TOKYO: Japanese public health experts warn of a possible outbreak of the XE subvariant of the omicron coronavirus variant in the country, where signs of a potential seventh COVID-19 wave are emerging.

The health ministry said Monday that it has detected the XE strain for the first time in Japan, in a woman in her 30s who arrived in the country from the United States on March 26. She was asymptomatic upon arrival.

XE is a mix of two earlier omicron subvariants, BA.1 and BA.2. It was first identified in mid-January in Britain, where about 1,100 infection cases had been reported as of April 5, according to Japan’s National Institute of Infectious Diseases.

In Britain, the XE subvariant accounts for less than 1 pct of total COVID-19 cases, according to the institute. XE cases have also been detected in countries such as the United States and Denmark.

The XE subvariant is believed to be about 12.6 pct more transmissible than BA.2, which itself is more contagious than BA.1

Vaccines and neutralizing antibodies provide similar levels of protection against XE as they do against BA.2 because they have the same spike proteins. The XE’s risk of causing severe symptoms is unknown.

A health ministry panel of experts said Wednesday that it is necessary to keep a close watch on the XE subvariant through genome sequencing.

The omicron variant is reportedly less severe but often causes severe symptoms, said Norio Sugaya, professor at Keio University who is an expert on infectious diseases. “XE is believed to be more transmissible than BA.2 and is very alarming,” he said.

JIJI Press