Grant: Project Grant

Influenza causes many deaths and serious illnesses each year, with the greatest impact among older adults. Influenza vaccines are highly recommended for older adults, but vaccine coverage in this population is suboptimal (only ~60% in Canada, and trending downward). Numerous studies have shown that influenza vaccines prevent laboratory-confirmed influenza in both outpatient and inpatient settings during most influenza seasons. However, rigorous evidence that influenza vaccines prevent laboratory-confirmed influenza mortality is surprisingly scarce. High-quality evidence of effectiveness against this outcome is needed. Another potential strategy for mitigating severe influenza infections is the use of statin medications. In addition to lowering cholesterol, statins have wide-ranging effects on the immune system, and they have been proposed for use during influenza pandemics to decrease the inappropriate inflammation that is sometimes seen with severe infections. A recent study found that statin users were less likely to experience laboratory-confirmed infection by H3N2 influenza viruses. On the other hand, that study and two others found statin use seems to decrease the effectiveness of influenza vaccines. Since many older adults take statins, and older adults are recommended to receive influenza vaccines, it is important to sort out the complex relationship between statin use, influenza vaccines, and influenza outcomes.