For patients aged 18 to 64 years with chronic diseases, electronically delivered letter nudges increase influenza vaccination rates compared with usual care, according to a study published online Oct. 11 in the Journal of the American Medical Association.

Niklas Dyrby Johansen, M.D., Ph.D., from Copenhagen University Hospital—Herlev and Gentofte in Denmark, and colleagues examined whether electronically delivered letter-based nudges informed by behavioral science could increase influenza vaccination uptake among adults (aged 18 to 64 years) with chronic diseases in a registry-based randomized clinical implementation trial.

A total of 299,881 participants were randomly assigned to receive no letter (usual care) or one of six different behaviorally informed electronic letters.

The researchers found that influenza vaccination rates were higher among those receiving any intervention letter compared with usual care (39.6 versus 27.9 percent).

Influenza vaccination was significantly increased with each individual letter type, with the largest effect sizes seen with a repeated letter sent 10 days after the initial letter and with a letter emphasizing potential cardiovascular benefits of vaccination (41.8 and 39.8 percent, respectively, versus 27.9 percent for usual care). Across major subgroups, there was improvement observed in vaccination rates.

“The results suggest that simple, scalable, and cost-efficient electronic letter strategies may be utilized to encourage positive health behavior at a population level,” the authors write.