Coronavirus (Covid-19) pool testing: While some NYC laboratories reduce turnaround time with pool testing, others remain sluggish

Filed Under: Providers

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In April, New York City was the epicenter of the Covid-19 pandemic. Refrigerated trucks waited outside hospitals to receive bodies. Ambulances waited in line at overwhelmed emergency rooms.

Now, with the curve crushed in New York, residents are waiting for their Covid-19 test results.

Partly because resources for testing are being sent to new hotspots of the pandemic, New Yorkers are waiting longer for their results. The median wait times at certain testing locations was nine days in mid-July, according to The New York Times. As Clear Health Costs reported, CVS took 13 days to return results to one Long Island resident.

Different testing locations have different wait times for results. (To get tested herself, CHC’s own Molly Taft tracked down which testing location was fastest. You can read about what she found here.)

The Wall Street Journal reported that wait times in New York City have been cut in half since mid-July (when wait times seemed at their longest) — now down to a median of two days — partly thanks to a technique called pool testing.

Pool testing involves combining samples from multiple patients and testing them together in one tube. If the results are negative, then doctors know that all of the patients in that pool are negative. If the sample is found to be positive, the doctors test each patient within the pool individually. This strategy has been used to test for diseases in blood banking in the past.

Pool testing uses fewer resources and saves time. While some laboratories in the New York area have begun using pool testing, others have not. Some say that the latter are driving up wait times in the city.

A tale of two laboratories

BioReference Laboratories, a national commercial laboratory, processes tests for New York City Health and Hospitals. BioReference began using pool testing in July, and they currently have wait times of two to three days.

Quest Diagnostics processes samples for CityMD, an urgent care chain in New York and New Jersey. CityMD has over 100 locations, the majority of which are in New York City, according to its website. Quest Diagnostics handles a significant portion of the city’s samples, processing 26 percent of tests in the New York City, according to The Wall Street Journal.

Quest Diagnostics has an average wait time of five days, but this is down from prior weeks. An update on the company’s website in July said that the average wait time was seven days, and admitted that some patients will have to wait as long as two weeks. The commercial laboratory is yet to adopt pool testing at its Teterboro, New Jersey laboratory (which processes tests for New York City).

Avery Cohen, a spokesperson for Mayor Bill De Blasio, told The Wall Street Journal that Quest was “the outlier that is driving the average up” for test result wait times.

Notably, Quest has already received Emergency Use Authorization from the Food and Drug Administration for pool testing in its laboratories — it was the first laboratory in the country to receive national approval. Quest has only expanded pool testing to three laboratory locations in Marlborough, Mass., Chantilly, Va. and San Juan Capistrano, Calif., according to a spokesperson.

“We’re working to bring [pool testing] up as quickly as possible,” the spokesperson said in an email to Clear Health Costs. The spokesperson could not provide a timeline for when Quest will expand pool testing to other locations like the one in New Jersey.

The impact of pool testing

One study from the University of Nebraska Medical Center found that researchers could expand testing capacity by 133 percent by using pool testing.

Dr. Baha Abdalhamid, an author of the study, told Clear Health Costs in an interview that pool testing also saves time in processing samples. In their study, he and his colleagues found that pool testing reduced processing time for tests by nearly 40 percent. In practice, Dr. Abdalhamid said, this means that patients get their results sooner.

But, according to Dr. Abdalhamid, there are limitations on the usefulness of pool testing. Whether or not pool testing is effective depends on the incidence rate, or rate of infection, in the population being tested. In Nebraska, where the study was conducted, there was an incidence rate of around 5 percent. Dr. Abdalhamid said that pool testing would not save resources if the population incidence rate was above 10 percent.

That means that New York, where Covid now has a low prevalence, is a prime location for pool testing. Meanwhile, states like Florida and Texas, where transmission is rampant, would not be good candidates.

Dr. Abdalhamid said that, if feasible with the rate of incidence in the community, every laboratory should be using pool testing. “It’s a very effective, straightforward approach,” he said in an interview. “It’s an achievable method.”