COVID-19 Vaccines developed abroad will undergo bridging studies to prove safety, immunogenicity: Dr Harsh Vardhan

Covishield is in Phase-2 and Phase-3 human trials and, if successful, will be mass produced by Pune-based Serum Institute of India (SII), one of the world's largest manufacturers of vaccines. Its trials in India are running at 17 locations across the country.

A UK media report earlier this month said Covishield, which is also being tested there, could be cleared by health regulators in that country by end-2020 and be rolled out within six months.

Besides, two other vaccine candidates are also being tested across the country.

Indigenous vaccine developer Bharat Biotech, in collaboration with the the Indian Council of Medical Research and the National Institute of Virology, is conducting Phase-1 and Phase-2 clinical trials of vaccine candidate COVAXIN.

The third vaccine candidate under human trial is ZyCoV-D, developed by Zydus Cadila. This candidate is now under Phase-1 and Phase-2 of clinical trials.

The World Health Organisation (WHO) released the 'Draft landscape of Covid-19 candidate vaccines', on September 30, in which it informed that as many as 191 vaccine candidates are in various stages of development across the globe. Among these, 41 have made their way into clinical trials while 10 have entered the third phase of clinical trials.