Carriage of S. pneumoniae after Vaccination | CDC EID

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Volume 17, Number 4–April 2011
Research
Carriage of Streptococcus pneumoniae 3 Years after Start of Vaccination Program, the Netherlands
Judith Spijkerman, Elske J.M. van Gils, Reinier H. Veenhoven, Eelko Hak, Ed P.F. Yzerman, Arie van der Ende, Alienke J. Wijmenga-Monsuur, Germie P.J.M. van den Dobbelsteen, and Elisabeth A.M. Sanders

Author affiliations: University Medical Center, Utrecht, the Netherlands (J. Spijkerman, E.J.M. van Gils, E.A.M. Sanders); Spaarne Hospital, Hoofddorp, the Netherlands (J. Spijkerman, E.J.M. van Gils, R.H. Veenhoven); University Medical Center, Groningen, the Netherlands (E. Hak); Regional Laboratory of Public Health, Haarlem, the Netherlands (E.P.F. Yzerman); Academic Medical Center, Amsterdam, the Netherlands (A. van der Ende); and Netherlands Vaccine Institute, Bilthoven, the Netherlands (A.J. Wijmenga-Monsuur, G.P.J.M. van den Dobbelsteen)

Suggested citation for this article

Abstract
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.

Streptococcus pneumoniae (pneumococcus) is a major cause of respiratory and invasive disease worldwide, particularly in children <5 years of age and elderly persons (1). All pneumococcal disease is preceded by nasopharyngeal colonization (2). To date, slightly >90 serotypes have been identified. Young children, among whom nasopharyngeal carriage rates are highest, are the main reservoir for pneumococcal spread in families and the community (3).

In the United States and other industrialized countries, widespread use of the 7-valent pneumococcal conjugate vaccine (PCV7) (Prevenar; Pfizer, New York, NY, USA) for children has led to a dramatic decline in PCV7-serotype invasive pneumococcal disease (IPD), not only in vaccinated children (4) but also in unvaccinated persons of all ages (5,6). This indirect effect has substantially contributed to favorable cost-effectiveness estimates of the vaccination program (7,8). However, shifts toward nasopharyngeal carriage of non-PCV7 serotypes may eventually counterbalance the direct and indirect benefits of the vaccine, assuming that non-PCV7 serotypes will display similar disease potential (9–12). Early evaluation of the effect of pneumococcal vaccination on serotype distribution in disease is hampered by the relative infrequency of IPD and the difficulty of identifying causative agents in respiratory diseases such as pneumonia or in otitis media. Therefore, surveillance of nasopharyngeal carriage of pneumococci in vaccinated and in unvaccinated persons provides another useful tool for monitoring how vaccination affects circulating pneumococcal serotypes.

In the Netherlands, as part of the national immunization program (NIP), vaccination with PCV7 was introduced for all infants born after March 31, 2006, in a 3+1 schedule of vaccinations at 2, 3, 4, and 11 months with no catch-up campaign. To evaluate how this PCV7 vaccination program affected prevalence of pneumococcal serotypes after 3 years, we conducted a cross-sectional observational study of nasopharyngeal carriage of pneumococci, and we compared data from vaccinated children and their parents with data from age-matched pre-PCV7 (unvaccinated) controls.

full-text:
Carriage of S. pneumoniae after Vaccination | CDC EID


Suggested Citation for this Article
Spijkerman J, van Gils EJM, Veenhoven RH, Hak E, Yzerman EPF, van der Ende A, et al. Carriage of Streptococcus pneumoniae 3 years after start of vaccination program, the Netherlands Emerg Infect Dis [serial on the Internet]. 2011 Apr [date cited].
http://www.cdc.gov/EID/content/17/4/584.htm


DOI: 10.3201/eid1704.101115


Comments to the Authors
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Elisabeth A.M. Sanders, Wilhelmina Children's Hospital, University Medical Center Utrecht, Lundlaan 6, 3508 AB Utrecht, the Netherlands; email: l.sanders@umcutrecht.nl