Impact of vaccination and risk factors on COVID-19 mortality amid delta wave in Libya: a single centre cohort study

Abstract

Background The Delta variant has led to a surge in COVID-19 cases in Libya, making it crucial to investigate the impact of vaccination on mortality rates among hospitalized patients and critically ill. Aims To study risk factors and COVID-19 mortality rates among unvaccinated and vaccinated adults during delta wave at a single COVID-19 care centre in Tripoli, Libya. Methods The study involved two independent cohorts (n=341). One cohort was collected retrospectively from May 2021-August 2021 and the second cohort was prospectively collected from August 2021-October 2021 and most of them were during the Delta wave. The two cohorts were merged and analysed as one group. Results Most patients were male (60.5%) and 53.3% were >60 years. The vast majority of admitted patients did not have previous COVID-19 infection (98.9%) and were unvaccinated (90.3%). Among vaccinated, 30 patients had one dose and only 3 had two doses. Among patients who received one dose, 58.1% (18/31) died and 41.9% (13/31) survived. Most patients (72.2%) had a pre-existing medical condition. Multivariable prediction model showed that age >60 years was significantly associated with death (odds ratio=2.328, CI 1.456-3.724, p-value=<0.0001). Conclusion Previous infection or full vaccination against COVID-19 significantly reduces hospitalization and death, as most admitted patients were unvaccinated and not previously infected. However, a single vaccine dose may not be adequate, especially for older individuals and those with underlying medical conditions. High-risk older patients with comorbidities should be fully vaccinated and offered up to date bivalent COVID-19 booster doses.