Omicron sub-variant almost as infectious as measles, the most contagious disease on earth

The new Omicron sub-variant is almost as infectious as measles, one of the most contagious diseases in human history, a top epidemiologist has warned.

The new variant - BA.2, also known as ‘stealth omicron’ - that combines mutations from both Omicron and Delta has been detected in a number of areas of France and it understood to have been circulating in the populace since January.

Professor Adrian Esterman, a former World Health Organisation (WHO) epidemiologist, told ABC news, that although the new sub-variant is not any more severe than Omicron, it is more transmissible. He said: “That means we’re going to see case numbers skyrocketing.”

On his Twitter account, he added: “Omicron BA.2 is about 1.4 times more infectious than BA.1. The basic reproduction number (R0) for BA.1 is about 8.2, making R0 for BA.2 about 12.

“This makes it pretty close to measles, the most contagious disease we know about.”

Only a small number of cases of the new variant have so far been identified and it is not yet clear how vaccines will protect against it.

Soumya Swaminathan, the chief scientist at the World Health Organization, tweeted on Tuesday: “We have known that recombinant events can occur, in humans or animals, with multiple circulating variants of #SARSCoV2.

“Need to wait for experiments to determine the properties of this virus. Importance of sequencing, analytics & rapid data sharing as we deal with this pandemic.”

And the Covid-19 technical lead for the WHO Maria van Kerkhove said on Twitter that her team were “tracking and discussing” the new variant.

Asked on Friday night if he had any concerns over the deltacron variant, UK health secretary Sajid Javid said: “There are variants that we would obviously keep under review.

“The most recent one of concern has been Omicron but we have successfully navigated our way through that as a country thanks to the response of the British people.

“There are also so-called subvariants of Omicron and we’re not concerned about any of those at this important time.

“We keep it under review but we have no concerns at all.”

This article was amended on 25 April 2022. It originally referred to BA.2 as ‘deltacron’, but that is a different strain.