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PLoS One. 2019 Aug 1;14(8):e0220453. doi: 10.1371/journal.pone.0220453. eCollection 2019.

Limited indirect effects of an infant pneumococcal vaccination program in an aging population.

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National Reference Center for Streptococci, Department of Medical Microbiology, University Hospital (RWTH), Aachen, Germany.



A general recommendation for adult pneumococcal vaccination with 23-valent polysaccharide vaccine (PPV23) for adults 60 and older has been in place in Germany since 1998, but uptake has been low. Just over a decade after the implementation of an infant pneumococcal conjugate vaccine recommendation, we examined indirect protection effects on adult invasive pneumococcal disease (IPD) in Germany.


Reported IPD cases decreased in children under two years of age from 11.09 per 100,000 in 2003-2006 to 5.94 per 100,000 in 2017/18, while in adult age groups, reported IPD cases rose across the board, most dramatically in adults 60 years of age and over, from 1.64 to 10.08 cases per 100,000. PCV13-type IPD represents 31% of all cases in this age group, the lion's share of which is due to the rapid increase of serotype 3 IPD, which, by itself, has reached 2.11 reported cases per 100,000 and makes up 21% of all IPD cases in this age group. The two vaccine formulations currently in development (PCV15 and PCV20) would increase current (PCV13) coverage by 8.5% points and 28.0% points in children, while in adults coverage would increase by 10.4% points and 21.9% points, respectively.


While original models predicted that indirect effects of childhood vaccination would suffice for adults, it seems that the herd protection effect has reached its limit, with vaccine serotypes 4, 19F, and 19A IPD persisting in adults after initial reductions, and serotype 3 IPD not showing any herd protection effect at all.

Conflict of interest statement

We have the following interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: Pneumococcal surveillance is funded in part by Pfizer Pharma GmbH. ML has received honoraria, travel grants, and served on advisory boards for Pfizer, GSK, MSD, and Sanofi Pasteur. MI has no competing interests. SP has received a travel grant from Pfizer. There are no patents, products in development or marketed products to declare. This does not alter our adherence to all the PLOS ONE policies on sharing data and materials.

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