DIGITAL letter interventions have been shown to effectively increase influenza vaccination rates among older adults, and researchers have aimed to refine these interventions and assess whether their effectiveness could be sustained over consecutive influenza seasons.
During the 2023–2024 influenza season, researchers conducted a trial to determine whether behaviorally informed digital letters could consistently boost vaccination rates compared to usual care in citizens aged 65 and older in Denmark.
The study enrolled 881,373 participants (mean age 74.1 ± 6.5 years, 52.1% female), grouped into 649,487 households. Households were randomly assigned in a 2.45:1:1:1:1:1:1 ratio to receive either usual care or one of six behaviorally informed electronic nudges before the vaccination period.
The intervention group, who received electronic letters, showed a slight but significant increase in vaccination rates compared to usual care (76.32% vs. 76.02%; difference of 0.31 percentage points; CI:0.00–0.61; p= 0.007). While no individual letter significantly outperformed the others, all nudges demonstrated a consistent positive effect, especially in participants who had not been vaccinated during the previous season (p= 0.010). Importantly, the results showed that these digital nudges maintained their effectiveness even when used in consecutive seasons (p= 0.26).
In conclusion, electronic letter-based interventions proved effective in increasing influenza vaccination rates among older adults, particularly for those who had skipped vaccination in the prior season. This finding suggests that such interventions are scalable and can be reliably integrated into routine clinical practice to enhance vaccination uptake in high-risk populations. Future research should explore how these strategies can be further optimized for different subgroups and how they can be adapted for other vaccine campaigns.
Katrina Thornber, EMJ
Reference
Johansen ND et al. Electronic nudges for sustained influenza vaccination uptake in older adults: the nationwide randomized NUDGE-FLU-2 trial. Nat Med. 2024;DOI:10.1038/s41591-024-03202-4.
