The World Health Organisation recommends using the AstraZeneca vaccine against COVID-19, despite recent reports questioning its effectiveness.

The UN health agency issued its guidance on Wednesday, days after the publication of a study showing that the vaccine offers less protection against the 501Y.V2 variant of the novel coronavirus that was first detected in South Africa.

The WHO noted that the results of the study showed only limited effectiveness against mild forms of COVID-19 but that there was no evidence that the vaccine does not protect against severe disease.

Following the advice of an international panel of 26 vaccine experts, the WHO recommended the use of AstraZeneca “even if variants are present in a country”.

The WHO’s top immunisation specialist, Kate O’Brien, said all vaccines tended to be less effective against mild forms of disease.

“There is a plausible expectation that the vaccine will have efficacy against severe disease,” she said about the product, which was developed by the British-Swedish pharmaceutical giant AstraZeneca and the University of Oxford.

Kate O’Brien is the Director of the WHO’s Department of Immunization, Vaccines and Biologicals. Photo: GAVI

Dr O’Brien said people who had received any of the available COVID-19 vaccines must keep following pandemic precautions, including physical distance and masks.

While the shots prevent people from falling ill with COVID-19, there was a risk they could still transmit the virus to others, she said.

The WHO said in its recommendation that there was an “urgent need” for global monitoring of new virus variants, which would allow scientists to draw conclusions on vaccines.

Although there are indications that variants detected in Britain, South Africa and Brazil are more infectious than earlier ones, global COVID-19 case numbers have been falling for the past four weeks, according to the latest WHO update.

Numbers fell in all world regions last week.

The downward trend includes Britain and South Africa, thanks to strict public health measures in both countries, according to the WHO.

-AAP