In a statement, NIH said: "COVAXIN comprises a disabled form of SARS-CoV-2 that cannot replicate but still stimulates the immune system to make antibodies against the virus."

"Published results(link is external) from a Phase 2 trial of the vaccine indicate that it is safe and well tolerated. Safety data from a Phase 3 trial of COVAXIN in 25,800 participants in India will become available later this year," read the statement.

"Meanwhile, unpublished interim results from the Phase 3 trial indicate that the vaccine has 78% efficacy against symptomatic disease, 100% efficacy against severe COVID-19, including hospitalization, and 70% efficacy against asymptomatic infection with SARS-CoV-2, the virus that causes COVID-19," it said.

"Results from two studies of blood serum from people who had received COVAXIN suggest that the vaccine generates antibodies that effectively neutralize the B.1.1.7 (Alpha) and B.1.617 (Delta) variants of SARS-CoV-2, first identified in the United Kingdom and India, respectively," the statement said.

“Ending a global pandemic requires a global response,” said Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), part of NIH. “I am pleased that a novel vaccine adjuvant developed in the United States with NIAID support is part of an efficacious COVID-19 vaccine available to people in India.”