Abstract
Background/Aims: In April 2010 the 7-valent pneumococcal conjugate vaccine (PCV7) was replaced by the 13-valent PCV. We investigated pneumococcal carriage in children eligible for PCV7 or PCV13 and their household contacts. Methods: Eligible families in Hertfordshire and Gloucester were identified and a nasopharyngeal swab obtained from consenting household members between July 2012 and March 2013. Samples were cultured for Streptococcus pneumoniae and serotyped by standard methods. For each serotype the ratio of its prevalence in invasive pneumococcal disease (IPD) to its carriage prevalence (case:carrier ratio, CCR) was calculated. Results were compared with previous carriage studies in 2001/2002 and 2008/2009, before and after PCV7 introduction. Results: 217 households were included. Among <5-year olds 47.7% (95% confidence interval 41.8-53.5) were carrying a pneumococcus compared with 51.0% (95% CI: 44.0-58.0) in 2008/2009 and 48.4% (95% CI: 44.1-52.7) in 2001/2002. The odds of carrying a PCV7 serotype was significantly reduced in 2008/2009 (0.07, 95% CI: 0.03-0.16) and 2012/2013 (0.01 95% CI: 0.00-0.07) relative to 2001/2002, while the odds of carrying any of the extra six PCV13 serotypes increased after PCV7 introduction (1.38, 95%CI: 0.73-2.59) but declined significantly after PCV13 introduction (0.05, 95%CI: 0.01-0.37). The CCRs for the frequently carried serotypes were relatively low, with the highest CCR observed for serotypes 7F, 19A, 3, 8, and 33F. Across the three carriage studies, CCR estimates were stable for nearly all serotypes. Conclusion: Carriage of additional PCV13 serotypes has rapidly reduced post-PCV13 introduction in both vaccinated and unvaccinated individuals with a continued decline in transmission of PCV7 serotypes. Carriage rates in children remain unchanged, but the low CCRs of replacing serotypes would be expected to further reduce overall IPD across all age groups.
| Original language | English |
|---|---|
| Pages (from-to) | 4349-4355 |
| Number of pages | 7 |
| Journal | Vaccine |
| Volume | 32 |
| Issue number | 34 |
| DOIs | |
| Publication status | Published - 23 Jul 2014 |
Bibliographical note
Funding Information:Conflicts of interest statement : SNL has performed contract research on behalf of vaccine manufacturers (GSK, Pfizer, Wyeth (now Pfizer), Baxter and Sanofi Pasteur MSD) for St George's University of London but has not received any personal remuneration. MPES has received support to attend and/or present at conferences, scientific meetings and advisory boards from GSK and Pfizer. Her laboratory has received research funding from GSK and Pfizer. CLS and SNL have received support from Wyeth vaccines (now Pfizer) for conference attendance. AJVH, NJA, PAW, TGH and EM declare no conflict of interests. Funding : This work was supported by the Research and Development Directorate of the United Kingdom Department of Health [Grant number 039/0031]. The views expressed in the publication are those of the authors and not necessarily those of the Department of Health.
Keywords
- Carriage
- Colonisation
- Conjugate vaccine
- Herd immunity
- Nasopharynx
- Pneumococcus
- Post-PCV13
- Streptococcus pneumoniae
- Vaccine impact
