China detects 18 cases of double mutant variant from India

China has confirmed at least 18 cases of the "double mutant" coronavirus variant circulating in India, including in three Chinese nationals who worked near New Delhi and returned home last month.

The Chinese Center for Disease Control and Prevention (CDC) told state media that more Covid-19 cases imported from India were feared to be found in China, but they were unlikely to trigger cluster infections because of the country's strict entry and screening rules.

A publication from the organisation, CDC Weekly, reported that recently three Chinese nationals tested positive after they returned to the southwest Chinese city of Chongqing after returning from India via Kathmandu.

An epidemiological investigation revealed that the three patients, working at a mobile phone company based in Noida, travelled to New Delhi in a chartered car on April 19 before flying to Kathmandu with protective clothes, N95 respirators, goggles and gloves later that day.

"They stayed in a hotel in Nepal for two days and then flew to southwest China's Chongqing on April 21 and immediately tested positive for Covid-19 after landing in Chongqing," the CDC Weekly report said.

Tests detected coronavirus infections that matched the Indian B.1.617.2 variants, the CDC field notes said, "supporting [the conclusion] that the Covid-19 infection on these three patients probably occurred in India".

The three patients were found Covid-19 positive last month, but the news was reported by state media only on Wednesday – the last day of the five-day Labour Day holidays when hundreds of millions of domestic tourists travelled across the country.

According to a Newsweek report on China's Weibo microblogging service, a hashtag reading "three returning citizens suspected of contracting a virus variant in India" had been read 220 million times at the time of writing.

Many have called for stricter tracking and quarantining for those coming to China from India.

Commercial and special flights between India and China have been banned since last year.

South China's Zhejiang province and Shanghai have also reported imported cases and asymptomatic cases from India.

At least one among the 18 infected persons is an Indian national, the tabloid Global Times reported on Tuesday.

"One asymptomatic case involved an Indian man who landed in Shanghai from Niger via Paris, and he then went to Zhejiang's Yiwu on April 30 after quarantine, and tested positive on Saturday," the Global Times report said.

The Covid-19 strain prevalent in India has been detected in "some cities in my country, and everyone is very concerned," Wu Zunyou, the CDC's chief epidemiologist, had said last Thursday.

Wu did not specify in which cities the cases were detected.

China's national health commission (NHC) on Wednesday said the country had added seven new imported Covid-19 cases in the last 24 hours.

China has reported a total of 90,721 Covid-19 cases and 4,636 deaths since the start of the pandemic, with the last death recorded this January.