December 16, 2021 - 2:00pm

Britain has pinned its hopes on the booster drive protecting us from Omicron. Only minor non-pharmaceutical measures, including a request to work from home if possible and reinstatement of mandatory masks in some public spaces, are being put in place. Instead, the plan is to give the booster to every adult by the end of December.

Or is it? First, as has been widely reported, the NHS seems to disagree: health service leaders say the goal is only to offer the jab to everyone by December, and actually giving them will take until February.

But let’s assume Boris Johnson is right about his own policy, and that the goal is to get actual jabs in actual arms by the new year. The trouble is: by the Government’s own rules, that’s not possible.

You are allowed to get your booster if you had your second jab at least three months ago. You can book it two months after you get your second jab, but you can’t actually receive it for another month. 

So on 31 December, everyone who had their jab on or before 30 September would be allowed to get a booster. According to the Covid dashboard, 37 million adults had had their second jab in England by 30 September.

But according to the ONS, there are 44.5 million adults (over 18) in England. Based on data from the National Immunisation Service, NIMS, that figure is 50 million. Kevin McConway, an emeritus professor of statistics at the Open University who alerted me to this issue, says the true figure is likely somewhere in between.

So there are at least 7.5 million adults, and probably more, who can’t have their jab by the end of 31 December, even if it is logistically possible to do so, because the Government’s own rules say it is impossible. That’s between 15% and 25% of the adult population.

That figure is in fact too low, because you also can’t be boosted if you’ve had a positive PCR test in the last 28 days. At the moment there are probably well over a million people in that situation — there have been at least 40,000 positive tests a day every day for the last several months, which is about 1.1 million every 28 days. On Wednesday, the figure was almost 80,000, and I expect it to go up. It could easily be that four million or more people are ineligible for boosters by the end of December because they’ve had the virus recently.

To be fair to Johnson, he did say “eligible adults” in his address. But the adverts all say “every adult is now eligible”. That’s flatly not true. Even in the implausible situation that the booster race goes perfectly, we will still have up to a quarter of the adult population unboosted because the rules say they can’t be. And perhaps that’s the right thing to do! But it’s worth being aware of.

In a secondary point, amazingly, reinfections are currently not counted in the case data. The “About the data” page says: “If a person has more than one positive test, they are only counted as one case for all nations with the exception of Wales.”Robert Peston pointed this out in July, and said it meant we might be severely undercounting. That was not true at the time — fewer than 1% of cases were reinfections and it probably didn’t make much difference. But now, I expect, a decent fraction of new cases will be reinfections, given that the Omicron variant is spreading so quickly, and given that it seems perfectly capable of evading immunity in many cases. Since that fraction is only going to rise, this seems an obvious thing to change. Apparently the UK HSA is working on it; hopefully it won’t take too long.

Tom Chivers is a science writer. His second book, How to Read Numbers, is out now.