[Invasive pneumococcal disease in Norway 2004–23 and choice of vaccine for older adults]

Invasive pneumococcal disease (IPD) can be prevented with serotype-specific vaccines. The level of protection depends on which serotypes are in the vaccine and which serotypes are circulating. The purpose of this study was to describe how the epidemiology of IPD has changed since the introduction of the pneumococcal vaccine in the Childhood Immunisation Programme in Norway in 2006, and how the epidemiology impacts the choice of vaccine for older patients.

The study is based on cases of IPD in Norway in the period 2004-23, as reported to the Norwegian Surveillance System for Communicable Diseases (MSIS).

A total of 13,767 cases of IPD were reported during the study period. In the < 5 years age group, the incidence rate decreased from 28.9 (per 100,000) in 2004 to 8.6 in 2023, representing a reduction of 70 % (incidence rate ratio 0.3 (95 % confidence interval (CI) 0.2-0.4)). In the ≥ 65 years age group, the incidence rate fell from 78.0 to 35.2, corresponding to a reduction of 55 % (incidence rate ratio 0.5 (95 % CI 0.4-0.5)). After 2014, the five most common serotypes in the ≥ 65 years age group were 22F, 3, 8, 9 N and 23B.

Despite an indirect effect from the Childhood Immunisation Programme, there remains a residual disease burden of IPD in older patients that can be prevented through vaccination. The 23-valent polysaccharide vaccine and the 20- and 21-valent conjugate vaccines cover most serotypes that cause IPD in older patients.