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IT IS more than seven weeks since the , but according to one estimate, had been tested for the infection by 7 March. In contrast, reports suggest that more than .
One reason for the low figure in the US lies in problems with the tests developed by the Centers for Disease Control and Prevention (CDC). Although it sent test kits out to state laboratories on 5 February, it was clear there was a hitch with one reagent used in the test, and many state labs couldn鈥檛 use the kits.
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On its own, this might not have had such a severe impact on testing in the US because, says William Schaffner at Vanderbilt University in Tennessee, government labs can perform only a limited number of tests. 鈥淭hey have a finite capacity, not only in terms of reagents but in terms of personnel to process tests,鈥� he says. Instead, the US healthcare system relies on commercial companies to develop their own test kits and handle the bulk of the demand. 鈥淭hese larger commercial labs are more like factories,鈥� says Schaffner. 鈥淭hey can process many more specimens.鈥�
But commercial tests were also held up. US authorities declared the coronavirus outbreak a public health emergency on 31 January. In those circumstances, testing kits for the virus had to obtain 鈥渆mergency use approval鈥� from the US Food and Drug Administration. This further limited the ability to test for the virus in the US at precisely the time it became urgent and necessary to do so more widely.
. From 29 February, companies were able to begin using their test kits without emergency use approval, providing they intended to apply for it. Commercial tests are now being made available.
鈥淭his will make it much easier for a physician to get a specimen tested,鈥� says Schaffner. However, even if they have health insurance, many people in the US for private sector testing, which could act as a deterrent.
There are other problems. For weeks, the CDC recommended doctors test people only if they had symptoms and or been in contact with someone known to be infected, even though there were already notable outbreaks in other countries. It was only on 4 March that guidelines were relaxed to let anyone get tested 鈥� but reports suggest some people, , were still being refused tests after this date.
There is also concern that, if demand for testing surges, critical test components could become scarce. 鈥淒emand is challenging our capacity to supply certain products,鈥� says Thomas Theuringer at QIAGEN, a firm based in Germany that produces some components of coronavirus tests. He says QIAGEN is ramping up production and hiring new staff to cope.
In the absence of adequate testing, the virus can spread undetected to form new outbreaks. On 8 March, Trevor Bedford at the Fred Hutchinson Cancer Research Center in Seattle published preliminary genetic tests that appear to connect a coronavirus outbreak in Washington state with a case on the Grand Princess cruise ship, which docked in Oakland, California, on Monday.
