Electronically delivered letter reminders emphasizing the potential benefits of receiving the flu vaccine increased vaccination uptake among older adults in Denmark, according to a study in The Lancet.
NUDGE-FLU (Nationwide Utilization of Danish Government Electronic Letter System for Increasing InFLUenza Vaccine Uptake) was a randomized, pragmatic, nationwide, register-based trial based on the 2022-20223 flu season. It examined the effect of digital behavioral “nudges” on flu vaccine uptake, particularly based on the presence of cardiovascular disease and across cardiovascular subgroups, including heart failure, ischemic heart disease and atrial fibrillation. The analysis included 691,820 households (964,870 individuals aged 65 or more years).
Of the 964,870 NUDGE-FLU participants from 691,820 households, 264,392 (27.4%) had cardiovascular disease. The researchers found that targeted electronic letter interventions emphasizing the potential cardiovascular benefits of flu vaccination increased vaccination rates among older adults with cardiovascular disease by +0.89 percentage points.
The cardiovascular gain-framed letters were particularly effective among participants who had not been vaccinated for flu in the previous season.
A general reminder letter strategy, consisting of multiple letters at randomization and 14 days later, also was effective in increasing flu vaccination by +0.79 percentage points whether or not cardiovascular disease was present.
The researchers concluded that targeted electronic letter interventions emphasizing the potential cardiovascular benefits of flu vaccination and a general reminder letter strategy were similarly beneficial in increasing flu vaccination rates among older adults with and without cardiovascular disease and across cardiovascular subgroups.
“Although the magnitude of effectiveness was modest, the low-touch, inexpensive and highly scalable nature of these electronic letters might be informative for future public health campaigns,” they wrote.
