Chinese epidemiologist Chung Nam Son predicted Covid-19 "will weaken from June", but warned countries should make more efforts to prevent the spread.

According to Chung, although the anti-nCoV effort has shown positive results, China still needs to tighten control to prevent new cases from foreign countries from entering the country.

"Most foreign infections are asymptomatic, half of them have no fever, similar to the early stage of Wuhan," Chung told reporters in Beijing today. "This shows that other countries have not done enough to stop the virus."

Out of China's 15 new cases of nCoV on March 12, six were diagnosed from all foreign countries.

In China, Chung was often called the "SARS hero" because he discovered acute respiratory syndrome (SARS) in 2002 and found a treatment. He is also leading an nCoV evaluation board.

China is taking tough measures to prevent the risk of "reinfection" of nCoV from other countries. Mr. Chung supported this response. "We must step up prevention and control as well as increase communication with other countries to protect China from new sources of infection," he said.

Covid-19 originated in Wuhan, China in December 2019, appeared in 125 countries and territories, leaving more than 126,000 people infected, more than 4,600 dead and more than 68,000 people recovered. The World Health Organization (WHO) yesterday declared Covid-19 a pandemic and urged nations to deal aggressively.