CDC's Interim Bivalent COVID-19 Vaccine Recommendations, Spring 2023

This page records CDC's interim recommendations as of April 2023. They were explicitly interim and subject to change as evidence grew; for today's COVID-19 vaccine recommendations, see CDC's current guidance.

Throughout the COVID-19 public health emergency, CDC — guided by its Advisory Committee on Immunization Practices (ACIP) — issued vaccine recommendations after each Food and Drug Administration (FDA) action. Between August 2022 and April 2023, the FDA amended its Emergency Use Authorizations to allow a single, age-appropriate bivalent dose (containing equal parts of the original strain and Omicron BA.4/BA.5) for everyone aged 6 and older, bivalent doses for children aged 6 months to 5 years, and additional bivalent doses for immunocompromised people and adults 65 and older. Monovalent mRNA vaccines based on the original strain were no longer authorized after August 31, 2022. The vaccines available and recommended were the bivalent Pfizer-BioNTech and Moderna mRNA vaccines and the monovalent, protein subunit Novavax vaccine (for limited situations).

The evidence ACIP weighed

ACIP has met 35 times since June 2020, and its COVID-19 Vaccine Work Group met weekly. Using its Evidence to Recommendations framework, ACIP discussed bivalent vaccines at public meetings on September 1, 2022, February 24, 2023, and April 19, 2023.

• Protection wanes. For adults 18–64, vaccine effectiveness against emergency and urgent care visits fell from 53% at 7–59 days after a bivalent dose to 42% at 60–119 days; against hospitalization among those without immunocompromise, from 68% to 27%.
• Older adults carry the greatest burden. As of May 6, 2023, COVID-19 hospitalization rates were highest among adults 65 and older (9.5 per 100,000). Bivalent boosters gave adults the highest protection against hospitalization, sustained for at least 179 days against critical outcomes — yet only 17% of the population and 43.3% of adults 65 and older had received one.
• Immune response. A primary series of an Omicron BA.1-containing bivalent vaccine produced neutralizing titers against BA.1 about 25 times those from the original vaccine, with side effects similar to or fewer than the monovalent vaccine.
• Prior immunity is widespread. In 2022 studies, most children and adolescents (93% of those aged 5–17; 63% of infants aged 6–11 months) had evidence of past infection, and 96% of adult blood donors had immunity from infection, vaccination or both.
• Myocarditis. A rare risk of myocarditis and pericarditis, mainly in adolescent and young adult males, had been found after monovalent mRNA vaccines, and was higher with shorter intervals between doses. Data for bivalent doses were limited, but preliminary estimates suggested lower risk; one case of myopericarditis was seen in the Vaccine Safety Datalink within 7 days of a bivalent dose, in a man aged 18–29.
• Benefits of vaccination were seen in every age group and at every interval, largest among the oldest and those who had waited 11 months or longer since their primary series.

The recommendations

People 6 and older without moderate or severe immunocompromise (FDA authorized April 18; CDC recommended April 20, 2023): a single age-appropriate bivalent mRNA dose if unvaccinated; if previously vaccinated, one bivalent dose at least 2 months after their last monovalent dose.

Children 6 months to 5 years, by vaccination history:

• Ages 6 months–4 years: either mRNA vaccine, but all doses from the same manufacturer — at least 2 doses of Moderna, or at least 3 of Pfizer-BioNTech, including at least 1 bivalent dose.
• Age 5, unvaccinated: 2 doses of Moderna bivalent vaccine 4–8 weeks apart, or 1 dose of Pfizer-BioNTech.
• Age 5 with 1 or 2 monovalent Moderna doses: 1 dose of either bivalent vaccine; with 1 or more monovalent Pfizer-BioNTech doses: 1 or more bivalent Pfizer-BioNTech doses.

Studies supporting this showed bivalent doses broadened immune responses, and in 60 Pfizer-BioNTech trial participants aged 6 months–4 years, a bivalent dose after the primary series raised Omicron BA.4/BA.5 antibodies with fewer side effects than earlier monovalent doses and no new safety concerns.

Additional doses (FDA authorization April 2023):

• Adults 65 and older could choose 1 more bivalent dose at least 4 months after their last one. Their protection had waned: effectiveness against emergency and urgent care visits fell from 61% to 25%, and against hospitalization from 64% to 39%, between 7–59 and 120–179 days after vaccination.
• People 6 months and older with moderate or severe immunocompromise could choose 1 or more additional bivalent doses at least 2 months after the last, as clinical judgment, risk and personal circumstances indicated. For immunocompromised adults, effectiveness against hospitalization was 30% at 7–59 days and 31% at 120–179 days.

Simpler to deliver

Before these changes there were 11 licensed or authorized mRNA COVID-19 vaccine products; afterward there were five, and look-alike vials were eliminated — freeing storage space and potentially reducing administration errors. CDC advised that everyone 6 months and older stay up to date, including at least one bivalent dose, and that providers give recipients the EUA fact sheet and counsel them about expected side effects.

Reporting side effects

Adverse events after any COVID-19 vaccine should be reported to the Vaccine Adverse Event Reporting System (VAERS). Providers were required to report administration errors, serious adverse events, myocarditis, pericarditis, multisystem inflammatory syndrome, and COVID-19 cases resulting in hospitalization or death after vaccination under an EUA.

Sources

• Moulia DL, Wallace M, Roper LE, et al. "Interim Recommendations for Use of Bivalent mRNA COVID-19 Vaccines for Persons Aged ≥6 Months — United States, April 2023." MMWR 72(24). CDC.