A huge third wave of Omicron cases is sweeping the country. This will be readily apparent in the everyday lives of many people. Family members have it, work colleagues have gone down, small restaurants and service businesses must close for a few days through staff shortages.
According to the reliable Zoe Covid data produced by King’s College London, there have been two previous peaks, on 10 January and 13 February. The former was slightly higher in terms of the daily number of total cases, at 2.75 million compared to 2.68 million.
Already, the current surge has overtaken the previous peak. Yesterday, 3.4 million people in the UK were estimated to have Covid.
The peak of this wave has not yet been reached. This should be in the first few days of April, at over 4.25 million according to the Zoe data. It’s more than half the previous high point back in January.
In a seemingly paradoxical way, this is good news. Several bits of good news, in fact, the first of which takes a bit of time to explain.
Virologists established some time ago that the new variant of Omicron, the so-called BA.2 is even more infectious than the original version. Omicron itself is considerably more infectious than the previously dominant variants such as Delta.
In the opening months of the pandemic in spring 2020, there was a newfound obsession with a previously unknown and mysterious measurement – the “R” of the virus, or the initial “reproduction number”. Essentially, this is a measure of the ease with which any virus transmits itself in a social gathering.
We don’t hear much, if anything, about it these days. But the R number of the latest Omicron variant is so high that almost everyone in the country will end up catching it.
The epidemiological models themselves, as opposed to rules they have been used to justify, do have powerful insights.
One of these is a fairly simple formula which tells us the eventual proportion of a population which will end up having caught it – based on the R number.
But there is a major qualification to this, one which has tripped up the epidemiologists time and again.
The formula only holds good as long as behaviour remains unchanged.
If people respond to a virus by reducing their levels of social interaction, the effective level of the reproduction number is also reduced. And as a consequence, if the behavioural change persists, the eventual proportion of the population who catch it will be lower.
In the January and February waves of Covid, despite the relaxation of restrictions most people were exercising caution. Social mixing remained lower than what it was before the start of the pandemic in early 2020. But the massive surge during March shows very clearly that most people are now behaving very differently.
Further the ease with which the latest Omicron variant is transmitted means that it will shortly run out of people to infect. Re-infection does seem possible, but only at very low rates. So there are signs this latest wave really will be the last major one of Omicron.
In the meantime, rolling out the fourth wave of vaccines to the particularly vulnerable makes very good sense. Finally, it seems that Britain has learned to live with Covid-19.
