Moderna Inc has said that a booster dose of its Covid-19 vaccine appeared to be protective against the fast-spreading Omicron variant in laboratory testing and that the current version of the vaccine would continue to be Moderna's “first line of defence against Omicron”.

The vaccine maker said the decision to focus on the current vaccine, mRNA-1273, was driven in part by how quickly the recently discovered variant is spreading. The company said it still plans to develop a vaccine to protect against Omicron and hopes to advance into clinical trials early next year, Reuters reports.

“What we have available right now is 1273,” Dr Paul Burton, Moderna's Chief Medical Officer, said in an interview.

“It's highly effective, and it's extremely safe. I think it will protect people through the coming holiday period and through these winter months, when we're going to see the most severe pressure of Omicron.”