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COVID-19 vaccine protects monkeys from new coronavirus, Chinese biotech reports

28 Apr, 2020

For the first time, one of the many COVID-19 vaccines in development has protected an animal, rhesus macaques, from infection by the new coronavirus, scientists report. The vaccine, an old-fashioned formulation consisting of a chemically inactivated version of the virus, produced no obvious side effects in the monkeys, and its human trial is about to begin.

Researchers from Sinovac Biotech, a privately held Beijing-based company, gave two different doses of their COVID-19 vaccine to a total of eight rhesus macaques. Three weeks later, the group introduced SARS-CoV-2, the virus that causes COVID-19, into the monkeys’ lungs through tubes down their tracheas, and none developed a full-blown infection.

The monkeys given the highest dose of vaccine had the best response: Seven days after the animals received the virus, researchers could not detect it in the pharynx or lungs of any of them. Some of the lower dosed animals had a “viral blip” but also appeared to have controlled the infection, the Sinovac team reports in a paper published on 19 April on the preprint server bioRxiv. In contrast, four control animals developed high levels of viral RNA in several body parts and severe pneumonia. The results “give us a lot of confidence” that the vaccine will work in humans, says Meng Weining, Sinovac’s senior director for overseas regulatory affairs.

The company recently started phase I clinical trials in Jiangsu province, north of Shanghai, which aim to gauge safety and immune responses in 144 volunteers. An equal number of participants will receive the high and low doses or a placebo. Although placebos are not typically used in phase I studies—which do not assess efficacy—Meng says this can help better evaluate whether the vaccine causes any dangerous side effects. The company hopes to start phase II studies by mid-May that have the same design but enroll more than 1000 people, with results due by the end of June.

According to WHO, six other vaccines had entered human trials as of 23 April, and 77 others were in development. The vast majority of these vaccines use the modern tools of genetic engineering—only four rely on the old-fashioned inactivation technology—but Meng says what ultimately matters is whether a vaccine is safe and effective, not how it’s made. “We are not comparing ourselves to anyone,” Meng says. “In this pandemic situation, the most important thing is to make a vaccine, no matter what kind of vaccine it is, that’s safe and effective as soon as possible.”

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