Media Briefing: Influenza A (H1N)
(Conducted by Dr. Jon K. Andrus, Pan American Health Organization, May 7, 2009)
Good afternoon. Welcome again to all members of the Press who are on the line, and thank you again for taking the time to listen to today's briefing by the Pan American Health Organization on the Influenza A (H1N1) epidemic.
- Today, the two burning issues that I am going to cover are: disease monitoring and surveillance, and PAHO's approach to ensuring a sustainable vaccine supply chain to member countries of the Region.
- First, as countries of the Southern Hemisphere enter their winter season, it is clear to us that they are taking the necessary measures to strengthen and enhance their monitoring and surveillance activities.
- Monitoring the evolution of this outbreak in the Southern Hemisphere is of critical importance, not only to determine where the disease is spreading and if our interventions are working, but also to ensure that current profile of disease severity is not changing.
- The diagnosis of influenza on the basis of clinical symptoms and signs alone is difficult and not very accurate. Rapid diagnostic tests are available that in some cases can help clinicians decide whether or not to place a patient on antivirals early in the course of the illness, but generally these rapid diagnostic tests are not very accurate, perhaps have a only 60% sensitivity. So PAHO is not recommending use of these rapid tests in this outbreak.
- One thing that is important to understand when first identifying cases, is to note the presence of fever. Fever >38% occurs in the vast majority of confirmed influenza cases. Approximately 6-48 hours after the onset of fever, then other symptoms kick in, like cough, nasal congestion, and sore throat. The cardinal sign in acute influenza is fever, as I mentioned. A lot of patients can even remember the hour when they became ill because the infection comes on so acutely. On the other hand, the common cold comes on gradually, and low-grade fever may or may not be present. Let's come back to this point when we talk about specimen collection procedures that PAHO is currently recommending.
- From a day before the onset of fever, the virus can be found in the nasopharynx and throat, with highest viral shedding when the fever peaks, or within the first 4 days or so of illness onset.
- Testing of nasopharyngeal specimens by polymerase chain reaction in countries is accurate and being done. The collection of nasopharyngeal swabs also provides an opportunity to isolate the virus and conduct more sophisticated analyses like genomic sequencing of the viral genome. Such work also helps us monitor whether the virus is mutating over time, with possible implications on disease severity. Therefore, the preferred specimen to be collected is most definitely the nasopharngeal swab.
- Countries have been provided with PCR testing kits from the CDC. Such kits allow the country to determine if a suspect case with influenza-like illness is indeed positive for the presence of influenza A virus. Early in the outbreak, such specimens are sent to CDC for confirmation that influenza A virus is indeed the current H1N1 subtype causing this outbreak. Once the outbreak spreads, we are seeing that 99% of the probable cases end up being confirmed as H1N1.
- Related to this, we are advising all countries not to collect specimens from patients who do not have the cardinal sign of fever. It is very unlikely these cases are infected with influenza A (H1N1) virus. So, we really want to prevent overwhelming our laboratory capacity with unnecessary specimen collection. This is also very important information for individuals and families with their understanding of this infection.
- Second, I would like share with you a few points about the back ground of the Pan American Health Organization and its Revolving Fund for vaccine purchase. PAHO was founded in 1902 to confront the scourge of yellow fever. At that time epidemics periodically swept across the Region, particularly in warmer climate countries. The case fatality rate of this disease can be as high as 40% during epidemics. With this current crisis brought on by the Influenza A (H1N1) virus, PAHO's response is grounded in the same guiding principles of equity and access that helped prevent and control the multiple yellow fever outbreaks that occurred in the early half of the last century.
- We are fortunate in the Americas to have the PAHO Revolving Fund for vaccine procurement, particularly if a pandemic vaccine becomes available.
- Thanks to the genius of Dr. Ciro de Quadros the guiding principles of the Revolving Fund have enabled PAHO to repeatedly respond to crises over the years, such as the one we are now experiencing. For 30 years PAHO has been managing this fund to ensure a sustainable supply chain of vaccines to our member countries. At present, 30 countries across the Region use the Revolving Fund to secure their supply of seasonal influenza vaccines.
- We are not a vaccine supplier, that is we do not make the vaccine, but on behalf of member countries we procure and provide sustainable vaccine supply chain. We are taking all steps humanly possible that will ensure that we maintain that track record of service to Member Countries in confronting this crisis.
- Third, we need to keep reminding ourselves that this outbreak is still in the early stages of development, and we cannot predict the UN-predicable. So we must remain vigilant. If we alert people as we have, and this pandemic fizzles out, that would be great. But, we just don't know.
- Again, we call upon all individuals, all families, all communities, and all governments to stay focused on all the actions that go into preparation and prevention.
Let me stop there to address any questions that you may have. Thank you.