Moderna Inc. said on Wednesday it is working with U.S. 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 U.S. 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 United States' National Institutes of Health for additional study.

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

They include an additional booster shot that targets the variant now prevalent in South Africa and spreading globally, a combined booster shot that mixes its current COVID-19 vaccine with the experimental shot, and an extra booster shot on top of its current two-dose vaccine, the company said.

The United States discovered its first case of the South African variant in January and it has since turned up in several states. Several studies suggest it is more resistant to existing vaccines than other variants of the coronavirus.

Moderna also raised its expected vaccine production for 2021 to 700 million doses globally from 600 million and is exploring further improvements to its manufacturing process that could raise production this year to as much as 1 billion doses.

The company said it is also investing in additional manufacturing capacity that should bring its 2022 global production to around 1.4 billion doses.