Photo: courtesy of Sinovac

In the race against time with the more infectious and deadly Delta variant, Chinese vaccine developers and scientists are bringing about effective solutions including special Delta variant-targeting vaccines and new technology paths to deal with the new COVID-19 menace in steady and cautious steps.  

One of the country's vaccine developers Sinovac plans to submit clinical application materials for its inactivated vaccine especially for the Delta variant to authorities in the third season this year, Gao Qiang, general manager with the Beijing-based Sinovac Life Sciences Corp, revealed. 

Sinovac has completed preclinical research on the Delta variant as well as the Gama variant, and it will submit application materials for clinical research in the near future, Gao said in a recent interview published on Sunday, noting that protection against the Delta strain by the new vaccine is expected to be no less than existing vaccines, and it will take a two- or three-shot path to enhance immunity.

When asked if there is a timetable for the rollout of the vaccine, Gao revealed that matters to do with R&D shall follow the country's regulation, and clinical research will be initiated after attaining approvals, results of which will determine if such vaccines can go on the market. 

Tao Lina, a Shanghai-based vaccine expert, told the Global Times on Sunday that the clinical research stage for the specific variant-targeting vaccine might be shorter than the same stages of current vaccines, and six months would be more than sufficient to conclude it. 

Gao also said the firm has completed study on the booster shot of the COVID-19 vaccine, known as the CoronaVac, and the inoculation of the third shot is as safe as the first two, which could significantly enhance levels of neutralizing antibody within a week.

Two shots of the current Sinovac inactivated vaccine, judging from the situations in regions including South China's Guangdong Province and Nanjing, East China's Jiangsu Province, can still remarkably reduce the risks of developing symptoms and critical illness from the Delta variant infection.

Scientists with the China Academy of Sciences are expected to publish their findings on the progress soon, Gao said, adding that research on the booster dose in immunization has been carried out in China, Turkey, Chile and other countries, and results will soon be obtained.

But Shao Yiming, a leading physician and immunologist from the Chinese Center for Disease Control and Prevention (China CDC), told the Global Times on Sunday that there is no plan yet to administrate a booster shot for everyone.

As a single-stranded RNA virus, the novel coronavirus frequently mutates due to its biological characteristics. The current research and observations show that although the current vaccines may have a reduced protection effect against the Delta variant, they still have good preventive and protective effect, the Sinovac general manager said.

Meanwhile, Chen Bin, spokesperson with the health commission in Guangzhou, Guangdong, announced during a press conference on Friday that adult residents in the city can start making reservations to take the Chinese hamster ovary (CHO) cell vaccine, or commonly known as the three-shot COVID-19 vaccine. 

Jointly developed by experts from China's CDC and the Chinese Academy of Sciences, including the CDC director Gao Fu, the neutralizing antibody level produced by the vaccine was comparable to that of other recombinant protein vaccines and mRNA vaccines currently used worldwide, meeting advanced international standards, according to a statement by the CAS in March.

Citing a preprinted paper by Gao Fu, the commission said the CHO cell vaccine can reserve its neutralizing effect against the Delta variant. 

"We have evaluated the neutralizing effect of the antibody serum triggered by the vaccine against four variants of concern [Alpha, Beta, Gamma and Delta] and other three interesting ones [Epsilon, Eta and Kappa]. By simulating virus particles, it was found that the antibody serum retained most of the neutralizing activity against these mutant strains," reads the paper. 

On February 22, the Uzbek legislature approved the Emergency Use Authorization (EUA) for the vaccine in Uzbekistan. The vaccine was approved for use on March 1. Uzbekistan rates the vaccine as one of the safest and most effective in the world.

Tao also suggested that the inhaled vaccine jointly developed by prominent Chinese vaccine developer Chen Wei and Chinese biotech company, CanSino Biologics Inc, would also be effective against the Delta variant. 

Compared with traditional shots, the inhaled ones can work better to curb the variant which is twice as contagious as the previous variant at the respiratory tract and mucus system right away, Tao explained.