Influenza A(H1N1): lessons learned and preparedness

Dr Margaret Chan
Director-General of the World Health Organization

Keynote speech at a high-level meeting on influenza A(H1N1): lessons learned and preparedness
Cancun, Quintana Roo, Mexico

2 July 2009

President Calderon, Minister Cordova, Governor Canto, Secretary Sebelius, Minister Aglukkaq, honourable ministers, distinguished participants, ladies and gentleman,

Let me thank the ministries of health of Mexico, the United States of America, and Canada for organizing this high-level meeting. Our special thanks to the government of Mexico for hosting this meeting. President Calderon, your leadership in managing the H1N1 outbreak in Mexico is commendable.

The fact that we are gathered here in Cancun, Mexico, reaffirms a statement consistently made by WHO since the new H1N1 virus was first detected. Recommendations to avoid travel to Mexico, or to any other country or area with confirmed cases, serve no purpose.

They do not protect the public. They do not contain the outbreak. And they do not prevent further international spread.

We are in phase 6 – that is, we are in the early days of the 2009 influenza pandemic. As we see today, with well over 100 countries reporting cases, once a fully fit pandemic virus emerges, its further international spread is unstoppable.

Influenza pandemics are remarkable events because they spread throughout a world population that is either largely or entirely susceptible to infection. They tend to hit a given area in the epidemiological equivalent of a tidal wave.

In densely populated areas, we see a steep increase in the number of cases, with a sharp peak, followed by a steep decline. Once the virus has swept through a susceptible population, transmission may continue, but at a much lower intensity.

In more sparsely populated areas, the peak may be flatter. Aggressive control measures can also flatten the epidemiological peak somewhat, but only for a while.

Mexico, and especially Mexico City, experienced this tidal wave of cases, and its peak, back in April. Other countries, where the virus was introduced later, are experiencing it now. More countries will see this pattern in the months to come.

But the worst for Mexico should be over now, at least during this first wave of spread. Our presence here is an expression of confidence. Mexico is a safe, as well as a beautiful and warmly gracious, place to visit.

Ladies and gentlemen,

When a new infectious agent causes an outbreak, it is nearly always the first country affected that suffers the most. New diseases are, by definition, poorly understood as they emerge.

The first country affected will, quite literally, not know what hit it in the early days of an outbreak. Decisions, from the doctor at the hospital bed to the head of state, have to be made quickly and decisively in an emergency situation characterized by considerable scientific uncertainty.

Mexico was the first country to experience a widespread outbreak. Mexico bore the brunt of these consequences at a time when the new virus had not yet been identified and nothing was known about the disease it causes.

Mexico gave the world an early warning, and it also gave the world a model of rapid and transparent reporting, aggressive control measures, and generous sharing of data and samples.

Canada and the United States supported the early control measures in Mexico, and then followed this model of transparent reporting and generous collaboration as their own outbreaks began to spread.

WHO and the international community have much to thank these three countries for setting a precedent that, up to now, nearly every country has followed.

Thanks to this collaboration, we have some answers that can help us greatly right now, as countries do everything possible to protect their populations, mitigate the health effects, and prepare for whatever might lie ahead.

What do we know? As I have said before, we have good reason to believe that this pandemic will be of moderate severity, at least in its early days.

We have seen some social disruption, especially when schools or camps have had to close, bringing added demands on parents and their employers. Most health systems have coped well, though some have reported some strains on staff, hospitals beds, laboratories and resources.

But we need to watch very carefully what happens during the current winter season in the Southern Hemisphere.

We are still seeing a largely reassuring clinical picture. The overwhelming majority of patients experience mild symptoms and make a full recovery within a week, often in the absence of any form of medical treatment. Research published last week confirms that this pattern, in which most patients experience mild influenza-like illness, has also been seen in Mexico.

Most cases of severe and fatal infection continue to occur in people with underlying medical conditions. We are getting, day-by-day, better data on the specific conditions that place patients at heightened risk.

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.

But there are some exceptions that must be the focus of particular concern. For reasons that are poorly understood, some deaths are occurring in perfectly healthy young people. Moreover, some patients experience a very rapid clinical deterioration, leading to severe, life-threatening viral pneumonia that requires mechanical ventilation.

In keeping our populations informed, we face a difficult challenge. We cannot be alarmist, as this risks flooding emergency wards with the worried well, creating disruptively high demands for staff, hospitals, and laboratories. I am sure you will agree: health services need to stay fit for genuinely severe cases.

At the same time, if we are overly reassuring, patients in genuine need of treatment, where rapid emergency care can make a life-and-death difference, may be lulled into waiting too long.

Last week, Mexican researchers published clinical profiles of early H1N1 cases in the New England Journal of Medicine. As noted, the full clinical spectrum of this disease is not yet fully understood. We do not fully understand the predictive factors for severe or fatal infections.

However, as more and more data become available, we are getting a better grip on warning signs that can signal the need for urgent medical care. Symptoms of concern include difficulty in breathing, shortness of breath, chest pain and severe or persistent vomiting.

In adults, a high fever that lasts for more than three days is a warning sign, particularly when accompanied by a general worsening of the patient’s condition. Lethargy in a child, that is, a child that has difficulty waking up or is no longer alert, or is not playing, is a warning sign.

For a pandemic of moderate severity, this is one of our greatest challenges: helping people to understand when they do not need to worry, and when they do need to seek urgent care. This is one key way to help save lives.

Ladies and gentlemen,

Between the extremes of panic and complacency lies the solid ground of vigilance. This meeting is all about vigilance: taking stock of what we have learned, and preparing for whatever surprises this capricious new virus delivers next.

Constant, random mutation is the survival mechanism of the microbial world. Like all influenza viruses, H1N1 has the advantage of surprise on its side.

We have the advantages of science, and of rational and rigorous investigation, on our side, supported today by tools for data collection, analysis, and communication that are unprecedented in their power.

We have another advantage on our side, as exemplified by this meeting: collaboration and solidarity. It is my sincere wish that this meeting will take us some big steps forward in building our collective defences against a threat shared by all.

Thank you.