There is some very odd stuff going on in the UK regarding vaccination schedules - specifically the gap between the first and second injection of the Pfizer vaccine.
The Pfizer vaccine was authorised for emergency use with the two doses being given 21 days*apart
The A-Z vaccine was authorised for emergency use with the two doses being given 4-12 weeks apart
When the A-Z vaccine was authorised, the timing was changed for the Pfizer vaccine doses thus:
The Joint Committee on Vaccination and Immunisation (JCVI) has subsequently recommended that as many people on the JCVI priority list as possible should sequentially be offered a first vaccine dose as the initial priority. They have advised that the second dose of the Pfizer/BioNTech vaccine may be given between 3 to 12 weeks following the first dose…
OK, so this expedites rollout (a good thing, obviously), but is it supported by the data?
The following is from Information for Healthcare Professionals on Pfizer/BioNTech COVID-19 vaccine
In Study 2, approximately 44,000 participants 12 years of age and older were randomised equally and received 2 doses of COVID-19 mRNA Vaccine or placebo with a planned interval of 21 days. The efficacy analyses included participants that received their second vaccination within 19 to 42 days after their first vaccination.
Source. My bold.
So it wouldn’t be unreasonable to ask, where’s the data to support 12 weeks then? Just like this:
Plaid Cymru has called on the Welsh Government to ask the UK government to publish evidence to justify increasing the period between the two doses of the Pfizer-BioNTech vaccine from 21 days to 12 weeks…
…He added there were “very real concerns” that a longer delay between doses “could significantly decrease the effectiveness of the vaccine”.
At this point, I’m left wondering what Pfizer would have to say about it. Fortunately, Reuters has reported it:
Pfizer sounded cautious on the prospect of shifting the schedule of its second dose, noting it had not been evaluated on different dosing schedules.
“There are no data to demonstrate that protection after the first dose is sustained after 21 days,” it said in a statement, adding that the implementation of alternative schedules should be closely monitored.
(*) - it may have been at least 21 days - I can’t access the documents as originally published
PS: Bloomberg also report Pfizer’s concerns. Their report also includes this:
Anthony Fauci, the top U.S. infectious disease expert, also weighed in on the U.K.’s decision in an interview on NBC’s Today Show on Thursday. Spreading out the two doses is “under consideration,” he said, though he didn’t specify by who.
“I still think, if done properly, you can do a single dose, reserve doses for the second dose, and still get the job done,” Fauci said. But he added “you can make an argument, and some people are, about stretching out the doses and giving a single dose across the board and hoping you’re going to get the second dose in time to give to individuals.”