A recent study published in JAMA Network Open examined the potential benefits of a high-dose influenza vaccine in reducing cardiopulmonary (CP) events during periods of influenza activity. The study, conducted as a secondary analysis of the INVESTED trial, found that while influenza activity was associated with a higher risk of CP events, the higher dose of the influenza vaccine did not reduce this risk.
The study included patients with high cardiovascular disease (CVD) risk who had previously been hospitalized for myocardial infarction or heart failure. These patients were randomly assigned to receive either a standard-dose or high-dose influenza vaccine. The primary outcome measured was a composite of CP hospitalization or all-cause mortality, with secondary outcomes including pulmonary hospitalization, cardiovascular hospitalization, and death.
The results showed that increased influenza-like illness (ILI) activity in the past week was associated with elevated risks of CP events and cardiovascular hospitalization. However, there was no association between ILI activity and pulmonary hospitalizations or all-cause mortality. Additionally, the high-dose influenza vaccine did not show superiority over the standard dose in reducing the risk of CP events, even during periods of higher influenza or ILI activity.
The study also found that there was an association between warmer months and decreased cardiovascular risk, independent of local ILI activity. This suggests that factors other than influenza may contribute to the association between ILI and CP events.
While the study did not determine the benefit of influenza vaccination relative to placebo, the researchers believe that vaccination would likely be substantially beneficial to placebo in this high-risk population. It is worth noting that other respiratory viruses may also contribute to the association with CP events, as influenza is not the only virus circulating during the winter months.
In conclusion, this study highlights the temporal association between ILI and CP hospitalizations in high-risk CVD patients. However, the higher dose of the influenza vaccine did not reduce this risk. Further research is needed to better understand the factors contributing to CP events during periods of influenza activity.
Source: JAMA Network Open