Moderna Inc has said it is working with US government scientists to study an experimental booster shot that targets a concerning new variant of the coronavirus, and has raised its global Covid-19 vaccine production goal for this year by 100 million doses.

The US biotech company has produced raw material for a booster shot aimed at addressing the virus variant first found in South Africa that may be more resistant to existing vaccines, it said.

It has shipped the vaccine to the US National Institutes of Health, which helped develop Moderna’s current vaccine, for additional study, Reuters reported.

Moderna is experimenting with several potential ways to combat new variants of the virus.