A local resident gets a nucleic acid test at a local health service station in Guangzhou, South China's Guangdong Province, on May 30. Photo: VCG

Mutated virus strains first identified in India triggered community transmission for the first time in China in recent COVID-19 infections in South China's Guangzhou. The city expanded areas subjected to stay-at-home orders on Thursday, locking down two more streets in Liwan district covering nearly 140,000 residents.  

Guangzhou discovered six new confirmed COVID-19 cases and one asymptomatic case on Thursday, bringing the total number of confirmed cases to 64 and silent infections to 13 in the recent cluster of infections from May 21 to Thursday. All locally-transmitted cases were treated at Guangzhou Eighth People's Hospital under Guangzhou Medical University, a designated COVID-19 hospital in the city. 

Cai Weiping, an infectious disease center doctor of the hospital, told China Central Television on Thursday that the recent COVID-19 infections in Guangzhou were caused by mutated virus strains first identified in India, which have a shorter incubation period and higher viral load and can spread faster. 

He said that this is also the first time that the mutated virus strains first identified in India caused community transmission in China. 

Cai said that a major feature of the mutated strains is that they have an extremely high viral load found in nucleic acid tests among patients, and the amount of the viral load found in patients this time was double that of last year's patients.

He said that the average incubation period was around 5.9 days last year but this time it was only 3.2 days. 

The variant spreading in Guangzhou has an incubation period of 3.2 days but only 77 infection cases were discovered in the two weeks. Based on this, we can say that the transmissibility and pathogenicity is not as strong as that spread last June in the Xinfadi market in Beijing, Yang Zhanqiu, a virologist from Wuhan University, told the Global Times on Friday. 

An outbreak occurred in the Xinfadi market in Beijing from June 11 to July 31, 2020. The variant caused this outbreak was found to come from Europe, but older than Europe's most recent virus. According to official data, in the first two weeks of the outbreak, 269 confirmed cases and 22 silent virus carriers were discovered.    

The measures the Guangdong authority is taking are also stricter than those implemented during the Xinfadi epidemic. This can serve as a guide for India to control the variant, as the current low transmission of the variant in Guangzhou communities shows that India can put the transmission of the variant under control quickly as long as they take measures as strict as Guangzhou, Yang noted.

Yang estimated that the epidemic in Guangzhou would not become more serious under such strict measures.  

India recorded 132,364 new cases with 2,713 deaths on Thursday, The Hindustan Times reported Friday.  

On Friday, several Guangzhou hospitals including the First Affiliated Hospital Of Guangzhou Medical University suspended their outpatient services citing needs of epidemic control and prevention. 

Guangzhou government on Thursday announced that two more streets of Liwan district were placed under lockdown, which covered nearly 140,000 residents. Residents in the involved areas are asked to strictly follow st