SARS-CoV-2 Vaccine Effectiveness in Hospitalized Patients: A Multicenter Test-Negative Case-Control Study.

Area of Science:

• Immunology
• Public Health
• Epidemiology

Background:

• Clinical trials confirm SARS-CoV-2 vaccine efficacy against symptomatic COVID-19.
• Real-world effectiveness data are crucial for understanding vaccine performance in diverse populations.
• The Delta variant dominated the third COVID-19 outbreak in Mexico, necessitating local vaccine effectiveness evaluation.

Purpose of the Study:

• To evaluate the effectiveness of five different vaccines against SARS-CoV-2 infection in hospitalized patients.
• To assess vaccine performance during a specific outbreak wave characterized by the Delta variant.
• To provide real-world evidence on COVID-19 vaccine effectiveness in a Mexican population.

Main Methods:

• A test-negative case-control study was conducted across nine tertiary-care hospitals.
• Odds ratios (OR) were calculated, adjusting for factors influencing SARS-CoV-2 infection risk and severity.
• Data from 761 participants (371 cases, 390 controls) were analyzed.

Main Results:

• Vaccine effectiveness in preventing hospitalization with SARS-CoV-2 infection was 71% for at least one dose.
• An incomplete vaccination scheme showed 67% effectiveness, while a complete scheme demonstrated 73% effectiveness.
• Adjusted analyses accounted for age, gender, obesity, and diabetes mellitus.

Conclusions:

• The SARS-CoV-2 vaccination program proved effective in preventing SARS-CoV-2 infection in hospitalized individuals.
• Vaccine effectiveness was observed even during an outbreak dominated by the highly transmissible Delta variant.
• Real-world data support the ongoing use and importance of COVID-19 vaccination strategies.