Once its most advanced candidate, Soberana (Sovereign) 2, has completed Phase II trials which started on Dec. 22, it will be tested in Phase III trials in around 150,000 people in Havana, officials have said.

Yet the Caribbean country will need to conduct more late stage trials abroad too given it does not have a high infection rate due to its successful management of its outbreak, they said. Iran, meanwhile, has been the worst-hit country in the Middle East.