The Omicron variant of the COVID-19 virus spreads faster and in a more covert way than the previously dominant Delta variant but still possess some level of lethality, renowned Shanghai doctor Zhang Wenhong wrote on his Sina Weibo account on Thursday.

Zhang, the leader of the Shanghai team of experts in the clinical treatment of novel coronavirus pneumonia cases, stated that he came to such a conclusion after his team looked into all the cases currently receiving medical treatment in Shanghai.

"The current number of imported COVID-19 cases in Shanghai is at a record high," wrote Zhang, who is also the director of the infectious diseases department at Huashan Hospital Affiliated with Fudan University.

The Shanghai government said on Thursday that there are presently 361 imported cases being treated in the municipality. The number of imported cases reported in Shanghai has been in the double digits every day over the past 10 days. Shanghai reported 31 imported cases on Wednesday.

"Omicron still poses a high risk to public health globally and humans are currently at the most difficult time of our fight with it," wrote Zhang.

"Despite indications that this variant causes a lower severity of illness, Omicron spreads faster in communities and leads to a surge in the number of hospitalized cases. This will add burden to health systems and will be dangerous for countries with limited medical resources."

Data has shown that vaccines are less effective against Omicron in terms of reducing infection, symptoms, and hospitalized cases, according to Zhang.

"Meanwhile, there is evidence that shows that a booster shot can increase vaccine efficacy and maintain protection against severe cases," he wrote.

Zhang also pointed out that there are signs that show that the situation is looking up.

"China's best strategy at this time being is to continue strengthening vaccination and public health prevention and control as this would allow us to gradually resume a normal life," he wrote.