Influenza A (H1N1) pandemic: true or false alarm

摘要

On 24 April 2009 the World Health Organization (WHO) issued an alert about a possible influenza A (H1N1) pandemic-after diagnosing and reporting several cases in Mexico and the USA. WHO declared a phase 3 influenza pandemic alert, and 3 clays later raised the pandemic alert to phase 4. The continuous confirmation of new cases in various countries, mainly in the European Union (EU), required WHO to raise the pandemic alert to phase 5 less than 1 week after declaring phase 3.' On 11 June 2009. WHO declared a phase 6 influenza pandemic alert, which is the maximum alert level.