Pneumococcal conjugate vaccines caused declines in community-acquired pneumonia (CAP) hospitalizations in children younger than 2 years in the Netherlands, but there was no clear impact apparent in other age groups, reported Annemarie van Deursen, MD, of the University Medical Centre (the Netherlands) Utrecht, and her associates.
In the Netherlands, the 7-valent pneumococcal conjugate vaccine (PCV7) was added to the national infant immunization program in 2006; in 2011, PCV7 was replaced by the 10-valent vaccine (PCV10). The investigators undertook a population-based retrospective study during 1999-2014 on all-cause CAP hospitalizations in all ages, identifying 155,994 CAP hospitalizations.
In children aged 0-6 months, the CAP hospitalization rate ratio (RR) was significant from 2012 onward, with an overall post-PCV RR of 0.62 and a RR of 0.19 at the end of the study period in December 2014. In children aged 6 months-1 year, the RR was statistically significant directly after the introduction of PCV, with an overall post-PCV RR of 0.67 and a RR of 0.47 in December 2014, the investigators wrote.
In none of the other age groups did the overall post-PCV hospitalization RR reach statistical significance.
The association of reductions in CAP hospitalizations in children up to 2 years with the introduction of PCV7 “supports the interpretation for a direct causal effect of PCV7, in line with IPD [invasive pneumococcal disease] results that showed a sustained overall IPD reduction in children,” the investigators said. “Furthermore, [during] each subsequent year of the post-PCV period, the reduction in CAP hospitalization rates increased in line with progressive vaccine-type–IPD reduction in the population and limited replacement by nonvaccine type in childhood IPD.”
Read more in Vaccine (2017 Nov 13. doi: 10.1016/j.vaccine.2017.10.090).