The new version of omicron XE Covid, first discovered in the UK, is expanding to Japan as the number of cases increases

Japan has reported its first case of omicron XE – the first new strain of Covid-19 discovered in the United Kingdom – just like the British examples of subvariant growth.

The XE version was found in a 30-year-old woman who arrived at Narita International Airport from the US on March 26. The woman, whose citizenship was not immediately disclosed, was asymptomatic, the Japanese Ministry of Health said Monday.

According to the latest statistics, the number of cases of the new strain in the UK has almost doubled United Kingdom Health Safety Agency.

As of 5 April, 1,125 XE cases have been identified in the United Kingdom, compared with 637 on 25 March. The earliest confirmed case has a sample date of 19 January this year, indicating that it could be in circulation in the population for several months.

XE has since been discovered in Thailand, India in Israel. It is speculated that the latter Israeli cases may have developed independently. The US has not yet reported any cases of XE.

Such recombinants are not uncommon, as they have occurred several times during the course coronavirus pandemic. However, health experts say it is too early to conclude on the severity or ability of the new sub-variant to avoid vaccines.

“We continue to monitor cases of recombinant version XE in the UK, which currently accounts for a very small proportion of cases,” said Meera Chand, director of clinical and emerging infections at UKHSA.

On Sunday, the United Kingdom reported 41,469 new cases of Covid, with a seven-day average of 59,578 cases. As such, XE probably represents only a small percentage of all Covid cases at present.

UKHSA data show that XE has a growth rate 9.8% above the value of BA.2, while the World Health Organization has so far stated this figure at 10%.

However, experts say they expect the severity to decrease, although it will spread more easily. XE has so far not been declared a cause for concern.

“XE seems to be moving in the same direction as BA.2, as it has increased transferability to BA.1, but is less serious,” Jennifer Horney, a professor of epidemiology at the University of Delaware, told CNBC.

“This is the devil we know, so to speak. [It is] basically moving the same set of cards, ”added Mark Cameron, an associate professor at the School of Medicine at Case Western Reserve University.

XE contains spikes and structural proteins from the same family of viruses, i.e. omicron, which means that it should at least theoretically behave the way omicron behaved before. Existing vaccines and immunity should therefore provide a certain level of protection against infection.

“Recombinants containing spikes and structural proteins from a single virus (such as XE or XF) are likely to act similarly to [their] parental virus, ”wrote Tom Peacock, a virologist in the Department of Infectious Diseases at Imperial College London. thread of tweets in the middle of March. XF refers to another recombinant discovered in the UK in February.

However, other recombinants containing spikes and structural proteins from different families of viruses continue to emerge. This includes the XD subvariant, recently discovered in Germany, the Netherlands and Denmark, which contains delta structural proteins and omicron spike proteins, and which Peacock described as “a little more worrying”.

Therefore, all new phenomena need to be closely monitored, especially in the early stages, to ensure that they do not develop into something more serious.

“The virus can still evolve, recombine, and develop a new branch of its family tree,” Cameron said.

“The key finding is that for each of these variants and subvariants, the risk of hospitalization and death appears to be lower on average if vaccination rates are higher, suggesting that vaccination, including the third dose, should be effective in reducing risks of serious illness, “added Stephanie Silvera, a professor of public health at Montclair State University.