China's Sinovac sees speedy immune response with COVID-19 shot in early trials

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A week after one of its tests in Brazil was stopped amid a safety scare, Chinese biotech Sinovac has published data showing its experimental COVID-19 vaccine can quickly boost an immune response.

Published in the journal Lancet Infectious Diseases, the phase 1/2 trial for Sinovac’s CoronaVac inoculation across more than 700 patients was not set up to assess efficacy, but it did show it could provide sufficient protection against SARS-CoV-02.

This, the biotech said, is based on its experience with other vaccines and data from preclinical studies with macaques. “Our findings show that CoronaVac is capable of inducing a quick antibody response within four weeks of immunization by giving two doses of the vaccine at a 14-day interval,” the researchers said in the journal.

This will not create the same excitement as Moderna and Pfizer/BioNTech’s phase 3 top-line peek this month, which showed their vaccines could offer 90%-plus efficacy, though these data still need to be published in full and peer reviewed and were later-stage efforts with different endpoints than the early tests from Sinovac published today.

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The Sinovac tests were done in the early days of the pandemic, in April and May, with later-stage efforts now ongoing; the trial was also assessing what dose to use in these tests, with the biotech finding the 3-μg dose of CoronaVac would be used for phase 3 studies.

Sinovac is already pushing ahead with late-stage trials, although one phase 3 trial of its vaccine was stopped in Brazil this month after reports of a serious safety concern, with one report stating a death is involved but that it was not in the vaccine arm.

Sinovac is also undertaking phase 3 trials in Turkey and Indonesia as well as Brazil; data from these are assessing efficacy and will be the real litmus test for this vaccine.