In the first month, the vaccine's effectiveness against delta variant was 93%, and four months later it declined to 53%. For other Covid variants, the efficacy declined from 97% to 67%.
Central Drugs Standard Control Organisation (CDSCO) has given approval for a study to be conducted by the Christian Medical College (CMC), Vellore on mixing of Covid-19 vaccines- Covaxin and Covishield, official sources said on Wednesday.
Mixing Covaxin and Covishield would give better immunogenicity
An expert panel of the CDSCO, on July 29 had recommended granting permission for conducting the study. The trial will involve 300 healthy volunteers.
The aim of the study is to assess the feasibility on whether a person can be given two different vaccine shots, one each of Covishield and Covaxin, to complete the inoculation course.
Separately, a recent study by the Indian Council of Medical Research (ICMR) involving 98 people, 18 of whom had inadvertently received Covishield as the first dose and Covaxin as the second in Uttar Pradesh, showed that combining these two Covid-19 vaccines elicited better immunogenicity than two doses of the same vaccine.
The study also found that immunisation with a combination of Covishield and Covaxin was safe and the adverse effects were also found to be similar when compared to the same dose regimen.
Meanwhile, more than 53.24 crore Covid-19 vaccine doses have been provided to states and UTs so far and a further 72, 40, 250 are in the pipeline, Union Health Ministry said on Wednesday.
The ministry also added that over 2.25 crore Covid-19 vaccines are still unused and are available with states, UTs and private hospitals.
Published: August 11, 2021, 13:14 IST
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