Adopting strict control measures to effectively cut off COVID-19 transmission routes is of great importance, according to China's leading epidemiologist.

China is focusing on the source of infection, the route of transmission and vulnerable groups in epidemic prevention and control efforts, Liang Wannian, head of the COVID-19 response expert panel under the National Health Commission said in a recent group interview.

Liang explained the measures and strategies will be constantly adjusted to the fluid situation under the "dynamic zero COVID-19" policy.

He stressed the key of "dynamic zero COVID-19" should be to quickly spot new cases and identify the source of the virus, then take swift measures to cut off the spread.

"The essence is swift and precise responses," said Liang. He said the public health system must stay vigilant on monitoring sources of the virus and related symptoms, and containing the spread in as limited an area as possible.

Liang said China still needs to boost its vaccination rate, especially among the elderly as they have a weaker immunity against the virus.

"It is clear that once we loosen up the prevention measures, the wide spread of the virus could cause a massive number of severe cases, even death among the elderly," said Liang. "It'll be a disaster for the country."

A surge of severe cases could also crash the medical system, he added.

In the future, control measures may be lessened if vaccines can better protect vulnerable people, effective drugs are available, or infection sources can be detected more quickly and accurately, he added.

(With input from Xinhua)