Background: In the province of Quebec, Canada, pneumococcal conjugate vaccine (PCV) is offered to all children aged less than 5 years, and a 2+1 schedule (2, 4, and 12 months) is recommended for low-risk infants, with other schedules including a lower number of doses for older children.
Objective: To estimate PCV effectiveness against invasive pneumococcal disease (IPD).
Methods: IPD cases in children aged 2–59 months and reported during the years 2005–2007 were eligible and uninfected controls were randomly identified in the provincial health insurance registry. Parents were interviewed by telephone and immunization records were reviewed. The PCV effectiveness was computed using unconditional logistic regression models adjusting for potential confounders.
Results: 180 IPD cases (60.4% of total reported) and 897 controls were included. Predictors of IPD risk were age, season, high-risk medical conditions, day-care attendance, and low family income. Overall PCV protection (≥1 dose) against IPD caused by any serotype was 60% (95% CI: 38%–75%), and was 92% (83%–96%) against IPD caused by vaccine serotypes. Among low-risk children who received the recommended 2+1 schedule, 6 cases of vaccine failure occurred after the first dose, 1 case after the second dose, and no cases after the booster dose.
Conclusion: These results confirm the effectiveness of PCV after 2 and 3 doses.
From the *Public Health Research Unit, Quebec University Hospital Research Centre, Quebec City, Canada; †Department of Preventive and Social Medicine, Laval University, Quebec City, Canada; and ‡Quebec National Public Health Institute, Quebec City, Canada.
Accepted for publication December 15, 2009.
Supported by a research grant from the Quebec Ministry of Health and Social Service. Additionally, supported by GlaxoSmithKline, Novartis, Sanofi Pasteur, Merck and Wyeth, as well as from governmental agencies including the Quebec Ministry of Health and Social Services, Health Canada, and the Public Health Agency of Canada (to P.D.W.). Also by GlaxoSmithKline and Sanofi Pasteur, as well as from governmental agencies including the Quebec Ministry of Health and Social Services (to N. B.) and grants from Sanofi Pasteur and Chiron (now Novartis) (to G.D.S.).
Josiane Rivard from the Quebec University Hospital Research Centre provided assistance in data collection.
Address for correspondence: Philippe De Wals, MD, PhD, Department of Social and Preventive Medicine, Laval University, 2180 Chemin Sainte-Foy, Quebec City, Canada G1K 7P4. E-mail: Philippe.De.Wals@ssss.gouv.qc.ca.
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