Published: August 5, 2009
As the swine flu spreads, many doctors and hospitals are turning to rapid tests that can determine within minutes whether an anxious patient has the flu. Sales of such tests are soaring.

Dr. Christine Ginocchio, of the North Shore-Long Island Jewish Health System, whose research showed a flaw in rapid flu tests.

But the tests have a severe limitation: They may fail more than half the time to detect swine flu infections, according to newly published studies and to experts in medical testing.

The low sensitivity of the tests is becoming a concern to health authorities because a false negative reading might prompt a doctor not to prescribe antiflu drugs.

It is also one of the big issues laboratory directors face as they prepare for what is expected to be a crush of flu testing this fall and winter. Numerous diagnostics companies are hoping to capitalize on demand for influenza testing.

The rapid tests “are missing a ton of flu,” said Christine C. Ginocchio, director of the division of microbiology, virology and molecular diagnostics at the North Shore-Long Island Jewish Health System in Lake Success, N.Y.

For seasonal flu, experts have long known about the low detection ability of the rapid tests. The new studies suggest the tests are no better, and possibly worse, at detecting the swine flu strain now spreading around the world, known formally as the novel H1N1 virus.

In a study published recently in The Journal of Clinical Virology, Dr. Ginocchio found that one rapid test detected only 10 percent of the swine flu infections that could be picked up by a more sophisticated laboratory culture. A different rapid test detected 40 percent. (Dr. Ginocchio is a consultant to Luminex, a company that makes a more accurate but slower test.)

The federal Centers for Disease Control and Prevention said Thursday that in its own study, three rapid tests detected 40 to 69 percent of the swine flu cases. The rapid tests performed better on the seasonal flu, picking up as many as 80 percent of the cases.



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South Africa
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United Arab Emirates
•  Hospitals warned on reporting swine flu  (Link)

United Kingdom
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•  Vietnam flu total tops 1000 (Link)

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