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BEIJING: 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, preliminary results of the trial showed Wednesday ( November 18th).
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 percent effective according to interim data from large trials in advanced stage.
READ: Moderna says its vaccine is 94.5% effective in preventing COVID-19
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 1 and phase 2 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.
A man works at the packaging facility of Chinese vaccine manufacturer Sinovac Biotech, developing an experimental vaccine against the coronavirus disease (COVID-19), during a government-organized media tour in Beijing, China on September 24, 2020. (Photo: REUTERS / Thomas Peter)
The researchers said the findings from large late-stage studies or Phase 3 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 3 trials in Indonesia, Brazil and Turkey.
Naor Bar-Zeev of Johns Hopkins University, who was not involved in the study, said 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 licensing, we should be cautious with caution,” 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, according to peer-reviewed articles. .
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 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.
In contrast, 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.
The Pfizer vaccine should be stored and shipped at -70 degrees Celsius, 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 degrees Celsius.
READ: Pfizer will begin a pilot program to deliver its COVID-19 vaccine in 4 US states.
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 China’s Sinovac and Sinopharm are expected to be used in the early stages of the campaign.
Brazil’s Sao Paulo also plans to implement CoronaVac starting in January and has agreed a supply agreement with Sinovac.
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