Carriage of Streptococcus pneumoniae 3 Years after Start of Vaccination Program, the Netherlands

University Medical Center, Utrecht, the Netherlands.
Emerging Infectious Diseases (Impact Factor: 6.75). 04/2011; 17(4):584-91. DOI: 10.3201/eid1704.101115
Source: PubMed


To evaluate the effectiveness of the 7-valent pneumococcal conjugate vaccine (PCV7) program, we conducted a cross-sectional observational study on nasopharyngeal carriage of Streptococcus pneumoniae 3 years after implementation of the program in the Netherlands. We compared pneumococcal serotypes in 329 prebooster 11-month-old children, 330 fully vaccinated 24-month-old children, and 324 parents with age-matched pre-PCV7 (unvaccinated) controls (ages 12 and 24 months, n = 319 and n = 321, respectively) and 296 of their parents. PCV7 serotype prevalences before and after PCV7 implementation, respectively, were 38% and 8% among 11-month-old children, 36% and 4% among 24-month-old children, and 8% and 1% among parents. Non-PCV7 serotype prevalences were 29% and 39% among 11-month-old children, 30% and 45% among 24-month-old children, and 8% and 15% among parents, respectively; serotypes 11A and 19A were most frequently isolated. PCV7 serotypes were largely replaced by non-PCV7 serotypes. Disappearance of PCV7 serotypes in parents suggests strong transmission reduction through vaccination.

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Available from: Elisabeth Sanders, May 31, 2015
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    • "In the pre-PCV7 era, 19F and 19A were among the most common serotypes involved in AOM worldwide (Rodgers et al., 2009). Nowadays, multiresistant S. pneumoniae 19A isolates remain the most commonly encountered in many countries, while the number of 19F infections has greatly diminished (Hanage et al., 2011; Spijkerman et al., 2011). Evidence that serotype 19A is well capable of colonizing the nasopharynx and causing AOM has recently been reported using a chinchilla otitis media model (Laufer et al., 2010). "
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    • "However, the effect on overall carriage was marginal owing to serotype replacement by the untargeted types. No significant overall decline has been observed in most nasopharyngeal carriage studies assessing the impact of vaccination with the PCV7 [8,9], however, some did [43,52]. This apparent difference to our model could be due to various reasons, including the lack of power in most studies to detect this rather small decline. "
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