The Effectiveness of COVID-19 Vaccines in Preventing Hospitalizations During the Delta Wave: A Patient-Population Study at a Major Referral Center.

Background and objective Coronavirus disease 2019 (COVID-19) has turned into a deadly global pandemic since its first discovery in Wuhan, China in December 2019. Safe and effective vaccines against COVID-19 have been introduced to the public and have been shown to reduce the severity of the disease and related mortality rates. COVID-19 vaccination was first introduced in Lebanon in mid-February 2021. In this study, we analyzed the effectiveness of vaccination against COVID-19-related hospitalization during the Delta wave at a major referral center in Lebanon. Methods This patient-population study was conducted on patients hospitalized with COVID-19 between July 1, 2021, and September 30, 2021, at the Rafik Hariri University Hospital (RHUH) in Beirut, Lebanon. Data were collected directly from the patients or from digitized records and included demographic characteristics (age, sex, and comorbidities), vaccination status, oxygen requirement, and outcomes. National vaccination data were collected from the daily bulletin provided by the Lebanese Ministry of Public Health. The data collected were analyzed using SPSS Statistics Version 19.0 (IBM Corp., Armonk, NY). Results A total of 289 patients were included in the study, of whom 90.3% were unvaccinated and 9.7% were vaccinated with at least one dose of a two-dose regimen. Only 4.5% of the 289 patients were fully vaccinated. Among those fully or partially vaccinated, the mean time from symptom onset to hospitalization was shorter but the hospital stay was longer compared to the unvaccinated group. The mortality rate was higher in the unvaccinated group (25.7%) compared to 14.3% among the vaccinated. The vaccine effectiveness compared to the national vaccination rate (22.5% in the population after the first and second dose) was 71.71% and 83.78% respectively. Conclusion The findings of this study highlight the fact that complete/partial vaccination against COVID-19 was highly protective against severe disease and hospitalization during the period with a predominance of the Delta variant in Lebanon.