Impact of vaccination on infection or death from COVID-19 in individuals with laboratory-confirmed cases: Case-control study

Abstract

Objectives The objective of this study is to estimate the effectiveness of COVID-19 vaccines in people treated within the social security system whose vaccination status was reported to the epidemiological surveillance system. Study design Case-control study. Methods This was a case-control study conducted. The records of individuals with suspected cases of COVID-19 registered in the epidemiological surveillance system between February 1 and June 30, 2021, were studied. RT–qPCR was performed to determine SARS-CoV-2 infection; those with a positive result were considered cases, and those with a negative result were considered controls. The ratio between cases and controls was 1:1.3. The crude and adjusted vaccine effectiveness was considered the prevention of symptomatic infection and death and calculated as the difference between the dose and the risk, with a survival analysis among vaccinated people. Results A total of 94,416 individuals were included, of whom 40,192 were considered cases and 54,224 controls; 3,781 (4.00%) had been vaccinated against COVID-19. Vaccination also proved to be a protective factor against COVID-19, especially in the population who received a second dose (OR = 0.31; 95% CI 0.28–0.35). With the application of the vaccine, there was a protective effect against mortality (OR = 0.76; 95% CI 0.66–0.87). Disease prevention was higher for the BNT162-2 mRNA vaccine (82%) followed by the ChAdOx1 vaccine (33%). In the survival analysis, vaccination provided a protective effect. Conclusions There was a positive impact of vaccines for the prevention of symptomatic COVID-19, with a second dose generating greater efficacy and a reduction in deaths.

Association of the Magnitude of Anti-SARS-CoV-2 Vaccine Side Effects with Sex, Allergy History, Chronic Diseases, Medication Intake, and SARS-CoV-2 Infection

“…This was further confirmed by a study involving complete autopsy and microscopic analysis of patient organs [ 45 ]. Such results were also reported upon the occurrence of infections with different variants, including the Omicron variant, upon vaccination with the ChAdOx1, CoronaVac, and BNT162b2 vaccines [ 46 , 47 ].…”

COVID-19 vaccination uptake among healthcare workers in Ghana: A comprehensive analysis of knowledge, attitude, perceived vaccine effectiveness, and health belief model constructs

“…COVID-19 vaccination has remained a complex matter influenced by social, cultural, geographical, and political factors [47,48]. The pandemic resulted in the death of thousands of HCWs [13], which could have been prevented through vaccination [49,50]. However, hesitancy to receive the COVID-19 vaccination was prevalent among HCWs [51][52][53][54], and this impeded efforts to curb the pandemic.…”