In late April, WHO announced the emergence of a novel influenza A virus.
This particular H1N1 strain has not circulated previously in humans. The virus is entirely new.
The virus is contagious, spreading easily from one person to another, and from one country to another. As of today, nearly 30,000 confirmed cases have been reported in 74 countries.
This is only part of the picture. With few exceptions, countries with large numbers of cases are those with good surveillance and testing procedures in place.
Spread in several countries can no longer be traced to clearly-defined chains of human-to-human transmission. Further spread is considered inevitable.
I have conferred with leading influenza experts, virologists, and public health officials. In line with procedures set out in the International Health Regulations, I have sought guidance and advice from an Emergency Committee established for this purpose.
On the basis of available evidence, and these expert assessments of the evidence, the scientific criteria for an influenza pandemic have been met.
I have therefore decided to raise the level of influenza pandemic alert from phase 5 to phase 6.
The world is now at the start of the 2009 influenza pandemic.
We are in the earliest days of the pandemic. The virus is spreading under a close and careful watch.
No previous pandemic has been detected so early or watched so closely, in real-time, right at the very beginning. The world can now reap the benefits of investments, over the last five years, in pandemic preparedness.
We have a head start. This places us in a strong position. But it also creates a demand for advice and reassurance in the midst of limited data and considerable scientific uncertainty.
....On present evidence, the overwhelming majority of patients experience mild symptoms and make a rapid and full recovery, often in the absence of any form of medical treatment.Worldwide, the number of deaths is small. Each and every one of these deaths is tragic, and we have to brace ourselves to see more. However, we do not expect to see a sudden and dramatic jump in the number of severe or fatal infections.
We know that the novel H1N1 virus preferentially infects younger people. In nearly all areas with large and sustained outbreaks, the majority of cases have occurred in people under the age of 25 years.
In some of these countries, around 2% of cases have developed severe illness, often with very rapid progression to life-threatening pneumonia.
Most cases of severe and fatal infections have been in adults between the ages of 30 and 50
years.
This pattern is significantly different from that seen during epidemics of seasonal influenza, when most deaths occur in frail elderly people.
Many, though not all, severe cases have occurred in people with underlying chronic conditions. Based on limited, preliminary data, conditions most frequently seen include respiratory diseases, notably asthma, cardiovascular disease, diabetes, autoimmune disorders, and obesity.
At the same time, it is important to note that around one third to half of the severe and fatal infections are occurring in previously healthy young and middle-aged people.
Without question, pregnant women are at increased risk of complications. This heightened risk takes on added importance for a virus, like this one, that preferentially infects younger age groups.
Finally, and perhaps of greatest concern, we do not know how this virus will behave under conditions typically found in the developing world. To date, the vast majority of cases have been detected and investigated in comparatively well-off countries. ...
(Source WHO. Excerpted from the Statement to the press by WHO Director-General Dr Margaret Chan 11 June 2009 )
