Abstract
The 7-valent pneumococcal conjugate vaccine (PCV7) was introduced in The Netherlands in 2006 and was replaced by PHiD-CV10 in 2011. Data on carriage prevalence of S. pneumoniae serotypes in children and invasive pneumococcal disease (IPD) in children and older adults were collected to examine the impact of PCVs on carriage and IPD in The Netherlands. Pneumococcal carriage prevalence was determined by conventional culture of nasopharyngeal swabs in 24-month-old children in 2015/2016. Data were compared to similar carriage studies in 2005 (pre-PCV7 introduction), 2009, 2010/2011 and 2012/2013. Invasive pneumococcal disease isolates from hospitalized children <5 years and adults >65 years (2004–2016) were obtained by sentinel surveillance. All isolates were serotyped by Quellung. Serotype invasive disease potential was calculated using carriage and nationwide IPD data in children. The overall pneumococcal carriage rate was 48% in 2015/2016, lower than in 2010/2011 (64%) and pre-vaccination in 2005 (66%). Carriage of the previously dominant non-vaccine serotypes 19A and 11A has declined since 2010/2011, from 14.2% to 4.6% and 4.2% to 2.7%, respectively, whereas carriage of serotypes 6C and 23B has increased (4.2% to 6.7% and 3.9% to 7.3%), making serotypes 6C and 23B the most prevalent carriage serotypes. IPD incidence declined in children (20/100,000 cases in 2004/2006 to 6/100,000 cases in 2015/2016) as well as in older adults (63/100,000 cases to 51/100,000 cases). Serotypes 6C, 23B and 11A have high carriage prevalence in children, but show low invasive disease potential. Serotype 8 is the main causative agent for IPD in older adults (11.3%). In conclusion, 10 years after the introduction of pneumococcal vaccination in children in The Netherlands shifts in carriage and disease serotypes are still ongoing. Surveillance of both carriage and IPD is important to assess PCV impact and to predict necessary future vaccination strategies in both children and older adults.
Highlights
Infection with Streptococcus pneumoniae is one of the leading causes of respiratory tract infections such as otitis media and pneumonia, as well as invasive disease including bacteremic pneumonia, meningitis and sepsis [1]
Male sex (Number (%)) Mean age in months (SD) Pneumococcal carriage (Number (%)) Presence of siblings
The Netherlands is one of the few EU countries that switched from PCV7 to PHiD-CV10 instead of PCV13
Summary
Infection with Streptococcus pneumoniae is one of the leading causes of respiratory tract infections such as otitis media and pneumonia, as well as invasive disease including bacteremic pneumonia, meningitis and sepsis [1]. Widespread PCV vaccination of infants and toddlers leads to a reduction in carriage and disease caused by vaccine serotypes in all age groups (herd protection) [3,4,5,6]. Determining serotype carriage in children is useful for monitoring eradication of vaccine serotypes in the population after PCV introduction, and for predicting serotypes causing disease in children as well as in other age groups [7, 8]. Comparison of carriage with IPD data shows which serotypes are more invasive and may help to predict if emerging non-vaccine carriage serotypes will become important causes of severe disease. Highly invasive serotypes, for example serotype 1, are rarely found in carriage, and secular trends in serotypes are still hard to predict, but may have an important impact on overall disease incidence [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
