Impact of a dTcaP booster vaccine awareness campaign initiated by the French national health insurance for adults aged 25 years in 2021

Vaccination schedules differ from country to country. In France, the diphtheria, tetanus, pertussis, poliomyelitis (dTcaP) booster vaccine coverage for adults aged 25 has been lower than those recommended. We evaluated the impact of an awareness campaign undertaken by the French national health insurance system in 2021. A randomized, controlled study with adults residing in the Ardennes region was conducted to evaluate the effect on vaccine coverage of the booster vaccine reminder campaign carried out via letter and/or email and/or SMS. The randomization unit was the municipal administrative area (canton). Ten cantons were grouped into the intervention group (INT) and nine were the control group (CON). Outcomes were the booster vaccine delivery and the consultation of a general practitioner (GP) within 12 months (since the French national health insurance running the campaign suggested patients to consult their GP). A total of 1,975 adults were included (INT: 67.3% vs. CON: 32.7%). Of them, 331 received a booster vaccine (INT: 17.4% vs. CON: 15.5%; p = 0.29), and 1,442 consulted a GP (INT: 73.7% vs. CON: 76.8%; p = 0.14). Those who consulted a GP had more frequent vaccine delivery (INT: 19.1% vs. CON: 10.5%; p