Dr Zhang Wenhong, head of Shanghai's COVID-19 treatment team and director of the National Center for Infectious Diseases.

Omicron is not merely a "big flu," but requires a strong immune barrier and medical resources to resist its threats, Shanghai's top coronavirus expert has said.

There is no scientific basis to claim that the Omicron variant of COVID-19 could only lead to severe influenza, said Dr Zhang Wenhong, head of Shanghai's COVID-19 treatment team.

"Without sufficient medical resource, Omicron will bite," Zhang, who is also the director of the National Center for Infectious Diseases, told a local forum on Saturday.

Western media has reported that the Omicron variant, which spreads faster than its predecessor Delta, is less likely to cause serious illness.

They have criticized China's "Zero COVID" strategy, which has actually become one of the world's most effective and successful prevention measures against the spread of SARS-CoV-2.

Early studies showed that the Omicron coronavirus variant affected the upper respiratory tract, causing milder symptoms than previous variants.

"This suggests a virus that is more transmissible, but less dangerous," the Economist reported.

However, Zhang said through his research on the chest radiographies of multiple patients, Omicron is the "winner of the fight with the human immune system."

North China's Tianjin starts citywide nucleic acid testing after 20 people tested positive for COVID-19.

Vaccination and medical resources

Vaccination and strong medical resources remain the best solutions to resist Omicron, said Zhang.

According to WHO data, some 128 countries had reported cases of the Omicron variant as of December 29, 2021. North China's Tianjin, a municipality that neighbors Beijing, has reported two locally-confirmed cases infected with the VOC/Omicron variant.

"Vaccination still plays an inevitable role during the fight against the pandemic," said Zhang. "Without an active vaccination and strong immune barrier, the world will return to the 1918 flu pandemic."

Some 50 million died worldwide in the flu pandemic – sometimes inaccurately referred to as the "Spanish flu" – making it the deadliest event in human history. That far exceeds global COVID-19 deaths so far – around 5.4 million.

Zhang said though vaccines failed to completely stop the spread of COVID-19, they've largely reduced the virulence as well as the death toll.

The United Kingdom reports more than 200,000 confirmed cases every day, but the death rate remains at the same level, thanks to the 80 percent vaccination rate and the fact that over half of the population has taken booster shots, according to Zhang.

Most healthy young people in the countries with high vaccination rates, such as the United States, Singapore and Israel, are expected to get through the fierce round of pandemic caused by Omicron, Zhang said.

"The world will be restored only with strong immune barriers and extremely low death rate," he said. "We've seen the light of dawn after the long dark night."

Residents in Tianjin begin receiving nucleic acid testing for COVID-19.