The jab, seen as an alternative for people who are vaccine-hesitant, is widely available in the EU but still not cleared for use in the UK.
UK regulator the MHRA says Nuvaxovid is safe as a first and second dose in adults.
Sharman Finlay, 66, was one of 350 people in Northern Ireland who participated in Novavax trials.
The decision means thousands of people who took part in trials will be able to travel abroad.
Participants in the Novavax Covid-19 vaccine trial are not yet recognised as being fully vaccinated.
Derek Robson says Novavax has "washed their hands" of volunteers when it comes to boosters.
A volunteer in a vaccine trial says it has left her unable to travel and "invisible on the system".
Peter Harris from Consett cannot visit the country because he is now unable to get an approved jab.
CEO Martin Meeson says the vaccine will be ready by summer and he is "extremely proud" of his team.
