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Swine Flu: The Risks and Efficacy of Vaccines | by DesertRat66 | 2009-10-26 12:30:19 |
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If you work in a hospital it's a good idea. | by vampire | 2009-10-26 12:58:03 |
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Some doctors offices in my area have stopped | by DesertRat66 | 2009-10-26 13:00:08 |
| Here's why the testing has largely stopped: |
by morenna |
2009-10-26 16:49:13 |
1) The only particularly reliable test available at the moment, in terms of both sensitivity and specificity, is an RT-PCR test. Commercial labs are charging $300-400 for this test and there's a 4-6 day turnaround time on the result. The delay in results makes the RT-PCR test useless for clinical decisionmaking since the patient would have either recovered or died before the result came back.
2) Rapid flu tests which detect Influenza A antigen are fairly good at telling you if you're positive, but have a false negative rate of 30-90%, depending upon test kit. (Basically a positive test means you have Influenza A and a negative test means you probably also have Influenza A.)
Regarding reporting:
The *only* thing Public Health is counting is confirmed flu deaths. Novel H1N1 Influenza cases of illness are NOT reportable. Neither are seasonal influenza cases. We are not counting individual Novel H1N1 cases for two reasons:
a. limited resources (I have been getting ~300 lab reports a week across my desk just for flu, plus another 50-100 electronic reports in the reporting system. I am still obligated to investigate cases of the other 50 reportable diseases, most of which are of more concern--shigella, salmonella, cryptosporidiosis.) In addition, collecting case counts for influenza isn't particularly useful for public health interventions. Our local interventions and recommendations aren't based on confirmed cases (we'd get the results too late to be able to change anything), but rather on spikes in absenteeism, OTC drug sales, ER visits, etc.
b. we already know the virus is widespread in the U.S., we don't have the lab capacity to do confirmatory testing on everybody even if physicians were testing, and we do have an influenza surveillance system in place to monitor the situation.
ILI-Net
ILI-Net is the Influenza-Like Illness Network. Specific physicians/medical practices across the U.S. participate in this surveillance program. Two days a week (Mon and Wed where I am) they collect nasal swabs from *all* patients who come to the clinic on that day. These specimens are tested using RT-PCR, the data are aggregated at the state-level and reported to CDC. The ILI-Net physicians also use a CDC website to report how many patients present to their clinic each week with Influenza-Like Illness (defined as fever of >=101 deg F plus cough and/or sore throat).
ILI-Net gives us an idea of what viruses are circulating in the US. Right now 98-99% of the virus circulating in the U.S. is the 2009 Novel H1N1 Influenza Virus (aka Swine Flu). There are occasional seasonal flu viruses being picked up, but rarely. So if you remember back to the rapid flu test I mentioned three pages ago that detects Influenza A, a positive Influenza A test right now is nearly always going to be Novel H1N1 (it's an Influenza A virus).
(I dunno if that answers any questions or if it just confuses things more. Plz ask more questions if the latter occurred. I may or may not be around much longer this evening. Feel free to send e-mail msmorenna with the geemail service.) |
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