Experts say almost everyone is set to be infected by the new strain thanks to how easily it seems to spread – BA.2 appears to cause less severe disease than previous strains but can can still be dangerous
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A new variant of Covid-19 could be of the most infectious diseases the world has ever seen, an epidemiologist has said.
Professor Adrian Esterman, an epidemiologist and biostatistican, says the variant is up to six times more transmissible than the original strain of Covid – and we can expect most people to catch it.
While it is less deadly, BA.2 is a mutation of the Omicron variant of coronavirus and now accounts for the majority of new infections in the UK.
BA.2’s R number, the rate at which it can spread, is 12, compared to 2.5 for the original virus.
Prof Esterman told MailOnline this level of infectiousness makes the new strain “pretty close to measles, the most contagious disease we know about”.
BA.2 appears to cause less severe disease than previous strains but, like all strains, can be dangerous, he added.
He said: “The trouble is it causes more severe disease in vulnerable people than influenza, and it has the capacity to cause real damage to younger people too.
“There have been several cases of young, healthy and fit people dying from Covid.
“I cannot remember that ever happening with influenza.
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“Covid-19 can attack every part of the body, from clotting to the heart and brain.
“There have even been cases of young children with multi-system inflammatory condition.
“It is true that pandemics become less infectious over time, but that happens over 100 years, not one year.”
Rising Covid-19 infections are being driven by a jump in outbreaks among 30 to 49-year-olds, while rates are highest in south-west and south-east England, new figures suggest.
Public health experts have warned the virus is circulating at “increasing levels”, with several factors likely to be responsible, including the increased transmissibility of the BA.2 variant and the scrapping of rules for self-isolation.
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All age groups and regions saw a rise in Covid-19 activity last week, according to the UK Health Security Agency (HSA).
It comes as the WHO said Covid-19 is yet to settle into a “seasonal or predictable” and dismissed the notion that the virus was “through it in the northern hemisphere until next winter” as it highlighted rising cases of the virus in the UK .
Dr Mike Ryan, executive director of the WHO’s health emergencies program, added: “The virus is still moving around quite easily and in the context of waning immunity and the fact that vaccines don’t work perfectly against infection, the likelihood is that this virus will echo around the world.
“The virus will pick up pockets of susceptibility and will survive in those pockets for months and months until another pocket of susceptibility opens up.
“It has not settled down into a purely seasonal or predictable pattern yet.
“So the idea that we’re through it in the northern hemisphere now and we’ve got to wait till next winter – I think when we look at increasing rates for example of cases in the likes of the UK, I think we need to be very, very, very vigilant.
“We need to be very cautious. We need to watch this very carefully.”