New York, Jul 14 (IANS): The US Food and Drug Administration (FDA) has authorised Novavax's Covid-19 vaccine for emergency use in adults.

According to CNN, it is the fourth coronavirus vaccine available in the US, and it uses a different type of vaccine technology than the shots already available.

Novavax's vaccine will be available as two-dose primary series for people aged 18 and above. The FDA's independent Vaccines and Related Biological Products Advisory Committee voted in favour of authorisation of the vaccine on June 7, saying that the benefits of the vaccine outweigh its risks for adults.

It is also being used in 170 other countries. The shots cannot be administered until the US Centres for Disease Control and Prevention's independent vaccine advisers weigh in on whether to recommend the vaccine and the CDC director has signed off on the recommendation. The CDC's Advisory Committee on Immunisation Practices is scheduled to meet on July 19.

Like more familiar vaccines such as hepatitis B and pertussis, the Covid-19 vaccine is protein-based, using harmless protein fragments of the virus to teach the immune system how to spot the virus and fight it off.

The vaccine was created out of a genetic sequence of the first strain of the coronavirus, the report said.

Unlike some other Covid shots, Novavax's vaccine can be stored in standard refrigeration.

Late-stage trials found that the efficacy of the vaccine against the mild, moderate and severe diseases is 90.4 per cent, according to the company. There is not sufficient evidence to evaluate the impact of the vaccine on the transmission of the virus.