Paradigm Shift Intervention Monitoring
Commentary
New
York Confirms Swine
H1N1 High School Spread
Recombinomics Commentary
14:39
May 10, 2009
Today I have the results of New York City specimens in that batch, which include 75 patient specimens from New York City now confirmed with H1N1. Fifty of these 75 cases, or over 65 percent, have a direct link to the St. Francis School outbreak, and represent students and faculty there.
The remaining 25 cases involve children under high-school age and could represent siblings of the St. Francis students, but that cannot be fully determined until the epidemiological investigations are completed.
Because these specimens are from the first days of the outbreak in New York State more than a week ago, they do not indicate active cases, and we believe these individuals have fully recovered. However, we felt it important to brief you on the results of the large batch of older specimens from North Shore-LIJ, as these numbers when added to our current map graphic on our web site will indicate a rather substantial jump in the overall New York City cases.
At this point in the outbreak, reporting daily numbers of new cases is not important because the illness continues to be mild to moderate, similar to seasonal influenza. The numbers are also not particularly significant because they only represent lab-tested specimens, and many individuals with mild symptoms do not go to a physician or hospital, but instead, recover at home - as has been our advice for some time.
As we go forward, the focus of our monitoring and reporting will be more on identifying new locations, trends, and patterns of the H1N1 virus, as well as watching for more severe disease. The test results from the North Shore-LIJ specimens will help us to better understand the early phase of H1N1 in New York and how it has spread geographically over time.
As I mentioned earlier, we are entering a new phase in our response to this outbreak, and Governor Paterson has asked that I only provide updates when there are important new developments.
The above comments from the State of New York swine flu website confirm the spread of H1N1 in the Queens high school last month. Although only 25 students vacationed in Mexico, on April 23 and 24 there were 150 students with flu-like symptoms. 28 were initially confirmed and 17 were suspect based on lab results. The number of cases created a backlog, and the results have now been released for the samples collected last month.
However, there is concern that the swine H1N1 is still silently spreading (see updated map), because the vast majority of cases are mild, and require enhanced surveillance for detection, although a simple influenza A test will be more predictive of swine flu as the seasonal flu season ends in the northern hemisphere.
The above announcement by the NY lab has been echoed across the country. The testing will be selective, and a complete picture of the H1N1 spread will be lacking. This focus on the more severe cases mimics confirmations in Mexico, where the lab confirmed cases significantly underestimates the level of infections.
The focus on severe cases increases the case fatality rate. In the US there have been three reported H1N1 deaths and there has also been a death in Alberta , Canada, raising concerns that the number of fatal infections will climb significantly over the near term.
The identity between H1N1 in Mexico and the US (as well as all other countries submitting sequence data - see list of isolates here), raises concerns that the silent spread will produce frequent co-infections between swine and seasonal H1N1. These co-infections can produce genetic exchanges between human and swine isolates via reassortment and recombination.
This type of rapid genetic evolution between human and swine H1N1 raises concerns that a more virulent H1N1 will emerge in the near term, and lead to a significant rise on severe cases in the fall, when the flu season begins in the northern hemisphere.
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