Electronic Reminders Boost Flu Vaccination Rates in Denmark, Especially Among Heart Attack Survivors

A series of clinical trials in Denmark has demonstrated the effectiveness of electronic reminders in increasing influenza vaccination rates, with particularly strong results among heart attack survivors. The research, presented at the American Heart Association's Scientific Sessions 2024 and published in JAMA Cardiology, offers promising insights into improving public health outcomes through simple, targeted messaging.

The study, led by Dr. Ankeet Bhatt of Kaiser Permanente San Francisco Medical Center, involved more than 2 million Danish adults across three clinical trials during the 2022-2023 and 2023-2024 flu seasons. Participants were randomly selected to receive one of several email reminders about flu vaccination or no reminder at all. The researchers found that compared to usual care, those who received any email reminder had higher vaccination rates, with a 1.8% improvement among heart attack survivors and a 1.3% increase among adults without a history of heart attack.

Notably, a message explaining the potential cardiovascular benefits of flu shots proved particularly effective, leading to a 3.9% increase in vaccination among people with a history of heart attack, compared to a 2% increase for those without such history. The impact was even more pronounced among heart attack survivors who had not been vaccinated in the previous flu season, with an improvement rate of nearly 14%.

These findings are significant in the context of current vaccination rates. In Denmark, while about 80% of older adults receive flu shots, only about 40% of younger adults with chronic diseases do so. In the United States, for the 2023-2024 flu season, approximately 45% of adults and 55% of children received at least one dose of the flu vaccine, according to the Centers for Disease Control and Prevention.

The study's results suggest that targeted messaging could be a powerful tool in improving vaccination rates, especially among high-risk groups. Dr. Bhatt emphasized that this strategy should be considered as part of a broader approach to improve cardiovascular prevention and encourage flu vaccination among at-risk patients. However, he also noted that while effective, this method alone did not close all implementation gaps for flu vaccination, indicating that additional strategies may be necessary to fully address this important prevention gap.

The implications of this research extend beyond Denmark. Given the low cost and scalability of email reminders, this approach could potentially be implemented in healthcare systems worldwide to boost flu vaccination rates. This is particularly relevant as annual flu vaccination is recommended by health authorities for most individuals, including those with heart disease, due to its role in preventing flu-related complications and potentially reducing major cardiovascular health problems in people with a history of heart attack.

While the study shows promising results, the researchers acknowledge certain limitations. The analysis was based on a prespecified, secondary analysis across the trials, and the high baseline vaccination rates among older adults in Denmark may not be representative of other parts of the world. Further research is needed to validate these findings in populations with lower vaccination rates, with efforts already underway in the United States.

As healthcare systems worldwide continue to grapple with the challenge of improving vaccination rates, this study offers a practical, evidence-based approach that could have significant public health implications. By leveraging simple electronic reminders tailored to highlight specific health benefits, healthcare providers may be able to make substantial strides in protecting vulnerable populations from the potentially serious consequences of influenza.