Objective: To assess the impact of a vaccination campaign that administered five different technologies in a middle-income country with one of the largest Covid-19 epidemics.
Materials and methods: Using data from Mexico's Epidemiological Surveillance System for Viral Respiratory Disease (Sisver) and the design of the vaccine policy in Mexico as a natural experiment, we applied difference-in-differences econometric methods to assess the strategy's effectiveness on transmission, hospitalizations, and mortality rates among adults 60 to 64 years old in Mexico between April and June 2021.
Results: We estimated average effectiveness levels of 60.9% against confirmed cases of Covid-19. Vaccination also decreased hospitalizations and deaths by 62.7 and 62.6%, respectively. After adjusting for vaccination coverage, we found an impact of 79.1, 80.9, and 81.3% reduction in new cases, hospitalizations, and deaths among the vaccinated.
Conclusion: Despite the significant progress in our knowledge of Covid-19 vaccination effectiveness, the available evidence relies mostly on experiences from high-income countries. This study contributes to the scientific literature of Covid-19 vaccination effectiveness in a middle-income country with a multi-vaccine scheme.