Supplies of a mask widely used during the 2003 Sars outbreak in Hong Kong are running low amid the mystery pneumonia scare in the city, with some retailers doubling prices of limited stocks.At least three online platforms and 15 of the 21 pharmacies contacted by the Post said they had no more N95 respirators, but a doctor assured the public there was no need for panic buying as there was no sign yet of the disease spreading from the mainland Chinese city of Wuhan.As of Monday, 59 cases were…