The European Medicines Agency said on Monday that the maximum interval of 42 days between the first and the second dose of the Pfizer-BioNtech vaccine should be respected to obtain full protection.
Evidence of the vaccine efficacy is based on a study where administration of doses was done 19 to 42 days apart, the agency said, noting that full protection comes only seven days after the booster.
It added: "Any change to this would require a variation to the marketing authorisation as well as more clinical data to support such a change, otherwise it would be considered as 'off label use'."
Off label use entails lower liabilities on vaccine makers.
(Reporting by Francesco Guarascio; Editing by Andrew Heavens)
