The World Health Organization on Friday issued an emergency use listing to Serum Institute of India's version of Novavax Inc's COVID-19 vaccine, paving the way for the two companies to ship their doses for the COVAX program.

The EUL to the shot, Covovax, marks a significant milestone for Novavax as well, after the vaccine had been caught up with delays, especially in ramping up production. Shares of Novavax were up 6.4% on the news. 

Novavax's own vaccine Nuvaxovid, though, is currently under assessment by the European Medicines Agency, and the WHO said it will complete its own assessment of the shot once the EMA has issued its recommendation.

For WHO, the clearance for Covovax will provide a significant boost to improve access to COVID-19 vaccines in poor countries under the COVAX program, which has been marred by delays this year. 

"This listing aims to increase access particularly in lower-income countries, 41 of which have still not been able to vaccinate 10% of their populations, while 98 countries have not reached 40%," Dr Mariângela Simão, WHO assistant-director general for Access to Medicines and Health Products said in the statement. 

Novavax and Serum Institute, the world's largest vaccine producer, have together committed to providing more than 1.1 billion doses to the COVAX facility.

The protein-based vaccine by Novavax in June was shown to be more than 90% effective, including against a variety of concerning coronavirus variants, in a late-stage U.S. trial.

"This vaccine can be used in a variety of contexts and will provide countries with another critical option in the quest to protect their populations," said Seth Berkley, chief executive officer of GAVI, the Vaccine Alliance.