Abstract:
The introduction of pneumococcal conjugate vaccines (PCVs) 7 and 13 into
national childhood immunization programs in the US in 2000 and 2010,
respectively, proved to be remarkably successful in reducing infant
mortality due to invasive pneumococcal disease (IPD), resulting in
widespread uptake of these vaccines. Secondary herd protection of
non-vaccinated adults against IPD has proven to be an additional public
health benefit of childhood immunization with PCVs, particularly in the case
of the vulnerable elderly who are at increased risk due to
immunosenescence and underlying comorbidity. Despite these advances
in pneumococcal immunization, the global burden of pneumococcal
disease, albeit of unequal geographic distribution, remains high. Reasons
for this include restricted access of children living in many developing
countries to PCVs, the emergence of infection due to non-vaccine
serotypes of the pneumococcus, and non-encapsulated strains of the
pathogen. Emerging concerns affecting the elderly include the realization
that herd protection conferred by the current generation of PCVs (PCV7,
PCV10, and PCV13) has reached a ceiling in many countries at a time of
global population aging, compounded by uncertainty surrounding those
immunization strategies that induce optimum immunogenicity and
protection against IPD in the elderly. All of the aforementioned issues,
together with a consideration of pipeline and pending strategies to improve
access to, and serotype coverage of, PCVs, are the focus areas of this
review.
