The move from pandemic phase five to phase six has been prompted by the continuing human-to-human transmission of the influenza A (H1N1) virus right across the globe.
There has been a particularly sharp increase in the number of new cases of the pandemic flu in Australia and in Chile.
This reflects the fact that it is the winter flu season in the southern hemisphere with environmental conditions conducive to the spread of influenza.
The move from phase five to the declaration of a full pandemic means that the response of health professionals will now be focused on mitigating the effects of the rapidly spread virus in the community. It is an acknowledgment that the policy of containment is no longer viable.
Mitigation aims to reduce the severity of the epidemics peak in an effort to reduce the burden of disease on the healthcare system.