Antibody levels rose steadily after two Pfizer shots and a J&J shot, and were at higher levels after four weeks.
Two other booster shots with vaccines made by Pfizer/Biontech and Moderna have already been approved for use in the EU.
Prime Minister said that the world is battling with COVID-19 and the Quad members again came together in the interest of humanity.
J&J has tied up with Hyderabad-based Biological E for the global supply chain network, hoping to supply its Covid-19 vaccine Janssen through extensive collaborations and partnerships.
J&J’s single dose vaccine has also been slated as a crucial component in the coming days as it may be logistically easy to administer.
India’s pool of Covid-19 vaccines is set to receive a shot in the arm with two more approaching the apex drug regulator for approval.
US Ambassador Randy Berry handed over the vaccines to Health Minister Krishna Gopal Shrestha on Monday.
As India reeled from a devastating second wave of coronavirus infections, the US rapidly deployed six planeloads of life-saving supplies in support of the country's fight against the pandemic.