A Covid-19 vaccine developed by India’s Bharat Biotech is safe and has shown high levels of antibody response in a mid-stage trial, but follow-on studies are needed to evaluate the shot for children and older people, a peer-reviewed study showed.

The vaccine, India’s first successful home-made shot against Covid-19, has attracted interest from more than 40 countries. The company said last week it had shown 81 per cent efficacy in preventing symptomatic COVID-19, based on interim analysis of late stage trials.

The double-dose vaccine showed significantly higher neutralising antibody responses in Phase II than in Phase I due to the difference in dosing regimens that changed to a 4-week apart injection schedule from a 2-week course, researchers said in the study published in medical journal Lancet.