The other big question that we need to understand concerns the severity of disease caused by Omicron. Some of the excitement around this question is puzzling. All variants of Covid-19 predominantly cause disease which is relatively mild and won’t put most people in hospital or intensive care. If we’re lucky, it might be that Omicron has a lower infection fatality rate than other variants. But Omicron will still kill and many people will end up on a ventilator after catching it. For those who are hit hardest there will be nothing mild about this disease.

If Omicron is killing fewer people per 1,000 infections elsewhere in the world, we shouldn’t assume this is because it’s intrinsically less virulent than other variants either. The severity of any infectious disease is a product of both the pathogen, the person it has infected and the surrounding environment…

The expectation that Omicron is a less severe version of Covid-19 has often been fed by the hackneyed assertion that viruses always become less virulent over time. While this is a plausible theory, the idea that it always happens and is some sort of concrete certainty is trite and utterly baseless – indeed pathogens can sometimes become better at causing severe disease. Certain journalists and politicians need to drop this misleading pseudoscientific nonsense. They should remember that most people over 50 will have had measles at some point in their lives, a 2000-year-old virus which can still cause serious illness and even be fatal.