With the booster programme at full tilt across the UK, immunity against Covid is rising, so it is perhaps not surprising that the concern shown by experts over the steep rise in Omicron has left some bewildered.
It is thought that the jabs still offer good protection against severe disease, even if the new variant dodges Covid vaccines. The ratio of hospitalisations to cases in the UK has been seen before, where 22% of cases in those aged 65 and older ended up in hospital in early 2021, when Alpha was dominant, but few had received a vaccine.
Even if the disease caused by Omicron is less severe than previous versions, most people will experience only mild symptoms thanks to their immune response or both.
This isn't about individuals. This is about the population.
Omicron infections are doubling more quickly than every two days in most regions of the UK, with the UK Health Security Agency's medical adviser saying infections could reach 1m a day by the end of the month.
It is not yet clear what the ratio of hospitalisations to cases will be with Omicron, but no vaccine offers 100% protection, meaning a proportion of those infections will end up in hospital, while many have yet to receive all of their jabs. Many experts have pointed out that even a small proportion of a large number is still a large number.
The point was made last week after data was released by the UKHSA showing two doses of a Covid vaccine offered far less protection against Omicron than Delta.
If we have a lot of people getting infections at the same time, it will find people who have less immunity, and people who have yet to get their booster dose.
Prof Chris Whitty has pointed out that a large wave of Covid hospitalisations would be a big problem for the health service, but that is not the only concern.
England's chief medical officer told MPs on Thursday that there would be a reduction in supply and an increase in demand over a short time period.
With the UK breaking records every day for the number of reported cases, the question is not whether hospitalisations will rise, but how long can the health service cope?
