Health care providers hope the Novavax COVID-19 vaccine will appeal to people who haven't recieved any doses of previous vaccine iterations. 

Adults who haven't gotten any COVID-19 shots should consider the new option, the agency said Tuesday. The spike protein vaccine is more typical than the mRNA types being broadly used against COVID.

Advisers to the Food and Drug Administration overwhelmingly voted to recommend that it authorize Novavax's two-dose vaccine against COVID-19.

The Novavax vaccine appears to be about 90% effective at preventing mild, moderate and severe COVID-19, Food and Drug Administration scientists say in an analysis of the company's data.

Protein subunit vaccines work by injecting people with a tiny portion of a virus. In the case of the COVID-19 vaccine, that tiny portion is the spike protein that the coronavirus uses to enter cells.

Instead of putting genetic instructions into people whose cells then make a viral protein, the vaccines from Novavax, Medicago and Sanofi carry a spike protein payload.

The $1.6 billion Novavax contract is one of several Operation Warp Speed agreements issued through a third party, Advanced Technology International, and that hadn't been released.