“But people should not be too anxious. Remember there are a number of vaccine candidates coming online at the same time,” WHO spokeswoman Margaret Harris told a U.N. briefing in Geneva.

“One vaccine may not be suitable for particular individuals, but you may well find another vaccine is.”

The setback affects one of the most established technologies in vaccines – used against the human papillomavirus, hepatitis B and pertussis among other pathogens – which aims to introduce lab-made proteins into the body to prod the immune system into developing a targeted defence against the novel coronavirus.

“As ADB’s developing members prepare to vaccinate their people as soon as possible, they need financing to procure vaccines as well as appropriate plans and knowledge to be able to safely, equitably, and efficiently manage the vaccination process,” ADB President Masatsugu Asakawa said.

Healthcare workers and elderly people in long-term care facilities are expected to be the main recipients of a first round of 2.9 million doses.

Cases are surging in the United States, with thousands of death per day, while hospital intensive care units across the country are nearing capacity, threatening to overwhelm healthcare systems.

The FDA found the vaccine highly effective across various demographic groups. But it’s unclear how well the vaccine works in people with HIV and other immune-system disorders.

It wasn’t immediately clear if the announced results included only those taking part in the testing in the UAE or if they also include results from China and elsewhere.

The statement described the vaccine as receiving official registration without elaborating on what that meant. Emirati officials could not be immediately reached for comment.