India’s department of biotechnology has selected 10 cities where several thousand healthy volunteers could join the anticipated large-scale clinical trials to assess the efficacy of candidate vaccines against Covid-19.

A department of biotechnology (DBT) expert panel has identified Hyderabad, Palwal (Haryana), Pune, Tirunelveli (Tamil Nadu) and Vellore as the first set of “field sites” for large-scale — also called Phase 3 — clinical trials and long-term epidemiological studies of the coronavirus infection.

Clinical research institutions at each of these sites could within weeks begin preparatory activities such as surveillance studies to determine the local population’s exposure to the infection, researchers associated with the initiative said.

The first set of institutions are the Inclen Trust, Palwal; King Edward Memorial Medical College, Pune; National Institute of Epidemiology, Tirunelveli; Society for Health and Allied Research, Hyderabad; and the Christian Medical College, Vellore.

The DBT, which operates under the Union science and technology ministry, has also identified two institutions in Delhi and one each in Bhubaneswar, Puducherry, Shillong and Visakhapatnam for similar research.

Safety and efficacy trials for two home-grown candidate vaccines — one developed by the Hyderabad-based Bharat Biotech and the other by the Ahmedabad-based Zydus Cadila — began earlier this month at multiple sites across India.

These trials will examine the safety of the candidate vaccines and their capacity to generate an immune response. If the results of these trials are encouraging, the candidate will be assessed for their capacity to protect people from the infection through the large-scale Phase 3 trials.

“We need to prepare field sites for large-scale clinical trials where we can monitor the efficacy of the vaccine candidates,” Narendra Arora, a senior clinician-researcher and executive director of the Inclen Trust, told The Telegraph.

“We also plan to do follow-up studies on the population for two to three years.”

While the current trials involve only around 1,000 healthy volunteers, the Phase 3 trials will require several thousand volunteers. Each of the field sites chosen has populations of prospective volunteers ranging from 50,000 to 200,000, Arora said.

The Pune-based Serum Institute of India plans to conduct Phase 3 trials of a candidate vaccine developed by University of Oxford researchers that has already undergone Phase 1 and Phase 2 studies with encouraging results in the UK.

Arora said the field sites could be used to test both indigenous and foreign-made vaccines. But, he said, it is too early to say how many volunteers might be picked at any of these sites.

As part of the preparatory activities, researchers plan to initiate sero-surveillance studies to look for antibodies to the SARS-CoV-2, the virus that causes Covid-19, in the local populations at each site.

These studies will provide baseline information about the extent of the infection’s spread and allow researchers to track the infection over time — before and after a vaccine — if and when the vaccine is introduced.

In addition to the Bharat and Zydus candidate vaccines, a presentation made by the DBT to the Union science and technology ministry on Saturday said three other candidate vaccines under development in India were undergoing animal studies and 11 other candidates were in early animal studies.

India on Sunday recorded 54,735 new Covid-19 infections, raising the total number of lab-confirmed cases to 1,750,723, of whom 567,730 patients are under medical supervision, 1,145,629 have recovered and 37,364 have died.