Effectiveness of three pneumococcal conjugate vaccines to prevent invasive pneumococcal disease in Quebec, Canada.

BACKGROUND: In Quebec, a pneumococcal conjugate vaccine (PCV) program was implemented in December 2004. The recommended schedule is 2+1 doses for low-risk infants. PCV-7 was first used (including catch-up for children <5 years of age), replaced by PCV10 in June 2009, and by PCV13 in January 2011 (no catch-up in both instances). From the beginning, >90% of children received the recommended number of doses.

OBJECTIVE: To assess the effectiveness of the three PCVs sequentially used to prevent invasive infectious disease (IPD).

METHODS: IPD cases in children 2-59 months during the years 2005-2013 were eligible. Controls were randomly identified in the provincial health insurance registry. Parents were interviewed and immunization records reviewed. Vaccine effectiveness (VE) was computed using multivariate logistic regression models.

RESULTS: Out of 889 IPD cases reported, full participation was obtained for 516 cases (58%) and for 1767 controls. Against vaccine-type IPD, VE (≥1 dose) was 90% (82-95%) for PCV7, 97% (84-99%) for PCV10 and 86% (62-95%) for PCV13. Against 19A IPD, VE was, respectively, 42% (-9% to 69%), 71% (24-89%), and 74% (11-92%). VE (≥2 doses) against PCV13-type IPD was 85% for PCV10 (66-94%), 85% for PCV13 (55-94%), and 89% (58-97%) for a mixed PCV10+PCV13 schedule.

CONCLUSIONS: All three PCV vaccines showed high level of protection against IPD caused by serotypes included in their formulation and there was a high level of cross-protection against 19A for PCV10. No substantial difference was seen between PCV10, PCV13, or a mixed PCV10+PCV13 schedule.