Why Hong Kong is extending restrictions, even as cases drop to zero

At a press conference Tuesday, Dr. Gabriel Leung, the Dean of Medicine at the University of Hong Kong, said there was a “three-way tug of war” between protecting public health, livelihoods and mental health, but believes it is too soon to loosen the restrictions.

Experts say it will be a while before life can go back to normal. “We need a bit more time to try to stop the chain of transmission in the community,” David Hui, a respiratory medicine expert at the Chinese University of Hong Kong, tells TIME.

Hui believes that restrictions should be in place until 28 days—or two virus incubation periods—have passed with no new locally transmitted cases. And even then, he says any sort of reopening should follow a phased approach. Officials reported four cases on Tuesday, though all of them were people who had traveled recently from the U.S. and U.K.