The World Health Organization (WHO) announced it has raised the level of influenza pandemic alert from phase 5 to phase 6, following an emergency meeting yesterday by WHO scientists in Geneva to assess the available evidence on global infections of A(H1N1) swine flu.

WHO Director-General Dr Margaret Chan said:

“The world is now at the start of the 2009 influenza pandemic.”

In an official announcement speech yesterday, Chan commented how this particular A(H1N1) virus, which has not circulated in humans before, emerged in late April, appears to be spreading easily from person to person and country to country, to the extent that barely two months later we now have 74 countries reporting nearly 30,000 lab-confirmed cases of infection.

But this could be a very conservative estimate of the actual spread of the virus because as she went on to explain:

“With few exceptions, countries with large numbers of cases are those with good surveillance and testing procedures in place.”

Also, in several countries, it is no longer possible to trace clearly how the virus has passed from human to human and the WHO experts consider that further spread will be 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,” said Chan, explaining that the evidence available and the assessment of these experts together meets the scientific criteria for an influenza pandemic.

“I have therefore decided to raise the level of influenza pandemic alert from phase 5 to phase 6,” she added.

It is still early days in the progress of the pandemic and the virus is being watched very closely. In fact this is the first time ever that a pandemic has been detected so early or observed so intensely, in “real-time” as it happens.

“The world can now reap the benefits of investments, over the last five years, in pandemic preparedness,” said Chan.

Chan explained that the world is in a strong position, “we have a head start”, she said. But the irony of advanced warning is the risk of worry and panic, and people need to be reassured and advised about what to do, in the midst of early but incomplete and uncertain scientific knowledge about the disease.

The picture, which is currently very patchy, could change at any moment.

“The virus writes the rules and this one, like all influenza viruses, can change the rules, without rhyme or reason, at any time,” warned Chan.

On a global scale, there is good reason to believe that this pandemic, at least for the time being, will not be severe. But, this could change, as it has in the past, and it can vary from country to country.

The vast majority of patients infected so far have had mild symptoms and have made a full recovery, without medical treatment.

And on a global scale, while each and every death to the virus is “tragic” said Chan, the number so far has been small compared to the number of infections.

“However, we do not expect to see a sudden and dramatic jump in the number of severe or fatal infections,” she added.

The Director General summarized what we know so far about the new H1N1 swine flu:

  • It tends to infect younger people: in nearly all areas with large and sustained outbreaks, most cases have been in people under the age of 25.

  • In some areas with large and sustained outbreaks, about 2 per cent of the cases became severe very quickly, progressing rapidly to life-threatening pneumonia.

  • Most of the severe and fatal infections were in people aged between 30 and 50.

  • This is a very different pattern to seasonal flu, where most deaths occur among the frail and elderly.

  • Many, but not all, severe cases appear to have been in people who were already ill or had a chronic condition like asthma, cardiovascular disease, diabetes, obesity and autoimmune disorders. However, this is based on limited, preliminary data.

  • But, importantly, we should note that about a third to a half of the severe and fatal infections have been in young and middle-aged people who were healthy and with no previous medical conditions when they caught the virus.

  • It is clear that pregnant women are at higher risk of complications if they catch the virus, and given its prevalence among younger age groups, this is a particularly worrying pattern.

  • But perhaps the most worrying aspect of this pandemic is that we don’t know how the virus will behave in the developing world. Until now, nearly all cases reported so far have been in comparatively wealthy countries.

Chan said there were two reasons to be concerned about how the virus will affect developing countries based on the evidence so far.

First, 99 per cent of maternal deaths, such as in childbirth or during pregancy, are in the developing world. And second, about 85 per cent of world’s chronic diseases are in low and middle-income countries.

“Although the pandemic appears to have moderate severity in comparatively well-off countries, it is prudent to anticipate a bleaker picture as the virus spreads to areas with limited resources, poor health care, and a high prevalence of underlying medical problems,” warned Chan.

Chan said that countries should be prepared to see further spread of cases, and countries where the situation appears to have peaked should prepare for a second wave.

Health ministries in all countries have now received guidelines on how to protect against the spread of the virus, and countries who have experienced no or only a few cases “should remain vigilant”, she urged.

Countries where the virus has already spread widely should concentrate on managing infected patients, and should not waste valuable resources on testing and investigation.

Chan said WHO has been talking closely with vaccine companies and since production for the usual yearly doses of seasonal flu vaccine are about to complete, this should free up full capacity to concentrate on vaccine making for the pandemic strain.

WHO do not recommend countries to close their borders or restrict travel.

“Influenza pandemics, whether moderate or severe, are remarkable events because of the almost universal susceptibility of the world’s population to infection,” said Chan, who closed her speech with one final comment:

“We are all in this together, and we will all get through this, together.”

Source: WHO.

Written by: Catharine Paddock, PhD