Last week, in response to the outbreak of a new strain of H1N1 Influenza A centered in Mexico, the World Health Organization (WHO) raised its pandemic threat level to Phase 5, which is characterized by verified human-to-human transmission of a virus in two or more countries, giving a strong signal that a pandemic, or widespread contagion, is imminent.

Within the past several days, a case has been confirmed in Hong Kong (a Mexican visitor), and in South Korea. The first person-to-person transmission of the virus in Asia was confirmed (a nun who met another nun returning from Mexico at the airport in Seoul).

Responding to the threat of pandemics, especially at the beginning of an outbreak, is tricky.