The H1N1 influenza outbreak, which began in April 2009, was marked by controversies over whether the World Health Organisation (WHO) and public health authorities had exaggerated the risks of H1N1 and created unnecessary alarm by declaring it a 'pandemic'.

The WHO has also been criticised for its pandemic alert system that focuses on geographical spread of the outbreak rather than its severity, and on alleged conflicts of interests between health officials and experts and vaccine makers.
Reacting to these criticisms, WHO announced it will conduct a review that will examine how well the WHO and its 193 Member States prepared for and responded to the H1N1 outbreak, whether the risks were fully understood or exaggerated and poor countries' access to vaccines.

About 17,000 people have died from laboratory-confirmed cases of H1N1 but the WHO together with other experts say the real death toll is many times higher and it is unlikely that the pandemic declared in June 2009 is over.
It remains unclear whether H1N1 has been more deadly than seasonal flu, which kills thousands of people each year, but it is clearly milder than some of the 20th century pandemics in which millions died.

The virus has subsided in North America, where it originated last year, and in Europe, but there is increased activity in Southeast Asia, West Africa, and Central and South America as the southern hemisphere enters its winter.
The WHO is continuing to ship donated vaccines to poor states in a complex operation, and has now reached 25 developing countries.
The review, starting in April 2010, will be conducted by 29 experts, drawn by WHO regional offices from a pool of scientists and public health officials nominated by Member States.

WHO Director-General Margaret Chan will report their preliminary findings to the WHO's annual World Health Assembly in May, with the final report due to be ready for the 2011 World Health Assembly.