LONDON: New guidance from the World Health Organization (WHO) has affirmed the British view that the Oxford-AstraZeneca vaccine is safe for all adults, and that its second dose should be delayed.

The British strategy, of offering the jab to over 65s and delaying the second dose, was met with skepticism from some EU members, some of whom have banned over 65s from receiving the AstraZeneca vaccine, citing a lack of data proving its efficacy.

But new guidance from a WHO advisory group released on Thursday cited data showing good immune responses from older people from the jab.

“This suggests it is likely that the vaccine will be found to be efficacious in older persons,” the group said. “The trial data indicate that the vaccine is safe for this age group. Taking the totality of available evidence into account, the WHO recommends the vaccine for use in persons aged 65 years and older.”

The group also found that “vaccine efficacy tended to be higher when the interval between doses was longer,” and concluded that other countries should follow Britain’s dosing plans with the jab.

The WHO still says doses of the Pfizer-BioNTech vaccine should be given no more than six weeks apart, but added that these guidelines are open to the possibility of revision.

British Prime Minister Boris Johnson said it was “good to see” the WHO’s judgment, which will be taken as a vindication of the controversial decision to disregard manufacturer advice and delay doses between jabs in order to spread virus protection more widely.

The UK is among the world’s fastest vaccinating countries, having already inoculated over 13 million people, with a strategy of prioritizing the elderly and healthcare workers. 

Prof. Katherine O’Brien, director of the WHO’s immunization department, said: “There is no reason to expect that efficacy is substantially compromised in older people.”

Given that “the over-65s are at the very highest risk of severe disease and death (and we have) a product that has significant efficacy … there is no reason to constrain the AstraZeneca product from a general recommendation,” she added.