The bivalent booster dose includes two different mRNA components of the SARS-COV-2 virus. One mRNA component is the original strain and the other is the BA.4 and BA.5 lineage of the omicron variant. The original strain, which is included in the monovalent primary series vaccine, is broadly protective. Whereas the omicron strain is included to provide protection against BA.4 and BA.5, which are more infectious and less susceptible to the original vaccine due to the mutation on the SARS-COV-2 spike protein.
In the past few weeks, new variants of concern have emerged: BQ.1, BQ.1.1, and XBB. As of December 3, 2022, BQ.1.1 (31.9%), BQ.1 (30.9%), and BA.5 (13.8%) are the most prominent variants whereas XBB (5.5%) is rapidly increasing, especially in the Northeast region of the United States. BQ.1.1 and XBB have additional mutations in the receptor binding domain of the spike protein, which is the major target for vaccines and monoclonal antibodies. Due to this, the efficacy of monoclonal antibodies (Regen-COV, EVUSHELD, bebtelovimab) have been minimized. Additionally, on November 30, 2022, FDA announced bebtelovimab is not currently authorized in any US region. Paxlovid, Veklury, and Lagevrio are all still authorized for use and are effective against the new variants.
For additional information or for clinical guidance, please see the sources below. The USET TEC is available to assist with any questions or concerns. Please do not hesitate to contact us at usetepi@usetinc.org.
Sources
FDA Authorizes Updated (Bivalent) COVID-19 Vaccines for Children Down to 6 Months of Age
CDC Clinical Guidance for COVID-19 Vaccines
CDC Special Situations for COVID-19 Vaccination of Children and Adolescents
CDC COVID Data Tracker Variant Proportions
Efficacy of Antiviral Agents against Omicron Subvariants BQ.1.1 and XBB
Anti-SARS-CoV-2 Monoclonal Antibodies
FDA Bebtelovimab
Not Currently Authorized in Any US Region
FDA Evusheld COVID-19 Risk for Certain Variants
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