Results of an early-phase randomized clinical trial of a Chinese vaccine candidate based on the inactivated complete SARS-CoV-2 virus (CoronaVac) show that the formulation appears safe and induces an antibody response in healthcare volunteers aged 18 to 59 years. .
The results, published Tuesday in The Lancet Infectious Diseases Journal, add to the number of candidate vaccines tested that have been found to be safe. The Chinese trial involved more than 700 volunteers recruited from China between April 16 and May 5.
“The vaccine appeared to be safe and well tolerated at all doses tested. The most common side effect reported was pain at the injection site. Within 14 days of the final dose, the study detected robust antibody responses after two injections of the candidate vaccine were given 14 days apart, even at the lowest dose tested (3 µg), ”said the magazine.
The results showed that the vaccine-induced antibody levels were lower than those seen in people infected and recovered from Covid-19, but the researchers said they still hope the vaccine can provide protection against the virus.
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Antibody responses could be induced within 28 days of the first immunization by administering two doses of the candidate vaccine 14 days apart, the results showed. The study also identified the optimal dose to generate the highest antibody responses, taking into account side effects and production capacity: 3 µg.
Fengcai Zhu, joint lead author of the study, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China, said: “Our findings show that CoronaVac is capable of inducing a rapid antibody response within four weeks after immunization by administering two doses of the vaccine in an interval of 14 days ”.
“We believe this makes the vaccine suitable for emergency use during the pandemic. In the long term, when the risk of Covid-19 is lower, our findings suggest that giving two doses one month apart, rather than two weeks apart, might be more appropriate to induce stronger and potentially more immune responses. durable. However, more studies are needed to verify how long the antibody response remains after any of the vaccination programs. “
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CoronaVac is a chemically inactivated whole virus vaccine based on a strain of SARS-CoV-2 that was originally isolated from a patient in China. The phase 1/2 clinical trial was conducted in Suining County of Jiangsu Province in China.
In a linked comment, Johns Hopkins University’s Naor Bar-Zeev, who was not involved in the study, said: “Like all phase 2 trials, the results should be interpreted with caution until the phase 3 results are published. But even then, after the completion of phase 3 of the trial and after the license, we must be cautious with caution. “
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