It is not a good study: "A total of 503 healthcare workers were recruited to the study, of which 223 (44%) had previously had Covid-19." The sample group is not representative of the population and with a large proportion already having had COVID, it is expected that the first dose of the vaccine acts like the second dose, and a second dose as a booster.

It is also ignoring the downsides of the longer gap, the main one being the increased likelihood of creating a vaccine resistant escape variant. The UK government admits that this is a risk: https://assets.publishing.service.gov.uk/government/uploads/...

"There is therefore an increased risk of virus replication under partial immunity after one dose than after two doses, so in the short- term, delaying the second dose would be expected to somewhat increase the probability of emergence of vaccine resistance - but probably from a low base."

Last time I looked, UK now had the 3rd highest case rate in the world. A variant factory you could call it.

Part of the justification of the risks of the increased gap was the high death rate at the time.

"Is such an increase material? It is not currently possible to quantify the probability of emergence of vaccine resistance as a result of the delayed second dose, but it is likely to be small. The UK currently has more than 1,000 COVID-19 related deaths each day and has limited supplies of vaccine. In the current UK circumstances the unquantifiable but likely small probability of the delayed second dose generating a vaccine escape mutant must be weighed against the measurable benefits of doubling the speed with which the most vulnerable can be given vaccine-induced protection."

That is no longer the case, vaccine supply is good and take-up is falling.

The Oxford AstraZeneca vaccine did have clinical trials with a longer gap as far as I understand, but Pfizer didn't. The mRNA vaccines have different properties but the UK government is treating all vaccines as the same.

Now with every small and pretty weak bit of evidence the government jumps on to justify their decision, which initially may have been the right choice but the unlocking and delta variant have changed the situation massively.

There was a similar study in Israel with some strong arguments against its findings: https://www.thelancet.com/journals/lancet/article/PIIS0140-6...

And more good reading: http://www.thelancet.com/retrieve/pii/S0140673621004554

"We have no concerns regarding the second dose of AZD1222 at 12 weeks, as this is supported by evidence. However, if escape variants arise due to sub-optimal dosing with BNT162b2, they will likely be resistant to other vaccines that target the same viral spike protein. In conclusion, we would strongly recommend that the UK Government reverts to the two doses in a 3-week schedule (94% efficacy) for BNT162b2; or, as recently supported by WHO and the US Centers for Disease Control and Prevention, adopt no more than a 6-week delay to the second dose “in exceptional circumstances”."