A new COVID-19 subvariant that has been named XBB.1.5., is spreading rapidly in the US and doubling the number of positive cases in just one week.

According to health experts, it unfortunately risks becoming dominant on a global scale as well.

Experts say this is the most infectious subvariant of Omicron detected in 29 countries so far.

The variant appears to have originated in New York City, where it was first detected in late October. In addition, more than 40 % of COVID-19 cases in the U.S. are now caused by the XBB.1.5 strain, data from the U.S. Centers for Disease Control and Prevention showed last Friday.

So far, according to doctors, there is no evidence that the severity of the disease has changed. However, the World Health Organization (WHO) believes it is important to monitor its spread because only in the last month, there has been a 15 % increase in deaths from COVID-19 worldwide.

British scientists believe it is likely – though not certain – that XBB.1.5. will cause a new wave of COVID-19 by the end of January.

Wendy Barclay from the Imperial College of London told BBC that there is no evidence that XBB.1.5. could massively disrupt the protection provided until now by the anti-COVID vaccines.