Explainer: Why many infections asymptomatic in China's latest COVID-19 flare-ups?

Special: Battle Against Novel Coronavirus

Shanghai, China's economic hub with a population of more than 24.87 million, is all geared up to deal with a flare-up of COVID-19 infections.

People who follow the daily tally of infections in the Chinese mainland are hard to miss a new trend: the overwhelming majority of new local infections are asymptomatic.

After logging four-digit figures for more than 10 days, the daily caseload of local infections showing no symptoms hit a record high of 7,090 on Tuesday, according to statistics by the National Health Commission (NHC).

A leading Chinese epidemiologist has explained why. Properties of the spreading Omicron variant, timely screenings and high vaccination rates are contributing factors to the high proportion of asymptomatic infections during the latest COVID-19 flare-up, said Zhang Boli, academician with the Chinese Academy of Engineering.

"As it becomes more contagious, the Omicron variant is less lethal," said Zhang.

But this does not mean Omicron is a virus people can take lightly, Zhang added, noting that it is still dangerous to the elderly and people living with underlying health problems among other vulnerable groups.

The NHC recently updated the protocols for diagnosis and treatment of COVID-19 patients, saying asymptomatic cases and those with mild symptoms will be treated in designated quarantine facilities instead of hospitals.

Chinese patent medicine has been used as part of a preventive treatment for asymptomatic cases, according to Zhang.

The large number of asymptomatic cases is also a result of early detection with rapid screenings, as well as mass vaccination of the population, he noted.

Latest NHC statistics showed that nearly 88 percent of the total population in the Chinese mainland had been fully vaccinated against COVID-19 by March 21 and that over 659 million had received a booster shot.

Noting that asymptomatic cases easily cause the spread of the virus by stealth, Zhang called for faster moves of epidemiological investigation and source tracing so as to stem virus transmission.

Despite recent resurgences of the epidemic in multiple locations including Shanghai, Jilin and Shenzhen, only less than 0.1 percent of the infections were in a severe or critical condition, according to the NHC.

Swift response, mass screening and large-scale vaccination, also features of China's dynamic zero-COVID policy, have ensured life and production across the country mostly unscathed over the past two-plus years.

China is still one of the countries which successfully keep COVID-19 under control. Sticking to a dynamic zero-COVID policy, the country has reined in past rounds of epidemic rebound, including that of last year in Tianjin and Xi'an, in a short period of time.

Had it not been for China's manufacturing capacity and continuous flow of commodities, shortages of goods would have bitten into essentials, nudging up retail prices and increasing inflation, thus impeding the already shaky global economic recovery.

With extensive experience in fighting the virus and an approach proven effective by reality, China is continuing putting people's lives first and sparing no efforts to put out the flare-ups as soon as possible.