be reported after the second
dose than after the first dose. The frequency of serious adverse events
§§
was 1.7% among
vaccine recipients and 1.9% among placebo recipients. Based on data from VAERS and
VSD, two rare but clinically serious adverse events after vaccination were detected:
anaphylaxis and myocarditis or myopericarditis.
¶¶
Based on VSD data, 5.1 cases of
anaphylaxis per 1 million doses of Moderna COVID-19 vaccine administered among
persons aged ≥18 years were observed (
10
). Myocarditis or pericarditis were more common
among vaccine recipients who were younger and male, and occurred more frequently
after the second vaccine dose; 65.7 cases per 1 million doses of Moderna COVID-19
vaccine administered were observed from analysis of VSD chart-reviewed myocarditis
and myopericarditis cases that met CDC case definitions (
11
) among men aged 18–39 years after
dose 2 and occurring within a 0–7-day risk interval after vaccination.
Although VAERS data are subject to the limitations of a passive surveillance
system,*** the elevated number of observed
versus expected myocarditis and myopericarditis cases during the 0–7-day risk
interval after receipt of the second Moderna vaccine dose is generally consistent
with the findings from VSD. The level of certainty from the GRADE evidence
assessment regarding potential harms after vaccination was type 2 (moderate
certainty) for serious adverse events and type 1 (high certainty) for
reactogenicity. GRADE was last completed for Moderna COVID-19 primary vaccination
in
December 2020 (
1
); since that
time, additional data became available on all prespecified outcomes of interest,
resulting in a higher level of certainty in the estimates for the benefit of
vaccination in prevention of asymptomatic infection and death (the GRADE evidence
profile is available at https://www.cdc.gov/vaccines/acip/recs/grade/bla-covid-19-moderna-vaccine.html).
Overall, the benefits for the Moderna COVID-19 vaccine outweigh any observed
vaccine-associated risks (Table 1) (Table 2).
TABLE 2
Summary of the certainty of evidence of potential harms of Moderna
COVID-19 vaccination — United States, February 2022
Characteristic
Clinical
trial evidence
Observational evidence
GRADE
evidence certainty*
No. of
studies
Relative risk (95%
CI)
No. of studies
No. of cases per 1
million doses
Potential
harms, pooled data
Reactogenicity
2
5.03 (4.65–5.45)
0
—
†
1
Serious adverse
events§
2
0.92 (0.78–1.08)
0
—¶
2
Potential
harms by data source
VSD
Anaphylaxis, persons
≥18 yrs
NA
NA
1
5.1**
3
Myocarditis,
sex and age group, yrs
Men, 18–39
NA
NA
1
65.7††
3
Women, 18–39
NA
NA
1
6.2††
3
VAERS
Myocarditis,
sex and age group, yrs
Men, 18–24
NA
NA
1
40.0§§
3
Women, 18–24
NA
NA
1
5.5§§
Men, 25–29
NA
NA
1
18.3¶¶
Women, 25–29
NA
NA
1
5.8¶¶
Men, 30–39
NA
NA
1
8.4***
Women, 30–39
NA
NA
1
0.6***
Abbreviations: GRADE = Grading of Recommendations,
Assessment, Development and Evaluation; NA = not applicable;
RR = relative risk; VAERS = Vaccine Adverse Event Reporting
System; VSD = Vaccine Safety Datalink.
* GRADE evidence certainty is ranked as follows: 1 = high
certainty, 2 = moderate certainty, 3 = low
certainty, 4 = very low certainty.
† Observational evidence did not include a measure of
reactogenicity.
§ Considered a critical outcome in GRADE. https://www.cdc.gov/vaccines/acip/recs/grade/about-grade.html
¶ Observational evidence did not include an aggregate
measure of serious adverse events. Data on specific serious adverse events
identified through postauthorization safety surveillance were reviewed.
Increased risk for myocarditis and anaphylaxis were observed in VAERS and
VSD.
** Based on VSD chart reviewed cases of anaphylaxis, in persons aged
≥18 years, occurring in a 0–1-day risk interval after
vaccination (RR = 5.1; 95%
CI = 3.3–7.6).
†† Based on VSD chart-reviewed cases of myocarditis
and pericarditis that met CDC case definitions among persons aged
18–39 years after dose 2, occurring in a 0–7-day risk interval
after vaccination.
§§ Based on VAERS chart-reviewed cases of
myocarditis that met CDC case definitions among men and women aged
18–24 years, days 0–7 after dose 2.
¶¶ Based on VAERS chart-reviewed cases of
myocarditis that met CDC case definitions among men and women aged
25–29 years, days 0–7 after dose 2.
*** Based on VAERS chart-reviewed cases of myocarditis that met CDC case
definitions among men and women aged 30–39 years, days 0–7
after dose 2.
Data reviewed within the EtR Framework support the use of the Moderna COVID-19
vaccine. The Work Group concluded that COVID-19 remains an important public health
problem and that the desirable effects of disease prevention through vaccination
with Moderna COVID-19 vaccine in persons aged ≥18 years are large and
outweigh the potential harms. With 204 million doses of Moderna COVID-19 vaccine
administered to date (
2
), the
Work Group determined that the vaccine is acceptable to vaccine providers and that
implementation of vaccination is feasible. The Work Group also acknowledged that
vaccine-eligible persons aged ≥18 years probably considered the desirable
effects of vaccination to be favorable compared with the undesirable effects;
however, there is likely important variability in vaccine acceptance within this age
group, especially among those who are currently unvaccinated. Despite having
recommendations for the Moderna COVID-19 vaccine for >1 year, data indicate
vaccine coverage varies by geography, race/ethnicity, sexual orientation, and gender
identity (
12
–
14
). Because these disparities
remained even after the Pfizer COVID-19 vaccine had received standard authorization,
the Work Group concluded that changing from an interim to a standard ACIP
recommendation alone for the Moderna COVID-19 vaccine would probably have minimal
impact on health equity (the evidence used to inform the EtR is available at
https://www.cdc.gov/vaccines/acip/recs/grade/bla-covid-19-moderna-etr.html).
Interval Between Primary mRNA COVID-19 Vaccination Series Doses
In addition to data presented to guide the recommendation for use of the Moderna
COVID-19 vaccine, data were also presented to ACIP regarding the optimal interval
between the first and second dose of a Moderna or Pfizer-BioNTech mRNA primary
vaccination series. mRNA COVID-19 vaccines are safe and effective at the authorized
interval between the first and second doses (4 weeks for Moderna vaccine; 3 weeks
for Pfizer-BioNTech vaccine), but an extended interval might be considered for some
populations. An elevated risk for myocarditis and myopericarditis among mRNA
COVID-19 vaccine recipients has been observed, particularly in adolescent and young
adult males (
11
,
15
). Several studies in
adolescents and adults have indicated the small risk for myocarditis associated with
mRNA COVID-19 vaccines might be reduced (
16
) and peak antibody responses and vaccine
effectiveness might be increased (
17
–
20
) with an interval longer than 4 weeks between
the 2 primary series doses. In a population-based cohort study in Ontario, Canada,
rates of myocarditis among persons aged ≥18 years were lower with an extended
interval (>4 to <8 weeks and ≥8 weeks) compared with the shorter
interval (3–4 weeks) between the first and second doses of a primary series
for both Moderna and Pfizer-BioNTech vaccines (
16
). In several studies, neutralizing antibody
titers were higher after an extended interval between doses in a primary mRNA
vaccine series (range = 6–14 weeks), compared with a standard
interval of 3–4 weeks (
17
–
20
). Vaccine effectiveness against infection and
hospitalization was higher with an extended (6–8-week) interval than with a
standard (3–4-week) interval (
19
).
†††
Based on this evidence presented
to ACIP, CDC has provided guidance that an 8-week interval might be optimal for some
adolescents and adults, especially for males aged 12–39 years. Additional
primary series interval considerations are available at https://www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html.
After a year of use under an FDA-issued EUA and ACIP interim recommendation, the
Moderna COVID-19 vaccine received full FDA approval and is recommended by ACIP for
use in persons aged ≥18 years in the United States. Spikevax, the trade name
of the Moderna COVID-19 vaccine, has the same formulation and can be used
interchangeably with the Moderna COVID-19 vaccine used under EUA without presenting
any safety or effectiveness concerns. ACIP considered new information beyond what
was available at the time of the interim recommendation, including an additional 3
months of follow-up of the Phase III clinical trial participants, 26 observational
vaccine effectiveness studies involving large populations of vaccinated persons, and
two postauthorization safety monitoring systems with data from millions of
vaccinated persons in the United States. The additional information increased
certainty that the benefits of Moderna COVID-19 vaccine outweigh vaccine-associated
risks. The Moderna COVID-19 vaccine continues to have FDA authorization and interim
ACIP recommendations for a booster dose (
21
), as well as an additional dose in persons aged
≥18 years with moderate to severe immunocompromise (
22
). For an mRNA primary series, an 8-week
interval between first and second doses might be optimal for some persons aged
≥12 years, especially males aged 12–39 years.
Before vaccination, a fact sheet (
23
) or vaccine information sheet should be provided to
recipients. Providers should counsel Moderna COVID-19 vaccine recipients about
expected systemic and local reactogenicity. Additional clinical considerations for
COVID-19 vaccine administration are available at https://www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html
Reporting of Vaccine Adverse Events
Providers are required to report adverse events that occur after receipt of any
COVID-19 vaccine to VAERS (
23
) (https://vaers.hhs.gov/index.html or
1–800–822–7967). Any person who administers or receives a
COVID-19 vaccine is encouraged to report any clinically significant adverse event,
regardless of whether it is clear that a vaccine caused the adverse event. In
addition, all COVID-19 vaccine recipients are encouraged to enroll in v-safe, a CDC
voluntary smartphone-based online tool that uses text messaging and online surveys
to conduct periodic health check-ins after vaccination. CDC’s v-safe
(https://www.cdc.gov/vsafe
) call center
follows up on reports to v-safe that include possible medically significant health
events to collect additional information for completion of a VAERS report.
Summary
What is already known about this topic?
On January 31, 2022, the Food and Drug Administration (FDA) granted full
approval to the Moderna COVID-19 vaccine for persons aged ≥18
years.
What is added by this report?
On February 4, 2022, after a systematic review of the evidence, the
Advisory Committee on Immunization Practices issued a standard
recommendation for use of the Moderna COVID-19 vaccine in persons
aged ≥18 years. CDC provided guidance that an 8-week interval between
primary series doses of mRNA vaccines might be optimal for some persons.
What are the implications for public health practice?
Use of the FDA-approved Moderna COVID-19 vaccine is recommended for persons
aged ≥18 years; benefits of the prevention of infection and
associated hospitalization or death outweigh vaccine-associated risks.