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.