The supply from Pfizer and Moderna is now the main limiting factor in the coronavirus vaccine programme, analysts say, preventing a reduction in the eight-week interval between doses as the race against the Delta variant continues.
The government was advised last month under-40s should be offered an alternative to the Oxford-AstraZeneca jab because of a small risk of blood clots, given the low prevalence of the virus and the availability of other shots.
Only imported doses of the Pfizer-BioNTech and Modena vaccines are being used for people in their twenties and thirties. It appears from the data available that Pfizer and Moderna supplies are the pace-limiting factor, Matt Linley, an analyst at Airfinity, a data company tracking the vaccine campaign, said.
Getting as many