Boosting with the New Bivalent COVID-19 Vaccines
By Stan Deresinski, MD, FACP, FIDSA
Clinical Professor of Medicine, Stanford University
SYNOPSIS: The Centers for Disease Control and Prevention has made recommendations for the use of the newly approved bivalent COVID-19 booster vaccine.
SOURCE: Oliver S. Evidence to recommendations framework: Bivalent COVID-19 vaccine booster doses. ACIP Meeting. Sept. 1, 2022. https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2022-09-01/08-COVID-Oliver-508.pdf
On Sept. 1, 2022, the Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practice (ACIP) recommended the use of two new bivalent COVID-19 booster vaccines. The vaccines are designed to elicit an antibody response to the currently circulating (in the United States) Omicron subvariants as well as to “ancestral” virus.
The Moderna bivalent COVID-19 vaccine contains 25 mcg of spike protein from the original SARS-CoV-2 and 25 mcg from Omicron (BA.4/BA.5) SARS-CoV-2. The total amount of spike protein in each is identical to the amount of “ancestral” spike protein in the original products. Both the Moderna bivalent vaccine and Pfizer-BioNTech bivalent vaccine appear to be safe (although there are inadequate data to assess the risk of myocarditis/pericarditis) and, while as yet there are no data evaluating clinical efficacy (and some modeling suggests this may not be of great magnitude), each was superior to boosting with the original vaccines in elevating neutralizing antibody levels against Omicron and was non-inferior in boosting the response to the ancestral strain.1
APIC voted to recommend a single dose of one of the bivalent vaccines at least two months after receipt of a primary series or booster of monovalent vaccine. The Pfizer-BioNTech bivalent vaccine is recommended for individuals ≥ 12 years of age while Moderna’s is for those ≥ 18 years old. Monovalent vaccine will no longer be used for boosting.
Prior COVID-19 infection provides incomplete protection against reinfection and infection with the currently circulating SARS-CoV-2 variants. A Working Group evaluation concluded that individuals with recent SARS-CoV-2 infection “may consider delaying a vaccine dose by three months from onset or positive test.”
COMMENTARY
The original COVID-19 vaccines have been very effective, but viral evolution and waning levels of immunity, along with evidence of frequent reinfection after initial Omicron infection, dictate the need for an effective booster vaccine. The new booster vaccines contain viral spike protein from the BA.4 and BA.5 subvariants of the Omicron variant as well as ancestral spike protein. This results in elicitation of higher levels and broader specificities of neutralizing antibody. Experience in > 1,400 recipients indicates apparent safety, although low frequency signals, such as the potential occurrence of myopericarditis/pericarditis, will require ongoing adverse event surveillance.
In summary of current recommendations, having met age requirements, eligibility for bivalent booster vaccine receipt requires that individuals must have completed their primary vaccine series at least two months prior to boosting. The number of previous monovalent booster vaccine doses (including none) is irrelevant. Monovalent vaccine will no longer be used for boosting.
A bivalent booster dose may be given after a recent episode of COVID-19 infection, but consideration should be given to delaying its administration for at least three months, although this recommendation is not yet firm.
REFERENCE
- Callaway E. New Omicron-specific vaccines offer similar protection to existing boosters. Nature 2022;609:232-233.
The Centers for Disease Control and Prevention has made recommendations for the use of the newly approved bivalent COVID-19 booster vaccine.
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