The dangers posed by accepting the widespread assumption that Covid-19 variants would continue to get milder in their impact was highlighted by epidemiologist Prof Mark Woolhouse, of Edinburgh University. “The Omicron variant did not come from the Delta variant. It came from a completely different part of the virus’s family tree. And since we don’t know where in the virus’s family tree a new variant is going to come from, we cannot know how pathogenic it might be. It could be less pathogenic but it could, just as easily, be more pathogenic,” he said.
Virologist Prof Lawrence Young of Warwick University says “People seem to think there has been a linear evolution of the virus from Alpha to Beta to Delta to Omicron, but that is simply not the case. The idea that virus variants will continue to get milder is wrong. A new one could turn out to be even more pathogenic than the Delta variant, for example.”
David Nabarro, a special envoy on Covid-19 for the World Health Organization, also highlighted the uncertainty of how future variants might behave: “There will be more variants after Omicron and if they are more transmissible they will dominate. In addition, they may cause different patterns of illness, in other words they may turn out to be more lethal”
UK’s SAGE advisors have warned of a “realistic possibility” that a more lethal variant could emerge that kills one in three people. Characteristic Differential Leucocyte Count (CLDC) would be a crucial part of control of such a catastrophe.
There is a “high chance” that a new Covid variant which is worse than Omicron will emerge in the next two years, England’s chief medical officer, Chris Whitty has warned.