The World Health Organization (WHO) Director-General Dr Margaret Chan announced on 10th August 2010 that the H1N1 influenza virus has moved into the post-pandemic period. This followed advice from the members of the WHO Pandemic Emergency Committee convened under the International Health Regulations which had met for the ninth and last time earlier that day. For a report of the Emergency Committee meeting click here. A recording and transcript of the press conference at which Dr Chan made the announcement is also available on the WHO web-site.
This decision and announcement were based on the definition of post pandemic period in the 2009 WHO pandemic guidance “Levels of influenza activity have returned to the levels seen for seasonal influenza in most countries with adequate surveillance” and comparison with repeated reviews of the current epidemiological situation. These assessments undertaken by WHO (latest August 6th) have indicated that in most countries where there has been surveillance for some years influenza activity has indeed returned to levels of transmission that are normally seen for the previous seasonal influenza. ECDC has been undertaking its own independent assessments paying particular attention to what is being seen in the Southern Hemisphere temperate countries with on-going surveillance which are now experiencing their winter (Argentina, Australia, Chile, New Zealand and South Africa) as that will also be the best indication of what can be expected in the European Winter of 2010/2011. The latest ECDC review for those five countries was published on July 30th and these data were considered by a re-convened meeting on July 29th of EU experts under ECDC’s Advisory Forum (July 29th) that oversaw its earlier forward look Risk Assessment. Essentially the data reviewed by ECDC gave the same analyses as those of the WHO Emergency Committee.
WHO has published a series of anticipated Questions & Answers relating to the post-pandemic period, along with recommendations to be taken into account by the countries’ Health Authorities during the present post-pandemic period which help, not only health authorities and governments public health heads but also the general public, to understand the significance and implications of this new period of the 2009 influenza A(H1N1) pandemic just begun.
WHO points out that in the post-pandemic period, localized outbreaks of different magnitude may show significant levels of transmission of 2009 influenza A(H1N1) and other influenza viruses and that is being observed now in the Southern Hemisphere temperate countries. However, very few out-of-season outbreaks are being reported in the Northern Hemisphere and there is hardly any transmission in Europe at present – see latest ECDC Report dated July 30th. Southern Hemisphere temperate countries and the tropical countries, where transmission is taking place, are reporting a mix of influenza and other respiratory viruses though not the old seasonal A(H1N1) (see latest WHO report). Finally, WHO advised that those groups identified during the pandemic as being at higher risk of severe or fatal illness will probably remain at heightened risk, though hopefully the number of cases of severe infection will diminish.