It will need at least one or two years for mass vaccination to prevent COVID-19, Zhong Nanshan, a leading respiratory disease expert, said Thursday, and he called on people to take conventional measures to prevent the disease at present.

Zhong, recipient of the Medal of the Republic, made the remarks via video link at the 13th China Bioindustry Convention that was held in Wuhan, capital of Central China's Hubei province, China Youth Daily reported.

China has been working with over 40 countries on vaccine development and has gained approval from countries such as Russia and Brazil to carry out phase 3 trials in the countries, Zhong said, and four vaccines have entered international phase 3 trials.

Zhong also noted that COVID-19 epidemic may continue or even worsen this winter and next spring.

Once infection is detected in an area, joint prevention and control measures in communities, nucleic acid testing for all community residents and quarantine for asymptomatic cases are effective measures to contain the spread, he said.

In particular, asymptomatic cases must be placed strictly under quarantine, as they are highly contagious during the five days before and after they show symptoms, Zhong noted.

Jointly organized by the Hubei provincial government and 20 national-level associations including the Chinese Society of Biotechnology, the 13th China Bioindustry Convention is the highest-level summit on biological industry the nation has held since the outbreak of the COVID-19.

More than 100 advanced anti-virus technologies and products were on display, with the world's first COVID-19 inactivated vaccine and nucleic acid testing kit making an appearance.