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Animal studies show Sinovac’s COVID-19 vaccine is protective, does not cause ADE

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Less than one week after entering the clinic, Sinovac became the first company to report animal data supporting its COVID-19 vaccine candidate.

Sinovac Biotech Ltd. (NASDAQ:SVA) has PiCoVacc in a Phase I/II study and expects to start Phase III testing this year.

The Beijing-based company reported the rodent and non-human primate safety and efficacy data supporting PiCoVacc in a preprint posted Sunday to bioRxiv.

On safety, Sinovac showed that the chemically inactivated virus vaccine didn’t cause antibody-dependent enhancement (ADE) in rhesus macaques. The risk of ADE -- a process by which antibodies made in response to vaccination or infection worsen instead of protect against disease -- has been a primary safety concern among vaccine developers (see “Global Regulators’ Report Offers Framework for Data Needed”).

Furthermore, PiCoVacc didn’t induce changes in the levels of inflammatory cytokines or histological signs of pathology organs including heart, kidney, lung, spleen and brain in the primates.

On efficacy, Sinovac showed that mice, rats and rhesus macaques vaccinated with PiCoVacc produced anti-SARS-CoV-2 neutralizing antibody titers similar to recovered COVID-19 patients’ titers.

In a more definitive sign of protection, intratracheally infected macaques that had been immunized three times had lower levels of viral RNA in throat and anal swabs and lung tissue than unvaccinated macaques. The vaccinated macaques furthermore exhibited only small histological signs of lung damage whereas the control animals had developed severe interstitial pneumonia.

Antibodies from the rodents neutralized COVID-19 isolates from hospitalized patients in China, Italy, Switzerland, the U.K. and Spain, suggesting that the vaccine could be effective against a wide variety of SARS-CoV-2 strains.

Sinovac also plans to evaluate whether to advance PiCoVacc in combination with the CpG 1018 adjuvant from Dynavax Technologies Corp. (NASDAQ:DVAX) into the clinic.

According to BioCentury’s COVID-19 Resource Center, at least 70 COVID-19 vaccines are in development; nine are in the clinic.

Further analysis of the coronavirus crisis can be found at https://www.biocentury.com/coronavirus.

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