The right dose, immunogenicity, and safety of CoronaVac were evaluated in a randomized, double-blind, placebo-controlled study.
An inactivated SARS-CoV-2 vaccine from China’s Sinovac has successfully completed phase II clinical trials: the authors claim that their medicine CoronaVac is well for the body system and there are no dosage-related safety concerns. The research preprint was published on medRxiv.
The vaccine was administered intramuscularly to healthy adults aged 18-59 years according to the scheme of two injections – on the first and on the 14th day – at a dose of both 3 mg / 0.5 ml and 6 mg / 0.5 ml.
CoronaVac showed good immunogenicity even at 3 mg: 92.4% of the test subjects had neutralizing antibodies after 14 days, and 97.4% – on day 28. Their levels, however, declined significantly with age. This indicates that the old people may require an increased dose or additional dose, the authors noted.
Data about “side effects” were sorted from each vaccination for a week and 28 days. Most of them are mild: there was a pain in the place of injection. There were no difficult cases. The side effect of bad reactions in the 6 mg and 3 mg groups were comparable, indicating a good safety profile.
“Compared to other vaccine candidates, in our case, the incidence of fever in the vaccinated was relatively low,” said experts from Sinovac.
They clarified that in this study, only humoral immunity (antibodies) was assessed, although additional testing of the responses of the T-cell defense mechanism has begun.
Phase II is now also underway on the old people. For Phase III, Beijing developers decided to use a dosage of 3 mg. They will do vaccination for 9000 volunteers in China and Brazil.