Residents wait to take nucleic acid tests at a community in Pudong New Area of east China's Shanghai, April 4, 2022. Photo: Xinhua

The number of Shanghai's daily new COVID-19 cases may peak this week and the fresh wave may finish as early as the end of next month, experts said, although China's financial hub reported a record high number of daily new infections on Thursday, bringing the total infections in Shanghai to more than 250,000 since March. 

Shanghai reported 27,719 new infections on Thursday, a new record high for daily cases, and 26,748 were discovered in closed-loop areas and quarantine facilities.  

Compared with the new cases reported on Wednesday, although the total number of infections reported on Thursday was higher, the number of silent carriers discovered in communities on Thursday slightly decreased. 

The number of new cases reported at the community level has been decreasing in Shanghai as most new cases are found in closed-loop areas or in quarantine facilities, which shows that the strict lockdown and preventive measures are working, and that's a positive sign, Chen Xi, an associate professor of public health at Yale University, told the Global Times on Thursday. 

Multiple rounds of nucleic acid testing will find more new cases, Chen said, noting that as more tests are done, more cases will be screened out. If Shanghai can see a continuous drop in community infections, the number of daily new cases will reach an inflexion point, Chen said. 

A model developed by Yao Maosheng, a professor at the College of Environmental Sciences and Engineering at Peking University, who has closely followed the COVID-19 pandemic, showed that Shanghai's COVID-19 outbreak is expected to peak in daily new cases this week.

According to his model, the daily new cases in Shanghai may fall below 100 in mid-June when the outbreak is expected to be well under control. The total number of infections including those confirmed and asymptomatic in Shanghai is likely to reach 650,000-700,000 by the middle of June, Yao told the Global Times on Thursday.

Yao said the current epidemic control measures have greatly slowed down the transmission speed in Shanghai, as the number of daily new cases could have reached more than 200,000 if no timely controls had been enacted.

Another epidemic prediction team led by Huang Senzhong, a professor at Nankai University's Research Institute of Public Health, estimated on Wednesday that Shanghai's epidemic may end by the end of May, although there are still great uncertainties in the development of the outbreak, according to the website of the institute. 

According to the Nankai team, the number of daily new cases may peak this week at about 22,618 to 29,087. 

Although Shanghai is preparing to witness a peak in daily new cases, analysts stressed that Shanghai's control measures cannot be relaxed - instead, these measures need to be tightened and optimized.  

Wu Huanyu, deputy director at the Shanghai Center for Disease Control and Prevention, said at Thursday's media briefing that goods and packages in transit may be contaminated, and infection through contact with contaminated goods cannot be ruled out.

On Wednesday, after two cities in North China's Shanxi Province reported positive cases involving eight deliverymen, some cities in the province suspended delivery services.   

Some Shanghai communities have also strengthened management of online purchases.  

"Our community doesn't encourage us to participate in online group buying without legal channels as contaminated goods could also be a source to spread the virus," a 41-year-old resident in Jing'an district of Shanghai told the Global Times on Thursday. 

When commodities are delivered at the entrance of the residential community, we will disinfect them all before sending them to each home, a 28-year-old volunteer living in Xuhui district, who works about four hours a day to help deliver goods, told the Global Times.

The city also needs more testing within communities, and Wu said that family transmission is the main transmission route. When one family member is infected, the rest may also be infected, but due to the incubation period of the Omicron variant, which is about 3 to 5 days, they may test positive some time later, he said.

In Shanghai, only the antigen testing kits of those who tested positive have been collected and treated as medical waste. Antigen testing kits of those who have tested negative are sorted as dry waste rather than medical waste in Shanghai,which may pose further risks of the spread of the virus, a Beijing-based immunologist who requested anonymity told the Global Times on Thursday.

The immunologist said considering the incidence of false-negative results in antigen testing, some testing kits of those who tested false-negative may contaminate the environment and then infect people, noting that all testing kits should be sorted as medical waste. 

Shanghai is entering the rainy reason, when the coronavirus can survive longer and spread more easily through contaminated sewage, so the medical waste of Shanghai's makeshift hospitals and designated COVID-19 hospitals have to be handled with special care, he said.