Residents in Guangzhou, South China's Guangdong Province undergo nucleic acid tests on May 30. Photo: VCG

Guangzhou, capital of South China's Guangdong Province, which records 90 percent of Chinese mainland's inbound international arrivals every day, is in a race against mutated virus strains from India, which have been found in 26 COVID-19 patients.  

Experts said that the appearance of the strains, which are more contagious and spread faster, to China's southern gate doesn't invalidate China's anti-epidemic policies, but reminds local authorities to act faster and devote more efforts to tracing real sources of infection and plugging loopholes. 

Starting from 10 pm on Monday, passengers leaving Guangzhou must present a negative nucleic acid test result taken within 72 hours, according to a latest notice issued by Guangzhou's COVID-19 epidemic prevention and control office on Sunday.

The province previously weathered six rounds of locally transmitted outbreaks triggered by imported cases. These all had very short transmission chains and one generation of COVID-19 patients - thus, they were contained within a week. However, this wave of resurgence in the province, propelled by the mutated virus from India, has a much longer transmission chain and five generations of individual cases. 

"The rapid spread of the disease and the short intergenerational transmission time is signaling great threats posed by the mutated virus from India to Guangdong, which had been regarded as an exemplary place in handling the epidemic," Zhang Yuexin, a medical expert specializing in anti-epidemic prevention and control, told the Global Times on Sunday. 

This resurgence, which has spread beyond Guangzhou to the neighboring cities of Foshan and Maoming, had involved five local confirmed cases and 21 asymptomatic patients as of Sunday. It started on May 21. 

Guangzhou completed its first round of nucleic acid testing for 2.25 million residents on Saturday, with 20 people found to be infected with COVID-19 as of 2 pm on Sunday, said Chen Bin, a deputy director of Guangzhou Health Commission at a press conference on Sunday.

The results of the detected gene sequencing in all of the infected patients in the latest outbreak were highly homologous, all from variants detected in India, Chen said. 

A 75-year-old female patient, surnamed Guo, living in Guangzhou's Liwan district was the first patient to be detected, but it didn't make her the original source of infection, as local health officials had said she may have become infected due to accidental exposure. 

Liwan issued a stay-at-home order for residents of the five most affected streets. The residents have been asked to stop all activities that are not necessary for daily life. 

The latest outbreak in Guangzhou has more prominent characteristics compared with previous ones - the variant is very infectious and its transmission rate is very high, according to Guangzhou local authorities. 

"The virus can be spread by brief and indirect contact. It can spread among people who are at one meal," said Zhang Zhoubin, a deputy director of Guangzhou Center for Disease Control and Prevention, at a Thursday meeting. 

Wang Guangfa, a respiratory expert at Peking University First Hospital, believes that Guangzhou should continue its current measures, as there is no evidence that these measures were invalid in preventing variants from India.

Guangdong is the province with the largest number of inbound visitors in China since the pandemic began, accounting for 90 percent of the country's inbound international arrivals every day, according to Duan Yufei, director of Health Commission of Guangdong Province. 

In particular, Guangzhou, where one of the world's busiest airports sits, is at the frontline that faces and digests the most pressure of the prevention and control work for imported infections. In 2020, Guangzhou's Baiyun International Airport handled 43.77 million passenger trips, becoming the busiest airport in the world for the year. 

But Wang told the Global Times on Sunday that the epidemic in Guangzhou exposed some difficulties or hidden loopholes in terms of either imported people or items, as no clear source of infection was revealed in clustered cases in Guangzhou.

Wang reminded Guangzhou to "act faster, be more vigilant and devote more effort" to tracing sources of infection to avoid further community transmission and plug unsuspected loopholes in handling imported cases.

Given the rapid spread of the outbreak in Guangdong, triggered by mutated virus strains from India, Zhang urged the public to adopt stricter anti-epidemic rules in daily life, including thorough disinfection and wearing masks properly.

Escalating China's current anti-epidemic policies just to prevent mutated virus strains is not wise and could pose obstacles for normal economic communications when the real source of infections in this wave has not yet been identified, experts said.

Liwan's two neighboring districts Yuexiu and Zhuhai, with populations of 1.2 million and 1.7 million respectively, both started mass nucleic acid testing on Sunday. The testing will last until Tuesday, according to official announcements.