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Covaxin shows early promise

Preliminary results from the human clinical trials of the indigenously developed Covid-19 vaccine, Covaxin, suggest that the drug does not have adverse side effects, says Dr C.M. Singh, the principal investigator leading the human trials at the All India Institute of Medical Sciences (AIIMS) Patna. This is the first coronavirus vaccine to be tested on humans in India, and has been developed by the Indian Council of Medical Research (ICMR) in partnership with Bharat Biotech International. The vaccine was developed from a strain of SARS-CoV-2 isolated by ICMR-National Institute of Virology, Pune.

The ICMR has chosen 12 institutes to conduct the trials, including AIIMS Patna. In the first phase, the vaccine is being tested on a total of 375 volunteers, including 45 at AIIMS Patna. The first volunteer was given the first dose of the vaccine in the second week of July. In an exclusive conversation with INDIA TODAY, Dr Singh says that while 113 volunteers had initially been registered at AIIMS Patna for the trials, the vaccine is being tested on only 45, with the others being excluded on health grounds.

“Two doses of the vaccine are being given to each volunteer. The first vaccine shot—called the zero dose—has already been given to all 45 healthy adults, aged 18 to 55, at AIIMS Patna. Thirty two volunteers at AIIMS Patna have also been given the second dose of the vaccine, 14 days after they received the first shot. So far, only three volunteers have [described adverse side effects like] pain at the site of the injection. [However] as the doses are intramuscular, some pain is usually normal,” Dr Singh says. INDIA TODAY has also spoken to one 54-year-old volunteer at Patna who received the second booster shot of the vaccine on July 29. “I am fine and without any issues,” he says.

Having observed the volunteers for two hours immediately after administering the vaccine, the professionals at AIIMS Patna have also been keeping a close watch on their health since they returned to their homes. Doctors speak with volunteers on the phone twice a day, and have also asked them to maintain a diary with records of any health issues they have experienced since receiving the vaccine. “But the pages are blank, there is nothing to write about,” says a volunteer.

Dr Singh says that the ongoing phase 1 study will be completed after all 375 volunteers are administered the second dose. Their samples from Patna have already been shared with the ICMR after they received the first shot. The process will be repeated after all 45 receive the second shot. Dr Singh says he is hopeful of beginning the second phase of clinical trial by the last week of August or in early September. Then, the ICMR will evaluate the vaccine results with the Drugs Controller General of India (DCGI). After that, they will together give a go-ahead for the second phase.

The goal of the vaccine is to trigger the production of neutralising antibodies in volunteers. Ideally, doctors are hoping to see a level of antibody production that can inactivate the virus in lab tests. “As we have injected [volunteers with] the antigen, it is certain to induce the immune response and produce antibodies. These levels will be measured to compare them against the levels of antibodies [in the blood of] patients who have recovered from coronavirus infections,” says Dr Singh. (Antibodies are proteins produced by the immune system in response to an infection, and are specific to that particular infection—in the case of Covid-19, a type of antibody called immunoglobulin G (IgG) is tested.)

As safety is the primary concern in the first phase of human trials, the indigenous Covid-19 vaccine appears to have fulfilled the test’s parameters. Once this has been officially confirmed, the second phase of trials will begin, in which the efficacy of the vaccine will be assessed as well. If the results of these trials are encouraging, the vaccine will be examined for its capacity to protect people from the coronavirus through larger-scale trials. – India Today