Investing is always the art of calculated risk based on imperfect knowledge, and epidemiology is no different. Based on what we know so far, the investible probability is that omicron is, if anything, the solution to the pandemic: a variant that spreads like wildfire but with mostly mild symptoms, delivering a short, sharp shock that clears the way for a rapid return to life as normal. This is bullish, ceteris paribus, but it also implies a hotter global economy in 2022 and therefore a quicker end to easy money.

China may have to miss the recovery party. The regime cannot keep such a transmissible variant out of the country without hermetically sealed isolation. The latest Hong Kong study found that the Sinovac jab offered no antibody defence at all against omicron.

In a sense China is stuck with the success of its zero-Covid policy, oversold at home as a propaganda triumph. It is forced to opt for scorched-earth suppression rather than put its vaccines to the test. China may be the great economic loser of the pandemic, trapped in semi-stagnation as the world moves on, the opposite of conventional wisdom a year ago.

The clinical evidence from Discovery Health in South Africa – three weeks into omicron – is that double vaccination leads to 70pc protection against hospitalisation, and only 5pc of those admitted need intensive care compared to 22pc for delta. The frontline antibodies may be falling off, but rearguard B and T cell memory is working like a charm.

Prof Francois Balloux, director of the UCL Genetics Institute, also has some gentle mockery for those purporting to control events. “There’s something touching about our attitude to Covid-19, like a child on a beach, cursing the incoming waves, and taking pride whenever one recedes towards the sea,” he said.

Unlike markets, politicians and health authorities cannot act only on probability. They must take into account extreme tail risks. Virologists do yet know exactly where omicron lies on the spectrum of virulence. A slight change in the number can lead to starkly skewed results either way. Modelling by Sussex University shows the UK death range of this wave varying from 9,460 to 171,000, depending on the degree of vaccine escape, booster efficacy and the counter measures taken to slow the spread.

Personally, I would have voted for the Prime Minister’s Plan B as an insurance policy. These are light-touch measures when set against the creeping coercion in parts of Europe, where mandatory jabs and abridged human rights for the unvaccinated are becoming almost de rigueur.

But I also share the suspicion of those 100 Tory rebels that the numbers are being cherry-picked to create alarm, and that we are talking ourselves into an unnecessary winter crisis that will push thousands of small businesses over the edge. Almost 96pc of the population already have Covid antibodies, and therefore T cell memory. More than 24m have had a booster jab, essentially covering the entire cohort of vulnerable people.

One is tempted to ask: if it were not for the mass testing, would the nation as a whole even be aware of this omicron wave? But that is to utter heresy in the age of Covid.