Public Warned Against Using 'selfish' Valve Masks

One of the government's advisers on Covid-19, microbiologist Yuen Kwok-yung, has warned against the use of valve masks, after a patient wearing one is suspected to have passed on the virus to another man living next door to him at a quarantine hotel.

The University of Hong Kong professor made the comment on Monday night after inspecting the Regal Airport Hotel in Chek Lap Kok, in which two imported cases recently stayed.

Professor Yuen said the first patient most likely infected the other through airborne transmission, as he was wearing a valve mask - which mainly filtered what he breathed in.

"What's special about these valve masks, is that they are masks that are a bit selfish. In other words, they filter what a person breathes in, but when you breathe out through this valve, it doesn't filter well," he told reporters.

The expert said he has advised airport and quarantine hotel staff to ask inbound travellers with valve masks to change to surgical masks.

He added that the hotel has also made arrangements to improve ventilation in its corridors.