Impact of conjugate 7-valent vaccination in Belgium: addressing methodological challengesArchived

ECDC comment

In Belgium, the 7-valent pneumococcal conjugate vaccine (PCV7) was introduced into the national schedule in 2007.

Hanquet G, Lernout T, Vergison A, Verhaegen  J, Kissling E, Tuerlinckx D et al. Vaccine 2011; 29: 2856–64.

The early impact of PCV7 vaccination on paediatric invasive disease was estimated by comparing pre- and post-vaccination incidence from national surveillance. In children <2 year-olds, vaccine-serotype incidence declined by 96% but non-vaccine-types increased 2–3-fold. Overall invasive disease decreased by 23–46%, depending on adjustment for under-reporting and pre-vaccine trends.

Non-vaccine-types 1 and 19A had increased before PCV7 use, suggesting the contribution of other factors. Estimation of PCV7 impact comparing pre- and post-vaccination data should adjust for pre-vaccine trends, and serotype dynamics need further exploration.