A World Health Organisation panel recommends the Oxford-AstraZeneca vaccine for anyone over 18 years of age
In some European countries, including France, Germany and Denmark, the vaccine was approved for use only in the under-65 age group, with those nations citing a lack of data on safety.
"Taking the totality of available evidence into account, WHO recommends the vaccine for use in persons aged 65 years and older," the 15-member Strategic Advisory Group of Experts on Immunisation said in their new recommendations.
"In the case of the data coming from clinical trials, we have seen that there was a small participation of people over 65 years of age," said Dr Alejandro Cravioto, the chairman of the group.
"However, the results of the efficacy estimate for persons up to 65 and older had a wide confidence interval. And therefore we feel that the response of this group cannot be any different to groups that are of a younger age," he said.
The body also recommended the use of the vaccine in places where "variants are present", despite a recent study suggesting it was far less effective against a new strain of the virus first detected in South Africa.
The WHO report said that the longer the interval between the two doses of the AstraZeneca vaccine (within a four to 12-week range), the greater its efficacy.
The findings raised hopes the vaccine would be added to the WHO's emergency approval list.
"We hope this will be followed very soon by the emergency-use listing of this product," WHO chief scientist Soumya Swaminathan said.
This is a positive development for poor countries relying on the Covax programme, which aims to distribute vaccines equitably around the world.
The occupied Palestinian territories, Yemen and Sudan are among the nations that have applied for vaccines through the Covax programme, as richer countries began inoculating their populations by the millions.
AstraZeneca pledged significant supplies to Covax.
Unlike the Pfizer-BioNtech vaccine, which needs special cooling refrigerators not readily available in poor countries, AstraZeneca’s shot is easier to transport and store, and it also costs less.
As mutated virus strains spread around the globe, concern grows that they will affect vaccine efficacy.
South Africa, where one of the variants was first identified late last year, said it would pause distribution of AstraZeneca’s vaccine after a trial showed it had limited efficacy against mild cases of the new strain.
Pascal Soriot, AstraZeneca's chief executive, said the drug should still protect against severe disease, and WHO officials underlined the benefits of continuing to use the vaccine even in variant-hit areas.
Evidence is still being gathered on the vaccine's efficacy for pregnant women, the WHO report said.
