‘Pooled testing’ for COVID-19 holds promise, pitfalls

'Pooled testing' for COVID-19 holds promise, pitfalls

WASHINGTON (AP) — The nation’s prime well being officers are banking on a brand new strategy to dramatically enhance U.S. screening for the coronavirus: combining take a look at samples in batches as an alternative of working them one after the other.

The potential advantages embody stretching laboratory provides, decreasing prices and increasing testing to hundreds of thousands extra Individuals who might unknowingly be spreading the virus. Well being officers assume contaminated individuals who aren’t exhibiting signs are largely liable for the rising variety of instances throughout greater than half of states.

“Pooling would give us the capability to go from a half-a-million exams per day to doubtlessly 5 million people examined per day,” Dr. Deborah Birx, the White Home’s coronavirus response coordinator, instructed a latest assembly of laboratory specialists.

For now, federal well being regulators haven’t cleared any labs or take a look at maker to make use of the method. The Meals and Drug Administration issued pointers for take a look at makers in mid-June and desires every to first present that mixing samples doesn’t cut back accuracy, one of many potential downsides.

So it’s not clear when pooled testing could also be out there for mass screenings at colleges and companies.

The precept is straightforward: As a substitute of working every individual’s take a look at individually, laboratories would mix components of nasal swab samples from a number of individuals and take a look at them collectively. A damaging consequence would clear everybody within the batch. A constructive consequence would require every pattern to be individually retested. Pooling works greatest with lab-run exams, which take hours — not the a lot faster particular person exams utilized in clinics or physician’s places of work.

The thought for pooling dates from World Battle II, when it was thought of for rapidly screening blood samples from U.S. draftees for syphilis. Since then it has been adopted to display blood samples for HIV and hepatitis. And growing nations have used pooled samples to stretch testing provides.

China reported utilizing the strategy as a part of a latest marketing campaign to check all 11 million residents of Wuhan, town the place the virus first emerged late final 12 months.

“Individuals assume that is some new idea as a result of ordinarily we don’t have this problem of getting to stretch testing capability,” mentioned Darius Lakdawalla, a well being economist on the College of Southern California.

Lakdawalla and colleagues estimate that pooled testing may save colleges and companies between 50% and 70% on prices. Beneath their mannequin, a bunch of 100 workers may very well be divided into 20 batches of 5 individuals. Assuming 5% of individuals carry the virus, solely 5 swimming pools would take a look at constructive, requiring particular person testing. Finally, 45 exams could be wanted for the pooled strategy, versus 100 particular person exams.

However pooling gained’t at all times be the most suitable choice. Importantly, it gained’t save time or sources when utilized in COVID-19 scorching spots, comparable to an outbreak at a nursing dwelling. That’s as a result of the logistical and monetary advantages of pooling solely add up when a small variety of swimming pools take a look at constructive.

Specialists usually suggest the method when fewer than 10% of individuals are anticipated to check constructive. About 7% of U.S. exams have been constructive for the virus prior to now week, in accordance with an AP evaluation, although charges range broadly from place to position. For instance, pooling wouldn’t be cost-effective in Arizona, the place a surge has pushed constructive take a look at outcomes to over 22%. However the strategy may make sense in New Jersey, with a positivity charge underneath 2%.

Nebraska’s state well being laboratory used batch testing with particular permission from the governor and the FDA starting in March. The lab’s director mentioned they needed to cease a number of weeks in the past when their constructive charge jumped to 17% with outbreaks at meat packing crops.

“We knew that pooling wasn’t working anymore when these charges began going up,” mentioned Dr. Peter Iwen.

Reserving pooled testing for giant teams with low charges of an infection dovetails with the federal government’s rising deal with individuals with out signs spreading the virus, particularly youthful individuals.

“It’s a extremely good device. It may be utilized in any of plenty of circumstances, together with on the group stage and even in colleges,” Dr. Anthony Fauci, the nation’s prime infectious-disease professional, instructed a Senate listening to Tuesday.

Nonetheless, well being officers might should persuade some key gamers to undertake the strategy. LabCorp, one of many nation’s greatest testing chains, mentioned in an e mail that it’s conversant in pooled testing however at present believes “particular person affected person testing is the best and environment friendly method” to display for COVID-19.

Dr. Colleen Kraft of Emory College worries that batched testing — with its a number of rounds of screening for some sufferers — may gradual take a look at outcomes, a key issue for getting these contaminated into quarantine.

“In case you are attempting to do one thing speedy, this really prolongs the turnaround time,” Kraft mentioned.

She and others even have issues about accuracy, since take a look at efficiency tends to drop when screening in bigger teams of individuals the place the focused illness is much less frequent.

“If we will’t belief the take a look at outcomes then there’s no level in doing the take a look at,” mentioned Jennifer Nuzzo, of the Johns Hopkins College’s Covid-19 Testing Insights Initiative.


Comply with Matthew Perrone on Twitter: @AP_FDAwriter


AP writers Lauran Neergaard in Washington, Nicky Forster in New York and Christina A. Cassidy in Atlanta contributed to this report.


The Related Press Well being and Science Division receives assist from the Howard Hughes Medical Institute’s Division of Science Schooling. The AP is solely liable for all content material.

Supply hyperlink

This site uses Akismet to reduce spam. Learn how your comment data is processed.