COVID-19 vaccines effectiveness against SARS-CO-V-2 infection among persons attending RT-PCR centre at a Medical College Hospital in Telangana: A case control study
Abstract
Background
In January 2021, India drug regulator issued restricted emergency approval for COVAXIN and COVISHIELD which were manufactured in India. On mid-January 2021, in India, there were 10.5million confirmed cases and 0.15 million deaths.
Objectives
The objectives were to evaluate vaccine effectiveness (VE) of India made Covid-19 vaccines against SARS-CoV-2 infection.
Methods
A test negative case control study was conducted from May 2021 to December 2021 for duration of 8months among people attending an RT-PCR centre at a medical college Hospital for RT-PCR test. The baseline characteristics and RT-PCR report; and preliminary data about vaccine status were collected from the RT-PCR centre. The exposure to vaccination was enquired via Phone call or was checked with data available with the health authorities.
Results
After applying inclusion exclusion criteria, case and control definitions, a total of 380 participants (95cases and 285 controls) were included. The adjusted VE of two doses of COVISHIED vaccine against symptomatic SARS-CoV-2 infection was 52.2% (95% CI, 41.7 to 62.1) and single dose was 40.88% (95% CI, 31.26 to 51.29). The adjusted VE of two doses of COVAXIN vaccine against SARS-CoV-2 infection was 39% (95% CI, 29.40 to 49.27). The overall VE was 48.20% (95% CI, 37.90 to 58.22) for two doses of any vaccines.
Conclusions
India made vaccines were nearly 50% effective. Similar results show by different studies with a margin of 10-25% difference. Further new studies should be conducted as new variants of SARS-CoV-2 are emerging, and we don’t know how the vaccine works against the variants and booster doses were required or not.
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