Covishield, Covaxin double doses protect from severe COVID: Study

Covishield and Covaxin significantly reduce the risk of severe COVID-19 and the Delta variant among Indians aged 45 and up, according to the findings of a large study led by the Indian Council of Medical Research (ICMR). The study was recently published as a preprint, pending peer review. 

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The results 

With two doses of Covishield, the overall effectiveness against severe COVID was recorded to be 80%, and with two doses of Covaxin, it was 69%.

Vaccine effectiveness was highest when two doses of both vaccines were separated by 6-8 weeks’ time. There were not enough numbers to gauge a 12-week interval, according to senior author Dr Manoj Murhekar, Director of ICMR–NIE (National Institute of Epidemiology). “The main point here is vaccines are effective. We do not really need a booster immediately as by June this year at least 60% of the country’s population was infected with SARS-CoV2 and vaccination would have served as a boost to the immune system,” he told The Indian Express.

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Dr Pragya Yadav of the ICMR-National Institute of Virology, another senior author, said Covaxin and Covishield were effective against severe COVID-19 during the Delta variant’s dominance in the second wave. 

Tarun Bhatnagar of the ICMR-NIE in Chennai, the study’s lead author, said that increasing vaccine coverage to two doses is critical for controlling the pandemic in the country.

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The research 

The research took place in 11 hospitals between May and July of 2021. 6% of severe COVID cases and 17% of controls (Covid-negative individuals) reported full vaccination, while 16% of cases and 28% of controls reported partial vaccination with Covishield. The full vaccination was found to be effective in 80% of cases. 

With Covaxin, 3.4% of cases and 5.3% of controls reported full vaccination, and 16.3% of cases and 28.3% of controls reported partial vaccination. Meanwhile, full vaccination was found to be effective in 69% of cases.

Researchers from Amrita Institute of Medical Sciences, Kochi; Hamdard Institute of Medical Sciences and Research, New Delhi; AIIMS-Jodhpur; Government Medical College, Nagpur; SRM Medical College, Chennai; JIPMER-Puducherry; Surat Municipal Institute of Medical Education and Research, AIIMS-New Delhi, Rishikesh, and Bhubaneswar; and ICMR-National Institute of Virology, Pune collaborated on the research.