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. 2019 Jan 9;9(1):6.
doi: 10.1038/s41598-018-36799-x.

Dominance of vaccine serotypes in pediatric invasive pneumococcal infections in Portugal (2012-2015)

Catarina Silva-Costa  1 , Maria J Brito  2 , Sandra I Aguiar  1 , Joana P Lopes  1 , Mário Ramirez  3 , José Melo-Cristino  1 ; Portuguese Group for the Study of Streptococcal Infections; Portuguese Study Group of Invasive Pneumococcal Disease of the Pediatric Infectious Disease Society
Collaborators, Affiliations

Dominance of vaccine serotypes in pediatric invasive pneumococcal infections in Portugal (2012-2015)

Catarina Silva-Costa et al. Sci Rep. .

Abstract

We evaluated the impact of continued 13-valent pneumococcal conjugate vaccine (PCV13) use in the private market (uptake of 61%) in pediatric invasive pneumococcal disease (pIPD) in Portugal (2012-2015). The most frequently detected serotypes were: 3 (n = 32, 13.8%), 14 (n = 23, 9.9%), 1 (n = 23, 9.9%), 7F (n = 15, 6.4%), 19A (n = 13, 5.6%), 6B and 15B/C (both n = 12, 5.2%), and 24F, 10A and 12B (all with n = 10, 4.3%). Taken together, non-PCV13 serotypes were responsible for 42.2% of pIPD with a known serotype. The use of PCR to detect and serotype pneumococci in both pleural and cerebrospinal fluid samples contributed to 18.1% (n = 47) of all pIPD. Serotype 3 was mostly detected by PCR (n = 21/32, 65.6%) and resulted from a relevant number of vaccine failures. The incidence of pIPD varied in the different age groups but without a clear trend. There were no obvious declines of the incidence of pIPD due to serotypes included in any of the PCVs, and PCV13 serotypes still accounted for the majority of pIPD (57.8%). Our study indicates that a higher vaccination uptake may be necessary to realize the full benefits of PCVs, even after 15 years of moderate use, and highlights the importance of using molecular methods in pIPD surveillance, since these can lead to substantially increased case ascertainment and identification of particular serotypes as causes of pIPD.

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Conflict of interest statement

J.M.C. has received research grants administered through his university and received honoraria for serving on the speakers bureaus of Pfizer and Merck Sharp and Dohme. M.R. has received honoraria for serving on the speakers bureau of Pfizer and for consulting for GlaxoSmithKline and Merck Sharp and Dohme. The other authors declare no conflict of interest. No company or financing body had any interference in the decision to publish.

Figures

Figure 1
Figure 1
Incidence of invasive pneumococcal disease in children and adolescents in Portugal (2012–2013 to 2014–2015). The 95% confidence intervals for the incidence estimates are indicated.
Figure 2
Figure 2
Number of samples representing serotypes present in conjugate vaccines causing invasive infections in Portugal (2012–2013 to 2014–2015). The number of samples representing each serotype in each of the age groups considered is indicated. Isolates presenting both erythromycin resistance and penicillin non-susceptibility (EPNSP) are represented by red bars. Penicillin non-susceptible isolates (PNSP) are indicated by orange bars. Erythromycin resistant isolates (ERSP) are indicated by yellow bars. Isolates susceptible to both penicillin and erythromycin are represented by green bars. Cases where no sample was available or where pneumococci were detected exclusively by PCR and for which susceptibility is unknown, are indicated by white bars. The serotypes included in each of the conjugate vaccines are indicated by the arrows. NVT – non-vaccine serotypes, i.e., serotypes not included in any of the currently available conjugate vaccines (PCV7, PCV10 and PCV13). The values indicated below the arrows are the proportion of each group in the overall cases (n = 259).
Figure 3
Figure 3
Number of samples representing serotypes not present in conjugate vaccines causing invasive infections in Portugal (2012–2013 to 2014–2015). See the legend of Fig. 2. NT – Non-typeable. Some serotypes could not be unambiguously determined and are indicates as such (see text). Among the 12 isolates identified as 15B/C, 8 were originally typed as 15B and 4 isolates were typed as 15C.
Figure 4
Figure 4
Incidence of invasive pneumococcal disease in children and adolescents in Portugal (2011–2012 to 2014–2015). NVT – non-vaccine serotypes.
See this image and copyright information in PMC

References

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