WHO backs up AstraZeneca vaccine use amid efficacy concerns

World Health Organization (WHO) has decided that potential benefits of the Oxford-AstraZeneca Covid-19 vaccine outweigh known and potential risks, amid concerns over its efficacy against the virus variant found in South Africa.

The WHO also says the vaccine can be used in people aged over 65, which some countries have advised against. It has also advised that spacing out the two doses makes the vaccine more effective.

The WHO Strategic Advisory Group of Experts on Immunization (SAGE) panel on Wednesday said the two-dose AstraZeneca vaccine efficacy tended to be higher when the interval between doses was within the four to 12 weeks range, reports Xinhua news agency.

It also added that although preliminary analyses based on a small sample size in South Africa indicate a marked reduction in vaccine effectiveness against mild and moderate disease, it did not allow a specific assessment of vaccine efficacy against severe Covid-19.

As indirect evidence is compatible with protection against severe Covid-19, the situation remains to be demonstrated in ongoing clinical trials and post-implementation evaluations.

In view of this, WHO currently recommends the use of the AstraZeneca vaccine even if the variants are present in a country.

Countries should conduct a benefit-risk assessment according to the local epidemiological situation, including the extent of circulating virus variants.

"We have made a recommendation that even if there is a reduction in the possibility of this vaccine having a full impact in its protection capacity, especially against severe disease, there is no reason not to recommend its use even in countries that have circulation of the variant," said SAGE chair Alejandro Cravioto at a briefing on Wednesday.

Meanwhile, SAGE cautioned that as there are currently no efficacy or safety data for children or adolescents below the age of 18 years, vaccination of individuals below 18 years of age is not recommended until such data are available.

South Africa said recently that the rollout of the AstraZeneca vaccine in the country would be temporarily put on hold until more "clinically efficacy information" of the vaccine against new Covid-19 variant becomes available.

The decision came after a study showed that the AstraZeneca vaccine was less effective against the new variant found in South Africa.