The impact of government-mandated proof of vaccination requirements on COVID-19 vaccine uptake

By Shanet Susan AlexReviewed by Danielle Ellis, B.Sc.Jun 6 2022

In a recent work posted in the Nature Human Behavior journal, researchers analyzed the impact of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination mandate on vaccine uptake.

Background

Vaccination has proven to be particularly effective in decreasing the transmission and severity of SARS-CoV-2 infection, with vaccinated individuals having a significantly lower chance of severe consequences. Nonetheless, CoV disease 2019 (COVID-19) vaccinations in several countries noticeably dropped in the summer months after a high surge in early 2021. Due to the enhanced reproduction rate of the SARS-CoV-2 Delta variant, even regions with heightened vaccination rates witnessed elevated viral spread or had to continue or reinstate non-pharmaceutical measures such as indoor capacity restrictions or mask-wearing in fall 2021.

As a result, achieving high COVID-19 vaccine coverage is critical for lowering the economic and health consequences of the epidemic. Increasing vaccine uptake has been a concern for public health officials internationally, particularly within the hesitant or postponing populations. In the light of this problem, several local and national governments have enacted proof-of-vaccination certificates or mandates, allowing vaccinated people to attend non-essential social and sports venues and events like stadiums, concerts, restaurants, museums, and bars. These regulations have two goals: to encourage vaccinations and minimize virus transmission in high-risk indoor or crowded environments.

About the study

In this work, the researchers examined and quantified the influence of government-mandated evidence of COVID-19 vaccination prerequisites for admission to public settings and non-essential enterprises on SARS-CoV-2 first dose vaccine uptake in 10 Canadian provinces and three European nations (Italy, France, and Germany).

Some regulations allow enterprises to opt-out if they follow additional restrictions or consider a past positive or recent negative SARS-CoV-2 test report as a substitute for vaccination. The mandates in Italy, France, Germany, Saskatchewan, and Alberta, among the jurisdictions analyzed by the authors, allowed for such choices during the study period. The team selected the present locations as they hold comparable demographics, economies, and vaccine availability. Moreover, all implemented and announced mandates from July to October 2021 (a timeframe with little binding vaccine supply or access limitations) and had a strong base first-dose vaccination frequency.

The investigators assessed how the mandates affected persons who stayed unvaccinated for months or weeks following SARS-CoV-2 immunization became accessible, such as vaccine-hesitant people. Since the initial doses of the COVID-19 vaccine most directly depict the choice to be vaccinated, the team utilized them as the primary outcome in the statistical evaluation.

They also calculated the extent of the rise in first-dose vaccinations following the announcement of a mandate, taking into account other possible causes. In addition, the researchers analyzed the duration of these vaccination gains and the overall influence on vaccine uptake.

Results

The team discovered that the COVID-19 vaccine mandate announcement was linked to a quick and substantial spike in new vaccinations (an over 60% hike in weekly first doses), utilizing the variance in the timelines of these metrics throughout Canadian provinces in a difference-in-differences (DID) strategy. Time-series assessment of each Canadian province and Italy, France, and Germany supported these results.

Following the mandate's release, vaccination uptake increased significantly in all four of Canada's most populated provinces and three European countries, frequently opposite to a substantial fall in the weeks leading up to the announcement. Daily first-dose consultations dramatically increased the day following the mandate was announced in France. On the other hand, Spain illustrated a consistent drop in initial doses per week throughout the timeframe shown.

As of October 31, 2021, counterfactual simulations based on current estimates imply the succeeding cumulative increases in the vaccination rate across the eligible population, i.e., those aged 12 and older: about five percentage points (p.p.) for Canadian provinces, totaling 979,000 (ranging from 425,000 to 1,266,000) first doses for Canada (five to 13 weeks following provincial requirement notifications); eight p.p. (varying from 4.3 to 11) for France (16 weeks after the announcement); 12 p.p. (ranging from five to 15) for Italy (14 weeks following the announcement); and 4.7 p.p. (spanning 4.1 to 5.1) for Germany (11 weeks post-release).

Conclusions

Overall, the study findings demonstrated that government-assigned evidence-of-vaccination criteria or certificates in Canada, Italy, Germany, and France had drastic and statically relevant effects on COVID-19 vaccine uptake. Besides, these influences were associated with considerable elevations in first-dose vaccinations in the initial several weeks following the mandate's announcement and long-term cumulative improvements compared to the pre-announcement pattern. This incorporates strong DID evidence based on differences in mandate release timing inside the same nation, Canada. The present findings were similar in magnitude to those of other researchers who used different methodology and data samples.

The estimated impact of the mandate on vaccine uptake differs per province in Canada, with the timeframe of release and implementation and the proportion of unvaccinated people all playing a factor. Furthermore, it also varied throughout France, Italy, and Germany. The authors noted that this study could benefit from more investigations justifying this variability and several possibly crucial aspects.