Effectiveness of heptavalent pneumococcal conjugate vaccination on invasive pneumococcal disease one year after the introduction in the Danish childhood vaccination programme

Abstract number: P1130

Harboe Z.B., Valentiner-Branth P., Benfield T.L., Christensen J.J., Howitz M., Andersen P., Krogfelt K.A., Glismann S., Lambertsen L., Konradsen H.B.

Objective: On 1 October 2007, the heptavalent pneumococcal conjugate vaccine (PCV7) was introduced in the Danish childhood vaccination program. Vaccination was offered to all children born after 1 April 2006, at 3, 5, and 12 months of age (mo.) (2+1 schedule). A catch-up program of two doses was offered to children between 12–17 mo. We evaluated the effectiveness of PCV7 on invasive pneumococcal disease (IPD) one year after PCV7 introduction.

Methods: Prospective cohort study including nation-wide laboratory surveillance data on IPD and data on PCV7 coverage from the Danish Childhood Vaccination Registry. The pre-PCV7 period was defined as 2000–2007. The effectiveness of PCV7 was estimated for 2008 based on IPD data from 1 January to 15 December 2008. PCV7 coverage was estimated per 1 June 2008. For children aged 0–2 mo. at PCV7 implementation, 94% had received at least one dose and 74% at least two doses. In the catch-up program, 86% of children between 3–14 mo. and 57% between 15–16 mo. received at least one dose.

Results: In 2008, 840 IPD cases were registered vs. an annual average of 1048 cases in the pre-PCV7 period. 90% were bacteraemia cases. The overall incidence of IPD declined from a mean of 19.4 to 15.3 per 100,000 comparing pre- and post-PCV7. In children <2 years (y), the mean incidence declined significantly from 54 to 23 per 100,000 in the pre- and post-PCV7 (p < 0.005). In children <2 y, the mean incidence of IPD caused by vaccine serotypes decreased from 36 to 8 per 100,000. The most prevalent serotype in post-PCV7 was 7F (32%), all other serotypes accounted for less than 6% of cases. In pre-PCV7 period, the most prevalent serotypes were 14 (21%), 6B (20%), 7F (9%), 6A (8%), 19F and 23F (7%). In children between 2–5 y, the overall incidence slightly increased from 8.6 to 11.8 per 100,000. The incidence tended to decline in all other age groups: from 2.5 to 1.2 per 100,000 in persons between 5–18 y, from 7 to 5.8 per 100,000 in persons between 18–50 y, from 23.4 to 17.5 per 100,000 in persons between 50–64 y, and from 65.4 to 52.9 per 100,000 in persons older than 65 y comparing pre- and post-PCV7.

Conclusion: After the universal introduction of PCV7 in Denmark, we observed a decline in the overall incidence of IPD that was statistically significant in children younger than 2 years. In children younger than 2 years, serotype 7F was the dominant serotype in the post-PCV7 period. PCV7 coverage in children younger than 2 years was high.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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