Scientific advisers are bracing themselves for hundreds of UK cases of the Omicron Covid variant to be confirmed in the next week or so, the Guardian has learned.
Some of them may predate the earliest cases of Omicron found in South Africa last week but could still be linked to travellers returning from the country, it is understood. Evidence of community transmission also emerged on Monday.
Omicron, which is believed to be more transmissible than dominant Covid-19 variants and has the potential to evade vaccines, was first reported to the World Health Organization from South Africa on 24 November.
The UK is one of the world’s busiest air transport hubs and, like South Africa, has a large genomics sector to determine the variants involved in infections – increasing the probability both of importing and detecting cases.
On Saturday, two UK cases were announced, rising to three on Sunday – all in people linked to travel to southern Africa. On Monday morning, six new cases involving the Omicron variant had been identified in Scotland and this time some had no travel history.
The finding has raised concerns Omicron may already be circulating in the community in the UK.
Scientists had previously stressed that while flight bans could delay the importation of Omicron, the variant would nonetheless arrive. It was hoped such measures would buy time and let more people get their booster jabs.
Now the Guardian understands that scientific advisers are bracing themselves for the possibility of several hundred cases of the Omicron variant being detected within days. Other scientists said the spread was difficult to estimate.
Prof Michael Tildesley, an expert in the mathematical modelling of infectious disease at the University of Warwick and a member of the modelling group Spi-M that advises the government, said: “It is worth remembering, though, that there is a lag between individuals being infected and cases being reported, so at the point that cases are detected, it is likely that there are more infections in the community.”
Tildesley added that at this point contact tracing could help to detect how many more cases there might be in the population. “But there is still uncertainty regarding how transmissible this new variant is, how effective the vaccines might be and how severe infection is with Omicron.”
Prof Rowland Kao, an epidemiologist at the University of Edinburgh who also contributes to Spi-M, said the discovery of two clusters of cases in Scotland – in Lanarkshire and Greater Glasgow – with no obvious links to each other or to travel, suggested at least two separate instances of importation. “For the moment, we do have to assume there is further community circulations,” he said, adding it would not be surprising to find tens of cases at the moment.
“Of course [if] it does spread rapidly, as initial reports from [South Africa] suggest it can, then it wouldn’t take long for it to go into the hundreds,” said Kao, adding that if the doubling time for cases was similar to the Delta variant, then 25 cases of Omicron now could mean 100 cases in 10 days’ time. “At that point, it would be more a matter of slowing, rather than eradicating Omicron in Scotland. Even then, it would probably only be temporary.”
But Kao said travel restrictions might still bring benefits, potentially reducing the number of outbreaks and, at least for now, helping stamp them out. “However that is not at all guaranteed, and so, as always, more efforts to reduce spread now, may have big epidemiological benefits later,” he said.
“Any measures we put in now may of course, prove unwarranted if in fact, the Omicron variant proves to be sufficiently benign that overall levels of severe infection and hospitalisation stay manageable – but we probably won’t know for several weeks.”
Some experts have called for robust action, including advice to work from home. Stephen Reicher, a member of the behavioural science advisory group Spi-B, and a professor of psychology at the University of St Andrews, said: “With Omicron, even if it turns out to be less serious than we feared, we need to put basic protections in place.”