Covishield, Covaxin double doses protect from severe COVID: Study
- 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
- The research took place in 11 hospitals
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.
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.
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.
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.