GENEVA: AstraZeneca's Chief Executive said on Tuesday that the results of a study showing its COVID-19 vaccine had little effect against mild disease were concerning but stressed that it should work against severe forms.

"It is of course a concern," Pascal Soriot said of the study at a World Health Organization meeting. "Having said that the patients in the study were patients with mild disease and we believe the vaccine should still protect against severe disease."

AstraZeneca is a major supplier to a WHO-backed vaccine-sharing scheme called COVAX.