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LostInParadise's avatar

Why did it take so long to think of doing pooled virus testing?

Asked by LostInParadise (29660points) June 26th, 2020

I read that they are thinking of doing pooled testing for the corona virus. What this means is that the blood samples of several people are combined. If the test results are negative then no more testing has to be done for those people. In the worst case, they still have to test everyone in the sample. This could increase testing capacity several fold. This is such a simple idea. Why didn’t you think of it? Why didn’t anyone consider doing this until now?

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10 Answers

Call_Me_Jay's avatar

I read about pooled testing for coronavirus months ago. Here’s one thing I googled up from April.
Testing pooled samples for COVID-19 helps Stanford researchers track early viral spread in Bay Area

janbb's avatar

I assume that’s just testing for antibodies if it’s blood testing?

Dutchess_lll's avatar

I don’t see any benefit. If it comes back positive they have to retest each individual.

Call_Me_Jay's avatar

The benefit is quickly eliminating large groups. Say you have to test 30 people. If the test is negative, 30 are clear and you’re done.

If not divide it again. You might clear 15 more people. Etc, etc.

And you don’t have to draw blood again. You only use a part of each sample for each round.

johnpowell's avatar

This was mentioned a lot on news when this whole thing started. I had just assumed that they were already doing it.

Four months ago it would have helped a lot since not many people had it and you could have batched 50 samples together and could have came back with no positives. But now it seems like it would be less effective since the virus is so widespread.

janbb's avatar

I just read that they’re starting it now. Is it the up the nostril test, does anyone know or a blood sample?

Call_Me_Jay's avatar

Blood sample for antibodies. The nasal swab for virus would not be pooled.

Dutchess_lll's avatar

What are they looking for? An active virus or antibodies? Say they’re looking for active viruses and the pool comes back negative. But the very next day they might get the virus.
If any pool comes back at less than 100% in agreement you have to retest individually.

LostInParadise's avatar

Maybe some numbers will show you the advantage of pooling. I am going to take some numbers out of the air for illustration purposes. Suppose they pool ten people at a time and that the chances of getting a positive result for ten people is ten percent, which means there is a 90 percent chance of getting a negative result.

Without pooling, testing 10 people requires ten tests.

With pooling, there is one initial test and a 90% chance of no additional testing and a 10% chance of doing 10 more tests. That averages out to 1 + 9/10×0 + 1/10×10 = 2 tests per 10 people.

2 tests per 10 people is significantly better than 10 tests per 10 people.

Call_Me_Jay's avatar

What are they looking for? An active virus or antibodies?

Blood tests are for antibodies. Nasal and throat swabs are for viruses.

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