Authorities will suspend flights and trains out of the Chinese city , saying residents should not leave without a special reason.
The move is meant to "resolutely contain the momentum of the epidemic spreading" and protect lives, Wuhan's special command centre against the virus said, according to state broadcaster CCTV.
Earlier, Wuhan cancelled major Lunar New Year events as medical staff handled patients in full-body protective suits and officials used fever scanners to screen travellers.
The World Health Organisation announced on Wednesday it had decided to extend by a day emergency talks on the deadly - postponing its decision on whether to declare a global public health emergency.
