A top U.S. scientist said on Wednesday that governments should not count on a successful vaccine against COVID-19 being developed anytime soon when deciding whether to ease restrictions imposed to curb the pandemic.

William Haseltine, a groundbreaking researcher of cancer, HIV/AIDS and human genome projects, said the better approach now is to manage the disease through careful tracing of infections and strict isolation measures whenever it starts spreading.

While a COVID-19 vaccine could be developed, he said, "I wouldn't count on it."