The Associated Press reporter Mathew Perone writes” The nation’s top health officials are banking on a new approach to dramatically boost U.S. screening for the coronavirus: combining test samples in batches instead of running them one by one.” Its main benefit include economizing laboratory supplies thus reducing costs of testing and testing millions more samples who may unknowingly be spreading the virus.

The idea for pooling dates from World War II, when it was considered for quickly screening blood samples from U.S. draftees for syphilis. Since then it has been adopted to screen blood samples for HIV and hepatitis. And developing countries have used pooled samples to stretch testing supplies.

The Associated Press

The Washington Post describes the testing process this way: “Samples from, say, 20 people are combined into a single pool. One coronavirus test is used on the entire pool. If the test comes back negative, researchers know they can move on to another pool of samples. If it comes back positive, only then would each individual be tested.”

In Scientific America, science journalist Marla Broadfoot writes: “Group testing is a numbers game. Let’s say you are examining 100 people, and one of them is positive. Normally you would do 100 diagnostic tests, searching for genetic material from the virus in each individual. But with group testing, you can divide those 100 people into five groups of 20. That gives you five pools with 20 samples, and you use one test per pool. If the first four sample pools test negative, you have eliminated 80 people with four tests. If the last pool tests positive, you retest each sample in that last pool individually to identify the one with the disease. In the end, you did 25 tests instead of 100.”

If you look around the globe, the way people are doing a million tests or 10 million tests is they’re doing pooling,” Birx said during an online conference of the American Society for Microbiology. Pooling would give us the capacity to go from a half a million tests a day to potentially 5 million individuals tested per day by those poolings.

Deborah Birx, White House Coronavirus Response Coordinator (source: CNN)

• The Trump administration is eyeing a new testing strategy for coronavirus, Anthony Fauci says
• Coronavirus Test Shortages Trigger a New Strategy: Group Screening
• What is pool testing and how does it work?

“But pooling won’t always be the best option. Importantly, it won’t save time or resources when used in COVID-19 hot spots, such as an outbreak at a nursing home. That’s because the logistical and financial benefits of pooling only add up when a small number of pools test positive” writes AP’s Perrone.

Testing Milestone in Minnesota

Gov. Tim Walz announced in his press briefing on Monday that now Minnesota has reached the capacity to run 20,000 covid-19 tests in a single day. “The announcement marks a milestone in the state’s ‘moonshot’ fight against the coronavirus” said Gov Walz.

“The development puts the state in position to understand how prevalent the virus is in Minnesota — which will be the only way to control the virus until a vaccine is available”.