Impact of pneumococcal polysaccharide vaccine in people aged 65 years or older

To evaluate the impact and effectiveness of the 23-valent polysaccharide pneumococcal vaccine (23vPPV) in ≥ 65-year-old Australians in the context of concurrent 7-valent pneumococcal conjugate vaccine (7vPCV) use in infants.

Ecological analysis of trends in invasive pneumococcal disease (IPD) notification rates and vaccine effectiveness estimation using the screening method, using data on Australians aged ≥ 65 years (23vPPV funded) and 50-64 years (23vPPV not funded).

National 23vPPV program for people aged ≥ 65 years and national 7vPCV program for infants, both commencing in 2005.

IPD incidence rate ratios, 2002-2004 to 2010-2011, and 23vPPV effectiveness against 23vPPV-type IPD.

The proportion of people aged ≥ 65 years who were vaccinated within the previous 5 years in jurisdictions excluding Victoria ranged from 41% to 64% over the study period, with no clear trend over time. Incidence rate ratios in the ≥ 65-year age group were 0.11 (95% CI, 0.09-0.14) for 7vPCV serotypes, 1.64 (95% CI, 1.41-1.91) for 23vPPV-non-7vPCV serotypes and 2.07 (95% CI, 1.67-2.57) for non-23vPPV serotypes. The incidence rate ratio for total IPD was 0.65 (95% CI, 0.59-0.71) for people aged ≥ 65 years, and 0.80 (0.71-0.90) for people aged 50-64 years. The estimate of 23vPPV effectiveness was 61.1% (95% CI, 55.1%-66.9%).

The greater reduction in IPD among ≥ 65-year-olds compared with 50-64-year-olds did not reach statistical significance. However, vaccine effectiveness was significant. Greater reductions in IPD in ≥ 65-year-olds would be expected from the indirect effects of using 13-valent pneumococcal conjugate vaccine in infants (introduced for Australian infants in 2011) and an increase in 23vPPV coverage.