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

BACKGROUND

Phase III clinical trials have documented the efficacy of the SARS-CoV-2 vaccines in preventing symptomatic COVID-19. Nonetheless, it is imperative to continue analyzing the clinical response to different vaccines in real-life studies. Our objective was to evaluate the effectiveness of five different vaccines in hospitalized patients with COVID-19 during the third COVID-19 outbreak in Mexico dominated by the Delta variant.

METHODS

A test-negative case-control study was performed in nine tertiary-care hospitals for COVID-19. We estimated odds ratios (OR) adjusted by variables related a priori with the likelihood of SARS-CoV-2 infection and its severity.

RESULTS

We studied 761 subjects, 371 cases, and 390 controls with a mean age of 53 years (SD, 17 years). Overall, 51% had a complete vaccination scheme, and an incomplete scheme (one dose from a scheme of two), 14%. After adjustment for age, gender, obesity, and diabetes mellitus, we found that the effectiveness of avoiding a SARS-CoV-2 infection when hospitalized with at least one vaccination dose was 71% (OR 0.29, 95% CI 0.19-0.45), that of an incomplete vaccination scheme, 67% (OR 0.33, 95% CI 0.18-0.62), and that of any complete vaccination scheme, 73% (OR 0.27, 95% CI 0.17-0.43).

CONCLUSIONS

The SARS-CoV-2 vaccination program showed effectiveness in preventing SARS-CoV-2 infection in hospitalized patients during a Delta variant outbreak.

Factors associated with influenza vaccination acceptance in Mexican healthcare workers: A multicenter cross-sectional study

Adherence of healthcare workers (HCWs) to influenza vaccination is far from optimal despite its being the most effective intervention for preventing influenza. In order to evaluate factors associated with influenza vaccination acceptance among Mexican HCWs during the 2017-2018 influenza season, a multicenter cross-sectional study spanning public and private hospitals was conducted. Participants were consecutively invited to answer a self-administered questionnaire. A total of 1513 out of 1553 questionnaires were evaluated. The median age of the participants was 32 (26-44) years and 65.8% were women. Nurses and physicians comprised 53.0% of the surveyed population. Total self-reported adherence to influenza vaccination among HCWs during the 2017-2018 season was 63.5% and varied across participating hospitals (P < 0.001). Factors positively associated with influenza vaccination were incremental doses of influenza vaccine received within the last 5 years (aOR = 1.94, 95% CI = 1.78-2.10), City 3 (aOR = 1.62, 95% CI = 1.19-2.20) and City 1 (aOR = 1.39, 95% CI = 1.02-1.91), whereas factors negatively associated were lack of a previous dose of influenza vaccine (aOR = 0.03, 95% CI = 0.01-0.08) and unawareness of the vaccination campaign (aOR = 0.57, 95% CI = 0.44-0.72). Lack of information and poor communication were barriers identified by both vaccinated and unvaccinated personnel. This study concluded that adherence to influenza vaccination in Mexican HCWs is suboptimal and that the factors associated with receipt of influenza vaccine are similar to those reported in other studies.