Impact of vaccination against severe COVID-19 in the French population aged 50 years and above: a retrospective population-based study

Laetitia Tan-Lhernould (1) , Cynthia Tamandjou (1) , Guilhem Deschamps (2) , Johnny Platon (2) , Cécile Sommen (2) , Fanny Chereau (1) , Isabelle Parent Du Châtelet (1) , Simon Cauchemez (3) , Sophie Vaux (1) , Juliette Paireau (1, 3)

1 Direction des maladies infectieuses - Infectious Diseases Division [Saint-Maurice]
2 Direction appui, traitements et analyses de données - Data Support, Processing and Analysis Division [Santé publique France, Saint-Maurice]
3 Modélisation mathématique des maladies infectieuses - Mathematical modelling of Infectious Diseases

Background: Given the widespread implementation of COVID-19 vaccination to mitigate the pandemic from the end of 2020, it is important to retrospectively evaluate its impact, in particular by quantifying the number of severe outcomes prevented through vaccination. Methods: We estimated the number of hospitalizations, intensive care unit (ICU) admissions and deaths directly averted by vaccination in France, in people aged ≥ 50 years, from December 2020 to March 2022, based on (1) the number of observed events, (2) vaccination coverage, and (3) vaccine effectiveness. We accounted for the effect of primary vaccination and the first booster dose, the circulating variants, the age groups, and the waning of vaccine-induced protection over time. Results: An estimated 480,150 (95% CI: 260,072–582,516) hospitalizations, 132,156 (50,409–157,767) ICU admissions and 125,376 (53,792–152,037) deaths were directly averted by vaccination in people aged ≥ 50 years, which corresponds to a reduction of 63.2% (48.2–67.6), 68.7% (45.6–72.4) and 62.7% (41.9–67.1) respectively, compared to what would have been expected without vaccination over the study period. An estimated 5852 (2285–6853) deaths were directly averted among the 50–59 years old, 16,837 (6568–19,473) among the 60–69 years old, 32,136 (13,651–36,758) among the 70–79 years old and 70,551 (31,288–88,953) among the ≥ 80 years old. Conclusions: The vaccination campaign in France considerably reduced COVID-19 morbidity and mortality, as well as stress on the healthcare system.

Mots clés: COVID-19; Vaccination; Impact; Mortality; Hospitalization; Burden

Domaines: Santé publique et épidémiologie

Laetitia Tan-Lhernould, Cynthia Tamandjou, Guilhem Deschamps, Johnny Platon, Cécile Sommen, et al.. Impact of vaccination against severe COVID-19 in the French population aged 50 years and above: a retrospective population-based study. BMC Medicine, 2023, 21 (1), pp.426. ⟨10.1186/s12916-023-03119-8⟩. ⟨pasteur-04388691⟩