Inactivated SARS-CoV-2 Virus Effective in Immunizing Mice, Rats, and Non-Human Primates; Effective Neutralizing Antibodies Produced, Scientists from Sinovac & Other China-Based Institutions Report in Science; Immunized Macaques Resist Virus Challenge

In an article published online on May 6, 2020 in Science, researchers from Sinovac Biotech in Beijing, China, together with colleagues from other institutions in China, including the Peking Union Medical College, report the successful vaccination of mice, rats, and non-human primates (macques) with a purified, chemically-inactivated form of the SARS-CoV-2 virus (PiCoVacc). The animals all produced SARS-CoV-2-specific neutralizing antibodies. The scientists said that these antibodies neutralized ten representative SARS-CoV-2 strains. The researchers added that three immunizations, using two different doses (3 μg or 6 μg per dose), provided partial or complete protection in macaques against SARS-CoV-2 challenge, respectively, without observable antibody-dependent enhancement of infection. The researchers stated that “these data support clinical development of SARS-CoV-2 vaccines for humans.” In conclusion, the authors wrote the following: “Although it’s still too early to define the best animal model for studying SARS-CoV-2 infections, rhesus macaques that mimic COVID-19-like symptoms after SARS-CoV-2 infection appear promising animal models for studying the disease. We provide evidences for the safety of PiCoVacc in macaques; and did not observe infection enhancement or immunopathological exacerbation in our studies. Our data also demonstrate a complete protection against SARS-CoV-2 challenge with a 6 μg per dose of PiCoVacc in macaques. Collectively, these results suggest a path forward for clinical development of SARS-CoV-2 vaccines for use in humans.