Fauci hints at new approach to COVID-19 testing

Anthony Fauci, the nation’s top infectious disease doctor, said federal health officials are considering a new strategy for coronavirus testing as cases spike in states across the country.

Fauci told The Washington Post in an interview Thursday night that officials are having “intense discussions” about adopting a technique known as pooled sampling — grouping together multiple individuals’ COVID-19 tests to boost testing capacity.

Under this approach, if the virus is not detected in a combined test tube, all the patients can be deemed negative; if it comes back positive, each sample is tested individually.

“What you need to do is find the penetration of infected people in your society,” Fauci said. “And the only way you know that is by casting a broad net.”

A series of studies since April have pointed to the technique’s effectiveness in detecting COVID-19. A peer-reviewed simulation published Tuesday in JAMA Network Open found that pooled sampling could reduce the number of tests required by up to 84 percent, as long as it is deployed in locations with relatively low disease prevalence.

The technique of pooling samples of multiple patients — usually between five and 20 — was pioneered to combat a syphilis outbreak during World War II and has since been used in testing for HIV, hepatitis B and C, and other viruses.

Fauci’s remarks came the same day that the U.S. set a new daily record for coronavirus cases. His comments also followed an announcement that the White House coronavirus task force will hold a press briefing on Friday, its first in roughly two months.

Fauci, a member of the White House coronavirus task force, said at a congressional hearing that testing for COVID-19 is ramping up, despite comments from President Trump last weekend that he ordered testing to be slowed down. Trump said Thursday that he made the comment “jokingly,” after saying earlier in the week that he doesn’t joke about testing.

The U.S. conducted 637,587 tests Thursday, according to the COVID Tracking Project. City officials in Wuhan, China said they conducted 1.47 million tests in a single day last month using pooled sampling.

“Pooling would give us the capacity to go from a half a million tests a day to potentially 5 million individuals tested per day,” Deborah Birx, another member of the White House task force, told an American Society for Microbiology virtual conference this week.

Testing for COVID-19 requires two kits — fan extraction kit to take a sample from a patient, often through a nasal swab, and a kit used in a lab to detect the virus.

Early in the outbreak, the U.S. faced shortages of both types of kits. Pooled sampling addresses shortages in the second type of kit by allowing samples extracted from multiple patients to be tested together in the same test tube.

The technique has not been widely adopted in the U.S. due to regulatory hurdles and concerns over false negatives. Several peer-reviewed studies have identified the conditions in which pooled sampling can be safely deployed to detect COVID-19, saving significant time and testing material.

The Food and Drug Administration (FDA) has not officially authorized the technique, though it loosened guidance on June 16 to make it easier for labs to apply to use it.

Adm. Brett Giroir, assistant secretary for the Department of Health and Human Services, said on a call with reporters Wednesday that his agency is working to provide the FDA with additional data on the technique that could lead to a broader authorization for its use. 

The JAMA Network Open paper published Tuesday found that pooled sampling was more efficient and cost-effective than individual testing as long as the disease prevalence stayed under 30 percent. 

With a low disease prevalence of 1 percent, only 16 percent as many tests would be required as individual testing, according to the simulation.

Alhaji Cherif, a researcher at the Renal Research Institute in New York City who co-authored the paper, wrote in an email that these results show pooled sampling could be deployed in specific scenarios where the need for tests is high, but expected disease prevalence is low.

“The strategy can be very useful and cost-efficient in natural group settings, for example, in first responders, shift workers, classrooms, hospital departments, local clusters, households, conventions and events, long-term care facilities, to name but a few,” Cherif wrote. 

Studies in Germany and Israel have also supported the technique’s efficacy at detecting COVID-19. 

Before individual testing for COVID-19 became standard in the U.S. in late February, researchers at Stanford’s Clinical Virology Laboratory used pooled sampling to test nearly 3,000 patients in the Bay Area despite scarce testing kits.

The updated FDA guidelines issued earlier this month included a procedure for labs to internally validate that a testing kit already approved under the FDA’s Emergency Use Authorization is compatible with pooled testing.

“The steps taken today by the FDA further demonstrate how we are proactively working with diagnostic test developers to facilitate new approaches and get more tests to more Americans more quickly,” the FDA wrote in a statement issued with the updated guidelines.

Rep. Max Rose (D-N.Y.) wrote letters to Giroir, Veterans Affairs secretary Robert Wilkie, and New York governor Andrew Cuomo June 19 urging them to start using pooled sampling. 

“Pooled sampling can be a game changer to get large numbers of people tested quickly –including for nursing homes, hospitals, businesses, and public housing among many others,” Rose wrote in the letters to Giroir and Cuomo. “For businesses of all sizes, this can help them reopen and stay open knowing they can test workers in large numbers and on a regular basis if needed.”

Updated at 10:49 a.m.