Novavax Inc and its partner Serum Institute of India have applied to the World Health Organization for an emergency use listing of Novavax's COVID-19 vaccine, the company said on Thursday.

The WHO's emergency use listing is a signal to national regulatory authorities on a product's safety and efficacy.

It is also a prerequisite for export to several countries participating in the COVAX vaccine sharing facility.

Novavax has said it would focus on low- and middle-income countries for initial supplies of the vaccine, as the United States and other Western nations have already vaccinated a large part of their populations with other vaccines.

Novavax had previously said it would apply for the listing in August, marking a slight delay in the filing.

Novavax and Serum Institute, the world's largest vaccine producer, have committed to together provide more than 1.1 billion doses to the COVAX facility, which aims to provide equitable access to COVID-19 vaccines to low- and middle-income countries.

The Novavax shot is a protein-based vaccine, and was shown to be more than 90% effective, including against a variety of concerning variants of the coronavirus in a large, late-stage U.S.-based clinical trial.