Background: Pneumococcal conjugate vaccine (PCV) is now recommended for use in adults in the United States. Because vaccination of children with PCVs protects adults from the targeted serotypes, local variations in PCV uptake among children could influence disease patterns in adults.
Methods: We obtained ZIP code-level data on invasive pneumococcal disease (IPD) from an active population-based surveillance system in Connecticut (study interval, 1998-2009) and ZIP code-level data on immunization with at least 3 or at least 4 doses of 7-valent PCV (PCV7) from the state immunization registry. We fit logistic regression models to estimate the proportion of IPD cases among adults aged >40 years that were caused by PCV7-targeted serotypes. Covariates included ZIP code-level socioeconomic indicators (eg, percentage of the population that was black and income per capita), the percentage of the population that received 3 or 4 doses of PCV7 (mean centered), and a linear spline to control for the average rate of decline across all ZIP codes.
Results: ZIP codes that had a higher proportion of children that did not complete the 4-dose PCV7 series had a higher proportion of adult IPD cases caused by PCV7 serotypes.
Conclusions: Local variations in PCV uptake (and receipt of the booster dose) might influence the effectiveness of PCVs in preventing pneumococcal disease in adults.
Keywords: conjugate vaccine; herd immunity; indirect effects; pneumococcal.
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