Summary

Pandemic (H1N1) 2009 poses a serious global health threat. However, the global impact of
this new pandemic remains uncertain. Past pandemics had different impacts on mortality
which varied between countries. Several countries in South-east Asia have already
developed their national pandemic preparedness plans. However, these plans have
focused on surveillance for and response to the highly pathogenic avian influenza (H5N1),
including the rapid containment of H5N1. The newly emerged pandemic (H1N1) 2009 is
different from H5N1 in terms of severity and requires different approaches. There are
several factors that can potentially affect the severity of pandemic (H1N1) 2009, including
a population’s vulnerability and response capacity. The pattern of severity appears to be
changing with the spread of pandemic (H1N1) 2009, which can be conceptualized in a stepwise manner based on observation of the current situation. The overall impact of
pandemic (H1N1) 2009 remains unknown and it is difficult to assess its severity. However,
there is an urgent need to assess its potential severity based on the available data so that
appropriate responses can be provided in order to mitigate its impact