Vaccination Does Not Prevent Pneumonia In Older People

Pneumococcal polysaccharide vaccination helps to guard older people against life-threatening bacteraemia but offers them little if any protection against pneumonia.

This finding was reporting following a retrospective study of 47,000 people aged 65 years or more.

Streptococcus pneumoniae is the chief cause of pneumonia in older adults. Until now, it has been unclear whether the pneumococcal vaccine alters the overall risk of the acquiring the disease in the community. Dr Lisa A. Jackson from the Center for Health Studies, Group Health Cooperative, and the University of Washington, Seattle, United States, led this 3-year follow-up investigation of the effectiveness of the vaccine.

Primary outcomes were hospitalisation because of community- acquired pneumonia, pneumonia in patients who were not hospitalised ("outpatient pneumonia") and pneumococcal bacteraemia.

Over the 3-year study period, 1,428 of the total of 47,365 participants were hospitalised with community- acquired pneumonia. Of these, 3,061 were diagnosed with outpatient pneumonia and 61 with pneumococcal bacteraemia.

Investigators evaluated the link between pneumococcal vaccination and risk of each outcome via multivariate Cox proportional-hazards models, taking into account a range of factors. These included age, sex, nursing-home residence or non-residence, smoking status, medical conditions and receipt or non-receipt of influenza vaccine.

The pneumococcal vaccination was linked with a significant reduction in risk of pneumococcal bacteraemia. However, over the 3 years of follow-up, there was no reduction in risk of community-acquired pneumonia.

Thus, the findings support the effectiveness of the pneumococcal polysaccharide vaccine for preventing bacteraemia. However, they also point to the need for strategies to prevent non-bacteraemic pneumonia, a more common manifestation of pneumococcal infection in older people, the authors underline.

Other contributors to this study were from the Veterans Affairs Puget Sound Health Care System, also in Seattle, and the Centers for Disease Control and Prevention, Atlanta, Georgia.
N Engl J Med 2003;348:1747-1755.