It is also worth noting that this data only runs up to December 9, four days before new working from home guidance came into effect – so we can assume that contact rates are even lower now. There may be little wiggle room for limiting contacts, even with strict interventions. 

Greater risk of omicron infections

The other reason that restrictions may not be as effective this time is that omicron seems to be resisting all efforts to keep it at bay. 

Latest data from the UK Health and Security Agency suggest that those infected have three times the risk of passing omicron to a household member compared to delta. Imperial modelling has found that risk of reinfection with omicron is 5.4 times greater than that of the delta variant.

The most recent hospital acquired infection data also shows that rates have risen steeply in December, with at least eight per cent of Covid cases having not developed symptoms until at least two days after admission. The majority did not develop symptoms until a week of being in hospital. 

In latest advisory documents from the Scientific Advisory Group for Emergencies (Sage) experts also warned that hospital-acquired transmission “is an even greater risk as a result of omicron”.

Professor Paul Hunter, of the University of East Anglia, said: “The fact that about three quarters of those are developing symptoms after seven days does suggest that at least that proportion are hospital acquired. 

“So hospital-acquired infections appear to be more of a risk with omicron than previously.”

Sage also admitted that recent changes in behaviour, such as increased use of face coverings and reductions in contact, could be “potentially significant” – which had not been fully factored into models because of the uncertainty.

Rapid rise in omicron cases could be followed by rapid fall

And there may be some benefits to letting this wave run its course. An extremely fast, ultra-transmissible wave is likely to peak earlier, rather than being dragged out.

If the country follows the trajectory of South Africa, where omicron was first identified, we might expect cases to fall just as dramatically as they rose. In Covid hotspots such as Guatang, the epidemic was starting to decline within three weeks of it starting.