In the wake of the Sars outbreak five years ago, the mainland has made significant progress in reporting H5N1 flu incidents promptly. This is evident in the closer communication with Hong Kong health officials and is acknowledged by the World Health Organisation. One of the lessons learned from the painful experience of Sars was that prompt reporting and swift countermeasures are vital if outbreaks of serious contagious diseases are to be contained. Allegations that city officials in Fuyang , Anhui province , covered up an outbreak of a virus that has killed at least 20 young children and infected many hundreds more are, therefore, worrying. The accusations have been made by some state media. Hospitals there began admitting children in early March with symptoms of enterovirus 71, or EV71. But the outbreak was not reported to the public until last Sunday. China Youth Daily has compared the delay with the cover-up of the Sars crisis in 2003. A senior official of the Chinese Centre for Disease Control and Prevention has dismissed the comparison with Sars because that was a deadly new disease that could have infected anyone. If he has a point, he rather undermined it by revealing that the reason for delaying full disclosure of the outbreak for so long was that medical teams were trying to identify the illness and rule out more serious possibilities. No doubt the authorities also hoped to be able to announce that the outbreak was under control. Now they are warning that it could get worse before it gets better. Alerting the public earlier might have made a difference. The mainland outbreak has caused some concern in Hong Kong. A kindergarten here has been closed after twenty-three children developed hand, foot and mouth disease caused by the virus. There is no cause for alarm, as the symptoms usually clear up without treatment. But, especially given the deaths on the mainland, sensible precautions to guard against infection should be taken. There is no room for complacency, either on the mainland or in Hong Kong. Transparency is the key to combating infectious diseases.