Researchers in Hong Kong have urged people to get a third dose of a Covid-19 vaccine as soon as possible after a study showed insufficient antibodies were generated by the Sinovac and BioNTech products to fend off Omicron.

The release of the results of a study by scientists in the microbiology department of the University of Hong Kong was the first published preliminary data on the impact of Sinovac's vaccine against the Omicron variant of coronavirus, Reuters reported.

None of the serum of the 25 Coronavac vaccine recipients contained sufficient antibodies to neutralise the new variant, according to the study, accepted for publication in the journal Clinical Infectious Diseases, the researchers said.

“The public is advised to get a third dose of the vaccine as soon as possible while waiting for the next generation of a more matched vaccine,” the researchers said in a news release.