By Justin Kim, Edited by Brittany Nguyen & Sami Morse
In the fight to curb the SARS-CoV-2 pandemic, the private Chinese company Sinovac Biotech is developing a vaccine, called Coronavac, that has reached phase 3 clinical trials.
This vaccine is inactivated, meaning researchers develop it by growing the virus in culture, and killing it with heat or chemicals. After this inactivation step, scientists may choose to isolate a specific part of the virus for their vaccination or simply use the entire killed virus. Injection of the resulting product into patients with some inflammatory factors to jumpstart the immune system will, if the vaccine was developed successfully, elicit long-lived immunity against the virus in question. For their candidate, Sinovac has opted to use the entire SARS-CoV-2 virus, and will isolate strains from each country to personalize their vaccine.
In their combined phase 2 & 3 trial, Sinovac investigated a 3 μg/0.5 mL and a 6 μg/0.5 mL dose on two and three week administration schedules, showing promising results. Testing on 743 volunteers, researchers found the vaccine safe and immunogenic. There were zero cases of severe reactions to Coronavac, with the most common symptom being moderate pain at the injection site. Researchers found that the lower dose, three-week administration schedule was most effective, eliciting antibodies in 97.4% of patients in that group.
As discussed in our post regarding Sinopharm’s candidate, there are some risks associated with using an inactivated virus. Namely, it may not produce as robust of a response as other candidates and its required two-dose administration schedule lowers compliance and increases contacts with vaccine administrators.
Although in the midst of phase 3 clinical trials, the Chinese government has approved the vaccine for emergency use, and it has been given to hospital personnel and other high risk groups. Phase 3 trials are underway in Brazil, Indonesia, and Turkey. While we await results from their phase 3 trials, Sinovac is gearing up to produce 300 million doses per year and Sinovac’s CEO hopes to distribute the vaccine in early 2021.
Results from ongoing research and the current understanding of COVID-19 are constantly evolving. This post contains information that was last updated on October 30, 2020.