The U.S. Food and Drug Administration’s (FDA) Vaccines and Related Biologics Advisory Committee (VRBPAC) voted unanimously to support the next formulation change for COVID-19 vaccines to be a monovalent XBB strain at their June meeting. The original strain no longer protects as well against severe disease. Early results show monovalent XBB vaccines provide a better immune response compared to various bivalent formulations. The XBB strain vaccine seems to provide better cross-protection against other strains within the Omicron lineage even though it is not specifically matched to those strains.  

Based on data presented by CDC and vaccine manufacturers, the committee supports a formulation change to the XBB.1.5 strain. The FDA and manufacturers predict availability by September through licensure or emergency use authorization. 

For more details, including meeting materials, refer to Vaccines and Related Biological Products Advisory Committee June 15, 2023 Meeting Announcement (https://www.fda.gov/advisory-committees/advisory-committee-calendar/vaccines-and-related-biological-products-advisory-committee-june-15-2023-meeting-announcement)  

On June 23, CDC’s Advisory Committee on Immunization Practices (ACIP) met to discuss COVID-19 vaccine topics including epidemiology, effectiveness, dose simplification for children, and hybrid immunity. The committee reviewed the Epidemiology of COVID-19-Associated Hospitalization, Including in Pregnant Persons and Infants (https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2023-06-21-23/02-COVID-Havers-Galang-Link-Gelles-508.pdf). The highest rates of hospitalization currently occur in adults over 75 years of age, followed by infants less than 6 months and adults 65-74 years. COVID-19 vaccination improves outcomes for pregnant people, their pregnancies, and their infants. Therefore, vaccination continues to be recommended for maternal and fetal benefit.   

Bivalent vaccines continue to provide additional protection against hospitalization, though there is evidence of waning. Effectiveness against the most critical illness is more sustained compared to less severe illness. The work group suggested that a single dose of a COVID-19 vaccine may be reasonable for possible future recommendations for 2–4-year-olds, instead of a multidose series. Previously infected people are encouraged to get vaccinate as hybrid immunity (vaccination plus natural infection) may protect better against infection and severe disease with Omicron compared to protection from infection or vaccination alone. Current protection is influenced by the cumulative number of vaccine doses, number of times infected, and timing of most recent vaccination or infection, and how closely the circulating variant matches the vaccine or prior infection.   

Details including the agenda and slides can be found at CDC | Advisory Committee on Immunization Practices (ACIP) (https://www.cdc.gov/vaccines/acip/index.html)