Sinovac Biotech's Covid-19 vaccine may not trigger sufficient antibody responses against a new variant identified in Brazil, a small-sample lab study showed.

The emergence of variants of the new coronavirus has raised concern that vaccines and treatments that were developed based on previous strains may not work as robustly.

Plasma samples taken from eight people vaccinated with Sinovac's CoronaVac failed to efficiently neutralise the P.1 lineage variant, or 20J/501Y.V3, researchers...