Association of Influenza Activity and Environmental Conditions With the Risk of Invasive Pneumococcal Disease

Key Points Question What is the association of influenza activity and environmental conditions with invasive pneumococcal disease risk in temperate countries, and are these associations generalizable? Findings In this case-crossover study of 19 566 patients from Australia, Canada, and the United States, influenza activity was associated with a short-term increase in risk of invasive pneumococcal disease, while absolute humidity was associated with a short-term decrease in invasive pneumococcal disease risk. These results were generalizable across the 3 temperate countries. Meaning This study’s finding that influenza was associated with increased risk of invasive pneumococcal disease has important implications for disease control policy and practice.