China’s CanSino Biologics will be starting clinical trials for a Covid-19 vaccine that is administered through inhalation next week, the company’s co-founder and Chief Executive Xuefeng Yu told CNBC on Sunday.

Such a vaccine could be more effective than those injected given that the coronavirus enters the human body through the airways, Yu told CNBC’s Arjun Kharpal at the Boao Forum for Asia on the island of Hainan, China.

CanSinoBIO is jointly developing the inhalation vaccine with the Beijing Institute of Biotechnology. To be clear, the company’s Adenovirus Type 5 Vector vaccine — or Ad5-nCoV — administered by injection was already approved for use in China and several other countries.

Yu explained that theoretically, an inhaled vaccine could provide additional protection by activating antibodies or T cells — white blood cells that are vital to the immune system — in the airways.

If that protection layer fails and the virus travels deeper into the body, other parts of the immune system could still fight the Covid virus, added Yu.

“So you add more layers — makes sense, right? So that’s why we’re going through the mucosal route,” he said.

The CEO said the company has used the same concept to develop an inhalation vaccine for tuberculosis or TB. Trials conducted in Canada showed that the inhaled dosage for the TB vaccine needed to provide protection is “much, much less than the actual injection,” he said.

CanSinoBIO’s single-dose injected Covid vaccine has been approved for use in several countries including China, Pakistan, Mexico and Hungary.

The company said interim data from phase three clinical trials overseas showed its vaccine was 68.83% effective at preventing symptomatic Covid-19 disease two weeks after one injection, while the rate fell to 65.28% after four weeks, reported Reuters.

Yu said the company has studied adding a booster shot six months after the first injection, which managed to improve the immune response to the coronavirus.  

“That’s also indicating that our vaccine could be boosted — whether it’s being mixed with others or do it our own, I think that needs truly a scientific study. We need to actually have data to demonstrate which way could be better,” said the CEO.

Earlier this month, the director of the Chinese Center for Disease Control said the country was considering giving people different Covid shots to boost vaccine efficacy.

Reuters reported on Monday that Chinese researchers are testing mixing Covid vaccines developed by CanSinoBIO and a unit of Chongqing Zhifei Biological Products. The trial, under way in the eastern city of Nanjing, is expected to involve 120 participants, said the report.

China was the first country to report cases of Covid-19 in late 2019 and appears to have largely contained the outbreak. The country has said it aims to vaccinate 40% of its population by June.