Efficacy of Oxford-AstraZeneca (ChAdOx1 CoV-19) vaccine against Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) cases, hospital admissions, type of variants, and deaths

OBJECTIVE: The Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) epidemic has instigated enormous damage to the global healthcare system and economies. A large number of vaccines have been developed. However, confidence in any COVID-19 vaccine is essential for its sustainable success. The present study aimed to investigate the efficacy of the Oxford-AstraZeneca (ChAdOx1 CoV-19) vaccine against SARS-COV-2 cases, hospital admissions, type of variants and deaths. MATERIALS AND METHODS: This study recorded data using electronic platforms PubMed, Web of Science, World Health Organization, US-Food and Drug Authorities-FDA, Facts sheets, and Pharmaceutical Websites. Initially, 278 articles and reports were identified, and after revising the abstracts, 39 studies, clinical trials and organizations, reports were selected for a detailed analysis. RESULTS: The efficacy of the Oxford-AstraZeneca COVID-19 vaccine against symptomatic COVID-19 cases after the first dose was 60.59% (p=0.00001) and after the second dose was 66.84% (p=0.00001). The highest efficacy was against the Alpha variant 58.80% (p=0.00001) and the lowest efficacy was against the Beta variant 30.83% (p=0.00001). However, the overall efficacy against the SARS-CoV-2 variants after the first dose was 49.20%. The highest efficiency of SARS-CoV-2 variants after the second dose against the Beta (B.1.351) variant was 90.34% (p=0.00001), while the lowest efficacy was against the Omicron (B.1.1.529) variant 46.46% (p=0.00001), with overall efficacy against SARS-CoV-2-2 variants after the second dose 73.73%. The highest efficacy against emergency admission was 94.42% (p=0.00001), while the lowest efficacy was 86.57% (p=0.00001), with overall efficacy against ICU, hospital, and emergency admissions after the second dose was 87.74%. Furthermore, the efficacy of the Oxford-AstraZeneca vaccine against deaths after the second dose was 87.44% (p=0.00001). CONCLUSIONS: The efficacy of the Oxford-AstraZeneca COVID-19 vaccine against symptomatic COVID-19 cases, various variants, ICU, and emergency admissions, and against deaths was high. The present study results provide valuable insights for healthcare workers, policymakers, and researchers about the precise efficacy levels against symptomatic cases, hospitalization, and mortality across the diverse populations and age groups.