China's Covid-19 vaccine shows promising results in early trials: Report

Days after US drugmaker Moderna announced that Phase-I trial of its Covid-19 vaccine had shown positive results, researchers on Friday reported that a vaccine developed in China appeared to be safe and might protect people from the deadly virus.

According to a report in The New York Times citing early-stage trial, published in online journal Lancet, those who received a single dose of the vaccine produced certain immune cells, called T cells, within two weeks, while the antibodies needed for immunity peaked at 28 days after the inoculation.

The trial was conducted by researchers at several laboratories and included 108 participants aged 18 to 60.

According to the latest data from Johns Hopkins University, the number of coronavirus cases worldwide has gone up to 5,209,266.

Dr Daniel Barouch, director of vaccine research at Beth Israel Deaconess Medical Center in Boston, who was not involved in the work, acknowledged that 'this is a promising data' but added that it is "early data."

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Several teams across the world are in a race to develop a vaccine, considered to be the most effective solution for Covid-19 which has claimed more than 3 lakh lives worldwide.

Apart from Moderna, which announced on Monday about its vaccine showing positive results, Dr Barouch and his colleagues too have published a study showing their prototype vaccine protected monkeys from coronavirus infection.

According to the NYT report, results of just one other human vaccine trial, which has now entered mid-stage human trials have been published in a scientific journal.

The vaccine reported on Friday was made with a virus, called Ad5, modified to carry genetic instructions into a human cell. The cell begins making a coronavirus protein; the immune system learns to recognise the protein and attack it, in theory preventing the coronavirus from ever gaining a foothold.

In these people, "their immune systems will essentially rear up and blunt the effect of the vaccine," said Dr. Kirsten Lyke, a vaccinologist at the University of Maryland who is leading another coronavirus vaccine trial.

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Researchers in China did find that people who had Ad5 antibodies were less likely to develop a strong immune response to the vaccine.

"That may limit the use of this vaccine," said Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine.

"If you're comparing vaccines, the adenovirus ones so far seem to be on the lower end of the spectrum," he added.

However, the results of this vaccine are based on data from a short period, and it is unclear how long its protection might last.

In addition, the researchers reported to have tested three doses and said that the highest dose seemed to be the most effective. But people who got the highest dose also experienced the most side effects, such as pain at the injection site, fever, fatigue, headaches, and muscle pain.