Senior doctors are calling on England’s chief medical officer to cut the gap between the first and second doses of the Pfizer-BioNTech Covid-19 vaccine.
Prof Chris Whitty said extending the maximum wait from three to 12 weeks was a “public health decision” to get the first jab to more people across the UK.
But the British Medical Association said that was “difficult to justify” and should be changed to six weeks.
It comes as early evidence suggests the UK virus variant may be more deadly.
Prime Minister Boris Johnson told a Downing Street briefing on Friday: “In addition to spreading more quickly, it also now appears that there is some evidence that the new variant – the variant that was first identified in London and the south east – may be associated with a higher degree of mortality.”
Previous work suggests the new variant spreads between 30% and 70% faster than others, and there are hints it is about 30% more deadly.
For example, the government’s chief scientific adviser Sir Patrick Vallance said if 1,000 men aged 60 were infected with the old variant, roughly 10 of them would be expected to die – but this rises to about 13 with the new variant.
A further 40,261 cases, and 1,401 deaths within 28 days of a positive coronavirus test were reported on Friday in the UK.
The government’s Joint Committee on Vaccination and Immunisation (JCVI) says unpublished data suggests the Oxford-AstraZeneca vaccine is still effective with doses 12 weeks apart – but Pfizer has said it has tested the vaccine’s efficacy only when the two doses were given up to 21 days apart.
Speaking alongside Mr Johnson at the briefing, Prof Whitty said increasing the gap between doses to a maximum of 12 weeks would allow “many more people to be vaccinated much more quickly”.
The World Health Organization has recommended a gap of four weeks between doses – to be extended only in exceptional circumstances to six weeks.
The Department of Health and Social Care said the decision to extend the maximum gap between doses for both the Oxford and Pfizer vaccines “followed a thorough review of the data and was in line with the recommendations of the UK’s four chief medical officers”.
“Our number one priority is to give protection against coronavirus to as many vulnerable people as possible, as quickly as possible,” a spokeswoman added.