Receiving the flu vaccine and a COVID-19 shot on the same day is not associated with an increased risk of adverse reactions. This conclusion comes from an analysis of medical records for 2.5 million adult patients within the Veterans Affairs (VA) health system.
The study, published in the Annals of Internal Medicine, examined the frequency of 46 different adverse reactions. Researchers compared data from approximately 1.8 million VA patients who received only the flu shot to over 705,000 patients who received both the flu and COVID-19 vaccines simultaneously. This analysis covered the period from September 2022 to August 2025, during which three different versions of the COVID-19 vaccine were available.
The researchers specifically looked for cardiovascular and thrombotic events, neurological disorders, and immune-mediated disorders within 90 days of vaccination. None of these specific outcomes demonstrated a statistically significant increase in risk when vaccines were administered together.
The study’s authors, who are affiliated with the VA St. Louis Health Care System’s Clinical Epidemiology Center, stated that these findings support the short-term safety of giving these vaccines concurrently, particularly in older adults. They believe this information could be valuable for current discussions on vaccine policy and for individuals evaluating their personal risk versus benefit when considering vaccinations.
The researchers also highlighted that, despite decreasing fatality rates, COVID-19 continues to contribute significantly to illness and death in the United States. An estimated 879,000 hospitalizations and 101,000 deaths are attributed to the virus between October 2023 and September 2024.