A subsequent investigation by University of Hong Kong microbiologist, Yuen Kwok-yung, blamed the mask for the transmission, with Yuen branding the use of such masks ‘a bit selfish’.
The Centre for Health Protection has urged the public not to use valve masks, saying what the wearer breathes out is not filtered.
“If the wearer is infected with Covid-19 or other respiratory diseases, it may increase the infection risks of others nearby,” the centre said.
The centre said people in hotel quarantine should instead wear surgical masks, when checking in – or opening the door of their room – to prevent any virus transmission. It has also asked aircrew and hotel staff to remind those undergoing quarantine not to use valve masks.