Data from Phase 3 trials show the vaccine offers 78 percent protection against COVID-19, according to findings published in Lancet.
Covaxin, the first COVID-19 vaccine developed in India, is "highly efficacious” and presents no safety concerns, according to a study published in the medical journal Lancet.
Covaxin gained emergency approval from the World Health Organization last week, the eighth jab to be given the green light by the health body. The vaccine has already been cleared for use in 17 countries.
Known by the code BBV152, Covaxin is an inactivated virus-based COVID-19 vaccine developed by Bharat Biotech in collaboration with the Indian Council of Medical Research and the National Institute of Virology.
The WHO has described it as "extremely suitable for low- and middle-income countries due to easy storage requirements”.
Some of the other approved vaccines must be stored at very low temperatures, which throws up logistical and cost problems.
Covaxin "was highly efficacious against laboratory-confirmed symptomatic COVID-19 disease in adults”, the Lancet study said.
The jab was also "well tolerated with no safety concerns raised in this interim analysis”, it added.
The Indian-developed vaccine has a 78 percent efficacy rate after two doses over a month, according to the WHO.
It has joined the COVID vaccines produced by Pfizer/BioNTech, Moderna, AstraZeneca, Johnson&Johnson, Sinopharm and Sinovac on the WHO-approved list.
The rollout of Covaxin can "increase the finite global manufacturing capacity, and improve insufficient supply of vaccines, which disproportionately affects low-income and middle-income countries,” said Chinese researchers Li Jingxin Li and Zhu Fengcai, who did not take part in the study.
They did however mention certain limits to the study, saying that as the trials had been conducted solely in India, there was a less ethnically diverse study group.
The studies were also carried out between November 2020 and January 2021, before the more contagious Delta variant of the virus became widespread.
Despite the trial dates, the researchers involved were able to identify which of the patients were infected with the Delta variant. For this sub-group, the study found that Covaxin still provided protection against COVID-19, but was slightly less effective.