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Testing for COVID-19 has dropped 30% at commercial labs in the last week: Politico; self-collected samples could help


Coronavirus by Engin Akyurt via (open access)

Politico reported on April 14 that lab testing for the novel coronavirus has dropped in the last week, as follows:

American Clinical Laboratory Association reported that the number of samples commercial labs handle each day fell from 108,000 on April 5 to 75,000 by April 12. The group’s members, including commercial giants Quest and LabCorp, analyze about two-thirds of all coronavirus tests in the U.S.

Reasons for the drop in testing are complex.  One is the testing criteria by the CDC, which prioritize sick people in hospital and healthcare workers who are ill.   The criteria have not been changed recently, but they de-emphasize less seriously ill outpatients.  Many hospitals are full and emergency rooms overflowing, while others have closed down due to employee illness or budget shortfalls. There are three levels of priority, first seriously ill inpatients and healthcare workers, second people in long term care facilities with symptoms and those over 65 or with chronic conditions with symptoms and ill first responders, and third people in critical infrastructure work with symptoms, and so on. Those who just want to be tested without symptoms are not considered a priority, that is they can’t get tests.  You can see CDC’s criteria here.

Public health labs, which do a smaller proportion of tests, said that they have not noticed a drop in test requests, but they do not keep figures on this subject.

Another problem for testing is spot shortages of test swabs and other parts of the test kit.  Protective equipment for those who perform tests are also in short supply.

Wyoming’s health labs reported reducing the number of tests because of a shortage of reagents used to do the actual test in the lab.

This drop in testing comes as the case numbers have exploded.  I won’t give the latest figures but you can go to Johns Hopkins for the numbers.

Meanwhile, a preprint study on MedRxiv from April 11 showed that self-collected samples performed as well as samples obtained by clinicians swabbing the nasopharynx in detecting active virus shedding.  Self-collected testing could reduce a number of problems with using personal protective equipment while obtaining specimens and increase sample collection.  Oral saliva and sputum collection could save on swabs as well.

This morning, I saw on TV a report sourced from the New York Post (a rag I don’t read because of its pro-[redacted] bias) that New Jersey has opened a new parking lot test site that uses saliva samples collected by patients, presumably in their cars.  Here’s hoping that this newer form of testing will be widely adopted.  It is better for two reasons: first, no swabs are needed, and second, interactions with health-care providers are greatly reduced.

I don’t need to tell you that this means trouble for the hopes to “re-open America”.  There has been a slight drop in the last week in the rate of new cases, and the rate of testing may be to blame.  We can’t deal with this pandemic if we don’t get numbers on how many people have been infected.

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