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SINGAPORE / BEIJING (November 18): Sinovac Biotech’s experimental COVID-19 vaccine, CoronaVac, triggered a rapid immune response, but the level of antibodies produced was lower than in people who had recovered from the disease, the researchers showed. preliminary test results on Wednesday.
While the early to mid-stage trials were not designed to evaluate the efficacy of CoronaVac, the researchers said it could provide sufficient protection, based on their experience with other vaccines and data from preclinical studies with macaques.
The study comes on the heels of upbeat news this month from US drug makers Pfizer and Moderna, as well as Russia, which showed their experimental vaccines were more than 90% effective according to interim data from large late-stage trials.
CoronaVac and four other experimental vaccines developed in China are currently in late-stage trials to determine their effectiveness in preventing COVID-19.
Sinovac’s findings, published in a peer-reviewed article in the medical journal The Lancet Infectious Diseases, come from the results of phase I and phase II clinical trials in China with more than 700 participants.
“Our findings show that CoronaVac is able to induce a rapid antibody response within four weeks after immunization by administering two doses of the vaccine at a 14-day interval,” said Zhu Fengcai, one of the authors of the paper.
“We believe this makes the vaccine suitable for emergency use during the pandemic,” Zhu said in a statement published alongside the document.
The researchers said findings from large late-stage studies or Phase III trials would be crucial in determining whether the immune response generated by CoronaVac was sufficient to protect people from coronavirus infection.
Sinovac is currently running three phase III trials in Indonesia, Brazil, and Turkey.
The results should be interpreted with caution until the Phase III results are published, said Naor Bar-Zeev, a Johns Hopkins University professor who was not involved in the study.
“But even then, after the completion of the Phase III trial and after licensing, we should be prudently cautious,” he said.
‘Attractive option’
CoronaVac is one of three experimental COVID-19 vaccines that China has been using to inoculate hundreds of thousands of people under an emergency use program.
The other two vaccines in China’s emergency program, both developed by institutes linked to Sinopharm, and another vaccine from CanSino Biologics, were also shown to be safe and triggered immune responses in early and mid-stage trials, peer-reviewed articles show. .
Gang Zeng, a Sinovac researcher who was involved in the CoronaVac study, said the vaccine could be an attractive option because it can be stored at normal refrigerator temperatures of 2 to 8 degrees Celsius (36 ° -46 ° F) and can remain stable. for up to three years.
“It would offer some advantages for distribution in regions where access to refrigeration is challenging,” said the author.
The vaccines developed by Pfizer / BioNTech and Moderna use a new technology called synthetic messenger RNA (mRNA) to activate the immune system against the virus and require much cooler storage.
Pfizer vaccine should be stored and shipped at -70 ° C, although it can be stored in a regular refrigerator for up to five days, or up to 15 days in a thermal shipping box. The Moderna candidate is expected to be stable at normal refrigerator temperatures for 30 days, but for storage for up to six months it should be kept at -20 ° C.
CoronaVac is also being considered by Brazil and Indonesia for vaccines in the coming months.
Indonesia has requested emergency authorization to start a mass vaccination campaign before the end of the year, and the vaccines produced by Sinovac and Sinopharm of China are expected to be used in the early stages of the campaign.
Brazil’s Sao Paulo also plans to launch CoronaVac starting in January and has reached a supply agreement with Sinovac.
“The excellent safety of CoronaVac, compared to other vaccines in development, generates greater acceptance by the population,” Ricardo Palacios, trial manager of the biomedical center of Brazil’s Butantan Institute, which is testing CoronaVac, told Reuters.
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