Impact of a COVID-19 certificate requirement on vaccine uptake pattern and intention for future vaccination. A cross-sectional study among French adults.

Background: In August 2021, France enacted a COVID-19 certificate requirement (vaccination/recovery/test) to access specific services, with mandates for professional groups. We evaluated the impact of this incentive-coercive policy in terms of vaccine uptake equality, future vaccine intention and confidence in authorities' crisis management.

Methods: In late August 2021, a representative sample of adults (18-75 years) completed an internet-based questionnaire. We classified vaccinated participants by stated reasons for vaccination and estimated adjusted prevalence ratios (aPR) using multivariable Poisson regression. Counterfactual vaccine status assumed non-vaccination of those vaccinated for the certificate. We analysed the association of free-text testimonial themes with level of confidence in authorities.

Results: Among 972 participants, 85.7% were vaccinated or intended vaccination: 3.6% only for certificate/mandate, 17.7% mainly for certificate/mandate plus other reasons, and 64.4% mainly for other reasons. In the counterfactual situation, vaccine uptake would have been significantly more likely among older vs. younger participants (aPR = 1.35) and among those with moderate-high vs. low levels of confidence in authorities for COVID-19 crisis management (aPR = 2.04). In the observed situation, confidence was the only significant determinant of vaccine status (moderate-high vs. low, aPR = 1.39). Among those without genuine motivation for vaccination, professionally active persons were more likely to have ceded to the certificate requirement (aPR = 3.76). Those vaccinated only for the certificate were more likely to express future COVID-19 vaccine intention than unvaccinated persons (aPR = 6.41). Themes significantly associated with lower confidence were criticism of morality (aPR = 1.76) and poor communication by the authorities (aPR = 1.66).

Conclusion: The incentive-coercive policy has reduced the negative association of vaccine status with younger age and low confidence in authorities, but may have reinforced isolation of professionally inactive persons. The requirement did not negatively impact future COVID-19 vaccine intention. Future vaccine-incentive policies should pay special attention to populations with low levels of confidence in authorities.