Influenza A(H1N1)pdm09: beyond the pandemic.

On August 2010, the World Health Organization declared the end to the 2009 A(H1N1) pandemic. However, influenza A(H1N1)pdm09 continues to circulate as a seasonal virus. Different viruses have predominated in different parts of the world. To date, influenza A(H1N1)pdm09 has demonstrated little antigenic drift, and its oseltamivir resistance has remained low. In some countries, a higher number of severe cases of influenza A(H1N1)pdm09 infection were documented during the 2010-2011 season than during the pandemic period. In addition, delays in oseltamivir administration, higher ages and comorbidities and low vaccination rates in patients with influenza A(H1N1)pdm09 infection were found during the first postpandemic season. Therefore, physicians should carefully consider the pandemic virus as a possible causative agent in patients with influenza-like illnesses admitted to emergency departments. In addition, surveillance systems and vaccination campaigns should continue after the pandemic period.