Sinovac’s COVID-19 Vaccine Induces Rapid Immune Response: Study

SINGAPORE / BEIJING (Reuters) – Sinovac Biotech CoronaVac’s investigational COVID-19 vaccine triggered a rapid immune response, but the level of antibodies produced was lower than in people who recovered from the disease, the results showed preliminary tests Wednesday.

Although early-to-mid-stage trials were not designed to assess the effectiveness of CoronaVac, the researchers said it could provide sufficient protection, based on their experience with other vaccines and data. preclinical studies on macaques.

The study follows on the heels of optimistic news this month from US drugmakers Pfizer and Moderna as well as Russia which showed their experimental vaccines to be over 90% effective based on provisional data. from large-scale end-stage trials.

CoronaVac and four other investigational vaccines developed in China are currently in late 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 involving more than 700 participants.

“Our results show that CoronaVac is able to induce a rapid antibody response within four weeks of vaccination by administering two doses of the vaccine at an interval of 14 days,” said Zhu Fengcai, one of the authors of the article. .

“We believe this makes the vaccine suitable for emergency use during the pandemic,” Zhu said in a statement released alongside the document.

The researchers said the results of 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 against coronavirus infection.

Sinovac is currently conducting three Phase III trials in Indonesia, Brazil and Turkey.

The results should be interpreted with caution until the results of Phase III are published, said Naor Bar-Zeev, a professor at Johns Hopkins University who was not involved in the study.

“But even then, after the phase III trial is over and after approval, we have to be careful,” he said.

‘ATTRACTIVE OPTION’

CoronaVac is one of three experimental COVID-19 vaccines that China is using to inoculate hundreds of thousands of people as part of an emergency use program.

The two other vaccines from the Chinese emergency program, both developed by institutes linked to Sinopharm, and another vaccine from CanSino Biologics, have also been shown to be safe and trigger immune responses in early and intermediate trials, according to reports. peer-reviewed articles.

Gang Zeng, a Sinovac researcher involved in the CoronaVac study, said the vaccine could be an attractive option because it can be stored at normal refrigerator temperatures of 2-8 degrees Celsius (36 ° -46 ° F) and can remain stable for up to three years.

“(This) would provide some benefits for distribution in areas where access to refrigeration is difficult,” the author said.

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 colder storage.

Pfizer vaccine should be stored and transported at -70 ° C although it can be stored in a normal refrigerator for up to five days, or up to 15 days in a thermal shipping box. Moderna’s candidate should be stable at normal refrigerator temperatures for 30 days, but for storage up to six months it should be stored at -20 ° C.

CoronaVac is also being considered by Brazil and Indonesia for inoculations in the coming months.

Indonesia has requested emergency clearance to launch a mass vaccination campaign by the end of the year, and vaccines produced by China’s Sinovac and Sinopharm are expected to be used in the early stages of the campaign.

The Brazilian Sao Paulo also plans to deploy CoronaVac as early as January and has entered into a supply agreement with Sinovac.

“The excellent safety of CoronaVac, compared to other vaccines in development, allows for better acceptance by the population,” Ricardo Palacios, director of the trial at the Biomedical Center at the Butantan Institute, told Reuters. Brazil, which is testing CoronaVac.