People wearing protective face masks walk on a pedestrian crossing at Tokyo's Shibuya district. Photo: AP

A Chinese virologist said that a novel coronavirus mutation with a variation level exceeding 20 percent may lead to vaccines, current treatments and viral-testing measures becoming ineffective after a recent study in Japan indicated that the virus in the country has mutated into a form with a new genome sequence, which has been spreading in a second COVID-19 spike since mid-June.

The study by Japan's National Institute of Infectious Diseases published on Wednesday found that the European strain of the virus waned in the country in late May, and a mutated version of the virus was later found in Tokyo and soon in other parts of the country. Most of the recently confirmed patients in Japan are believed to have been infected with the virus after mutation, local media reported.

Japan reported 1,565 new cases on Saturday, bringing the total number to 47,464, according to the Xinhua News Agency. 

The country has experienced a COVID-19 epidemic resurgence since the middle of June, with the daily case load exceeding 1,000 in late July and seeing a rising trend. In its first wave of the epidemic which was eased in May, the record was 743 cases in a single day. 

The virus becomes more infectious and transmissible when comparing the two COVID-19 spikes, Yang Zhanqiu, deputy director of the pathogen biology department at Wuhan University, told the Global Times on Sunday. 

"If the virus mutates to a level of more than 20 percent variation, it will significantly affect the effectiveness of testing and vaccines that are in development for COVID-19," said the virologist. 

As of Wednesday, 5,116  patients had been hospitalized in Japan, with more than 1,000 people admitted within the past week, according to the Ministry of Health, Labor and Welfare of the Japanese government in its latest weekly report. 

Global Times