Pneumococcal polysaccharide 23-valent vaccine: long-term persistence of circulating antibody and immunogenicity and safety after revaccination in adults

Since publication of a 1997 review of the immunogenicity and safety data for pneumococcal polysaccharide vaccines (PPSVs), dozens of additional studies have been published, involving larger cohorts, longer observation periods, and more specific assays. Additionally, a 13-valent pneumococcal conjugate vaccine (PCV) has been licensed for adults. This paper reviews adult studies assessing antibody persistence for ≥ 3 years after pneumococcal vaccination, and adult studies of immunogenicity and safety after revaccination. This review emphasizes the currently registered PPSV23 formulations containing 25-μg polysaccharide per serotype, for which far more long-term data are available. Broadly, IgG and functional antibody levels after PPSV23 in adults persist above concentrations in unvaccinated adults for at least 5-10 years in most studies. The few exceptions involve populations of non-ambulatory adults or those with confounding host-factor issues. Revaccination with PPSV23 5-10 years after a previous dose consistently and substantially increases both IgG and functional antibody levels. There is an inverse association between circulating antibody level just before primary or revaccination and subsequent antibody increase. Although injection-site reactions (e.g., pain, swelling, redness) were reported more commonly after PPSV23 revaccination than after primary vaccination in most studies, these reactions typically resolved within 5 days. We interpret the contemporary literature as supporting pneumococcal revaccination as a means to sustain anti-pneumococcal antibodies at levels greater than among unvaccinated adults. PPSV23 is a broad-spectrum public-health tool to help prevent serious pneumococcal diseases across the adult lifespan.