CDC Weekend Briefing

Dr. Anne Schuchat: "We expected more cases, and we continue to find them." Despite reports about a decline in cases, the US is still seeing an increase in cases and it does not seem as though the US has hit its peak.

Cases Confirmed: 2254 cases
Hospitalized: 154 (many have underlying conditions)
Deaths: 2 (Texas)

Extended Q&A:
Is this an Epidemic?
A: CDC compares seasonal flu and hospitalizations to surveillance data to determine if there are enough cases to consider it an epidemic of seasonal flu. The ILI diagnoses are going above the threshold we would normally see at this time of the season, but it is still not above the "epidemic threshold". In particular, there has not been an increase in mortality data.

Antiviral Therapy & CDC Guidance:
Antiviral therapy needs to be reserved for those with the most severe illness or underlying medical conditions. Most people have a self-limited infection, spending a few days at home and self-treating is sufficient. Antivirals should be used for treatment (of specific cases) not prevention, as resistance to the antivirals is a concern given the fact that seasonal influenza rapidly developed resistance to these antivirals. Though CDC is not yet seeing H1N1 resistance to antivirals.

Virulence
Virulence markers characterized in the 1918 strain, the 1957 strain, and the H5N1 (bird flu) strains which cause concern about severity of illness and high mortality have not yet been found in the H1N1 strain. "But remember the first strain in 1918 was fairly mild, and it was the second and third waves that were so devastating," Dr. Schuchat.

Circulating Strains of Influenza and Risk of Virus Reassortment
**There are continued seasonal influenza cases which do account for many of the people seeking treatment for ILI. Having both strains circulating at the same time does increase the risk of reassortment and mutation of the H1N1 strain.

"One of the biggest problems with influenza is it's ability to reassort and recombine. So because of that, it is problematic that we're seeing circulation of seasonal flu, H1N1, and, in some countries, H5N1 (avian influenza) at the same time" ... That is why it is so important for countries to have "strong capacities to deal with influenza and have systems in place to look at what happens at the interface between people and animals", Dr. Schuchat**

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CDC is encouraging trackers of seasonal and H1N1 flu to begin referring to the seasonal flu surveillance database: http://www.cdc.gov/flu/weekly/fluactivity.htm
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