The Advisory Committee on Immunization Practices (ACIP) issued its new pneumococcal vaccine recommendations, made necessary by the FDA approval in 2021 of 2 new conjugate pneumoccal vaccines: Prevnar 20™ (PCV20) and Vaxneuvance™ (PCV15). The first protects against 20 pneumoccal strains, the second against 15.
The approval was based on studies that compared antibody responses to PCV20 and PCV15 with those to Prevnar 13® (PCV13), which is still used in persons aged ≤18 years but no longer recommended for adults. The approvals offered an opportunity to review ACIP’s existing recommendations and available data on the current pneumococcal vaccines. Pneumovax® (PPSV23) protects against 23 strains, but is a polysaccharide vaccine and does not stimulate memory B cells like the conjugate vaccines. Antibody studies done in older adults with PPSV23 show a decline in levels to pre-vaccine levels in 4 to 7 years. Observational studies of clinical effectiveness generally suggest a decline of effectiveness with time since administration, which is what would be expected with a polysaccharide vaccine. Prevnar 20 is currently in phase 3 trials for use in children.
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