Medical experts have criticised the Hospital Authority for a lack of urgency over possible disease outbreaks despite the Sars and bird flu crises.
They described the handling of the pneumonia cases as 'too passive'.
'We are only lucky the latest incident has not worsened to become a pandemic,' said infectious diseases expert Lo Wing-lok.
Centre for Health Protection consultant Thomas Tsang Ho-fai admitted on Thursday the centre only became aware of the cases through the media. Yesterday he argued the two cases were isolated and unrelated.
'Pneumonia is a common cause of death as it is the third-biggest killer in Hong Kong,' said Dr Tsang, adding it would be 'sensible' for the Hospital Authority not to report all cases to the centre.
But Dr Lo said: 'When bird flu came in 1997, it also started with a few isolated, seemingly unrelated cases. So did Sars.'