US biotechnology firm Moderna said lab studies showed its Covid-19 vaccine would remain protective against variants of the coronavirus first identified in the United Kingdom and South Africa, AFP reports.

But out of caution, the company will test adding a second booster of its vaccine — to make three shots in total — and has begun preclinical studies on a booster specifically for the South African variant.

“We are encouraged by these new data, which reinforce our confidence that the Moderna Covid-19 vaccine should be protective against these newly detected variants,” said Stephane Bancel, Moderna's CEO.