Initial Effects of the National PCV7 Childhood Immunization Program on Adult Invasive Pneumococcal Disease in Israel

Gili Regev-Yochay,Jacob Strahilevitz,Galia Rahav,Gabriel Weber,Michal Stein,Yonit Wiener-Well,Klaris Riesenberg,Ron Dagan,Daniel Glikman,Israel Potasman,Sanjai Kumar

doi:10.1371/journal.pone.0088406

Abstract

BackgroundPCV7 was introduced as universal childhood vaccination in Israel in July 2009 and PCV13 in November 2010. Here we report data on adult invasive pneumococcal disease (IPD), two years post PCV7 implementation and before an expected effect of PCV13.MethodsAn ongoing nationwide active-surveillance (all 27 laboratories performing blood cultures in Israel), providing all blood & CSF S. pneumoniae isolates from persons >18 y was initiated in July 2009. Capture-recapture method assured reporting of >95% cases. All isolates were serotyped in one central laboratory. IPD outcome and medical history were recorded in 90%. Second year post PCV implementation is compared to the first year.ResultsDuring July 2009 to June 2011, 970 IPD cases were reported (annual incidence [/100,000] of 9.17 and 10.16 in the two consecutive years, respectively). Respective case fatality rates (CFRs) were 20% and 19.1%. Incidence of IPD and CFR increased with age and number of comorbidities. Incidence rate was significantly greater during the second winter, 7.79/100,000 vs. 6.14/100,000 in first winter, p = 0.004, with a non-significant decrease during summer months (3.02 to 2.48/100,000). The proportion of IPD cases due to PCV7-serotypes decreased from 27.5% to 13.1% (first to second year) (p<0.001). Yet, non-PCV13-strains increased from 32.7% to 40.2% (p = 0.017). The increase in non-PCV13-strains was highly significant in immunocompromised patients and to a lesser degree in non-immunocompromised at risk or in older patients (>64 y). Among younger/healthier patients serotype 5 was the major increasing serotype. Penicillin and ceftriaxone resistance decreased significantly in the second year.ConclusionsWhile overall annual incidence of IPD did not change, the indirect effect of PCV7 vaccination was evident by the significant decrease in PCV7 serotypes across all age groups. Increase in non-VT13 strains was significant in immunocompromised patients. A longer follow-up is required to appreciate the full effect of infant vaccination on annual IPD.

Highlights

Pneumococcal infections, including invasive pneumococcal diseases (IPD), such as bacteremia and meningitis, cause a significant morbidity and mortality in adults [1]
In some countries increases in nonvaccine type (NVT) strains causing infection largely offset the reduction in PCV7 vaccine serotypes (VT7) [5,7,10,11,12]
From July 2009, until July 2011, 970 IPD cases were reported in adults; 460 during 2009–10 and 520 during 2010–11

Summary

Introduction

Pneumococcal infections, including invasive pneumococcal diseases (IPD), such as bacteremia and meningitis, cause a significant morbidity and mortality in adults [1]. In 2000, a 7-valent pneumococcal conjugate vaccine (PCV7) was introduced to the national pediatric immunization program (NIP) in the USA. This resulted in a rapid and dramatic decrease in IPD, both in children and in adults (through an indirect, herd protection effect) [4]. These indirect effects in Europe were not always consistent with the USA experience and varied from country to country [5,6,7,8,9]. We report data on adult invasive pneumococcal disease (IPD), two years post PCV7 implementation and before an expected effect of PCV13

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