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

Objective: 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. Design, patients and setting: 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). Intervention: National 23vPPV program for people aged ≥65 years and national 7vPCV program for infants, both commencing in 2005. Main outcome measures: IPD incidence rate ratios, 2002-2004 to 2010-2011, and 23vPPV effectiveness against 23vPPV-type IPD. Results: 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%). Conclusions: 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.