Antibodies against COVID-19 weakened six months after recipients got fully vaccinated with Covaxin, Covishield or a mixture of both – Covishield being the first dose and Covaxin the second – with regard to the Omicron variant, a new study has found.
The study, conducted by the National Institute of Virology (NIV), Pune, noted however that administering Covishield as the first dose followed by Covaxin as the second produced a good neutralising effect against the Delta variant among others, Pragya Yadav, a scientist at NIV, was quoted as saying by news agency PTI.
Study Comprised 3 Groups
The study was conducted on three groups of people – a heterologous group comprising 18 people who were administered Covishield as the first dose and Covaxin as the second, and two groups with 40 people who were administered both doses of homologous Covishield or Covaxin.
"All the three groups were closely monitored. When we analysed the cohorts in June last year, the heterologous vaccination regimen of administering the first dose of Covisheid, followed by the second dose of Covaxin showed a very good neutralising antibody response against Delta and other Variants of Concern, as compared to the two other cohorts," Yadav added.
She also said that when the recipients' responses were analysed in December 2021, a significant fall in neutralising antibodies was discovered in all three groups with regard to the Omicron variant of COVID-19.
She added that the findings suggest the need for a booster dose for better protection against the Omicron variant, PTI reported.
The Union Health Ministry on 14 March announced that it was removing the comorbidity clause to receiving precautionary doses of COVID-19 vaccine, making everyone aged 60 or above eligible for the dose.
(With inputs from PTI.)
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