Disparities in high schools' vaccination coverage (COVID-19). A natural experiment in the Province of Quebec.

Teenagers' vaccination has become crucial to limit the COVID-19 transmission in the population. To increase the vaccination rate of this age group, a school-based vaccination campaign was launched in Québec, Canada from June 7 to 18, 2021. This study aimed to analyze trajectories of vaccination coverage over time among students attending 37 high schools. The study explored whether school-based vaccination campaigns contributed to the progression of the vaccination coverage and attenuated disparities in vaccination coverage across schools. On average, first dose coverage quickly increased from 30.6% to 81.5% between June 6 and 18, 2021, after the launch of the campaign. As of August 13, 2021, first dose coverage had reached 87.9% and 64.9% for the second dose coverage. Public schools with poorer student populations had 6.5 points of percentage lower first dose vaccination rates (95%CI 0.3%; 12.6%) compared to other schools. A higher level of concern related to the pandemic among students was associated with a 4.3 points of percentage increased coverage (95%CI 0.7%; 8.0%). The initial uneven distribution in first dose coverage decreased dramatically by the end of the campaign. Similar trends were observed for the second dose, although between schools' inequality at the end of the period of observation was significantly larger. The school-based vaccination campaign might have initially contributed to a prompt rise in vaccination coverage and helped the disadvantaged schools to reach similar vaccination coverage as seen in other schools. In addition to being an efficient way to achieve rapidly high vaccination coverage, the school-based approach might contribute to increase equity in vaccination distribution.