H1N1: Overview and perspectives

Abstract

The swine origin influenza virus A/CALIFORNIA/04/2009 (H1N1) was first detected in Mexico and determined the 2009 influenza pandemic. In August 2010, World Health Organization (WHO) declared the beginning of the post-pandemic period. This last pandemic was distinctly different from previous ones. The virus emerged from genetic rearrangement in non-human mammalian host. Moreover, its inter-species transmission is fully reported. However, it affected human population differently from previous pandemic viruses (1918, 1957, 1968), with increased morbidity and mortality among children and young adults. Currently, the virus has a seasonal pattern in the same way as influenza A H3N2 and influenza B, maintaining the same pathogenicity profile, clinical spectrum and sensitivity to antiviral agents. The strain was included in the annual trivalent seasonal vaccine formulation, mainly for risk groups, which are more vulnerable to complications caused by different influenza strains.