Abstract
BackgroundThe ten-valent pneumococcal conjugate vaccine (PCV10) was introduced into the Chilean National Immunization Program (NIP) in January 2011 with a 3+1 schedule (2, 4, 6 and 12 months) without catch-up vaccination. We evaluated the effectiveness of PCV10 on pneumonia morbidity and mortality among infants during the first two years after vaccine introduction.MethodsThis is a population-based nested case-control study using four merged nationwide case-based electronic health data registries: live birth, vaccination, hospitalization and mortality. Children born in 2010 and 2011 were followed from two moths of age for a period of two years. Using four different case definitions of pneumonia hospitalization and/or mortality (all-cause and pneumonia related deaths), all cases and four randomly selected matched controls per case were selected. Controls were matched to cases on analysis time. Vaccination status was then assessed. Vaccine effectiveness (VE) was estimated using conditional logistic regression.ResultsThere were a total of 497,996 children in the 2010 and 2011 Chilean live-birth cohorts. PCV10 VE was 11.2% (95%CI 8.5–13.6) when all pneumonia hospitalizations and deaths were used to define cases. VE increased to 20.7 (95%CI 17.3–23.8) when ICD10 codes used to denote viral pneumonia were excluded from the case definition. VE estimates on pneumonia deaths and all-cause deaths were 71.5 (95%CI 9.0–91.8) and 34.8 (95% CI 23.7–44.4), respectively.ConclusionPCV10 vaccination substantially reduced the number of hospitalizations due to pneumonia and deaths due to pneumonia and to all-causes over this study period. Our findings also reinforce the importance of having quality health information systems for measuring VE.
Highlights
In January 2011, the 10-valent pneumococcal conjugate vaccine (PCV10) was introduced in the Chilean National Immunization Program (NIP) with a 3-doses schedule at 2, 4, 6 months of age with a booster dose at 12 months, and with no catch-up vaccination for older children
We evaluated the effectiveness of PCV10 on pneumonia morbidity and mortality among infants during the first two years after vaccine introduction
vaccine effectiveness (VE) increased to 20.7 (95%CI 17.3–23.8) when ICD10 codes used to denote viral pneumonia were excluded from the case definition
Summary
In January 2011, the 10-valent pneumococcal conjugate vaccine (PCV10) was introduced in the Chilean National Immunization Program (NIP) with a 3-doses schedule at 2, 4, 6 months of age with a booster dose at 12 months, and with no catch-up vaccination for older children. Based on evidence from experimental and observational studies with the different-valent pneumococcal conjugate vaccines, vaccinated infants were expected to have reduced rates on a range of laboratory-confirmed and clinically-suspected pneumococcal disease morbidity and mortality outcomes.[1,2,3,4,5,6,7,8]. The ten-valent pneumococcal conjugate vaccine (PCV10) was introduced into the Chilean National Immunization Program (NIP) in January 2011 with a 3+1 schedule (2, 4, 6 and 12 months) without catch-up vaccination. We evaluated the effectiveness of PCV10 on pneumonia morbidity and mortality among infants during the first two years after vaccine introduction
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