The onion strikes back: Maggie Koerth on the nested problems of Covid-19 testing

Covid-19 testing has been a mixed bag: Singapore and Korea seem to have been able to get on top of things quickly, while the UK and US (to pick too) have – at least in comparison – seemed barely able to get their act together at all.

Maggie Koerth‘s discussion of the issue with Kevin Kelly and Mark Frauenfelder points out that the problem isn’t a technical or scientific one at all – the scientific competence required to do the test is readily available in all of these countries.

The bottlenecks that prevented a faster scale up of testing existed somewhere else in a chain (“Onion“) of nested problems:

.Maggie Koerth: .. What it was that was slowing everything down was shortages in the reagents, for the most part, and also the swabs, actually, because it turns out that most of the world’s swabs were being made in Italy, and that supply chain got hit early on.

Kevin Kelly: So what was Korea, when they were doing – very early on – 10,000 tests a day, what were they using, where did they get their swabs from, why did they have so many tests available at that time?

MK: So a big part of this is that they had been through SARS, and they had had this brush with MERS a few years ago – these are these viruses that are relatives of Covid – so because of that they’d put together this really big stockpile of these important testing ingredients, knowing that things were going to come back and they were going to need this again and they were going to need a lot of it. So when they needed the test they weren’t waiting for things to show up – they had it all.

Whereas the US system, a lot of our health system has gone to this just in time supply chain where having excess around is waste, so we didn’t have more than we needed – until we needed more than we had.

KK: So what were they actually testing in those tests?

MK: Basically all of these diagnostic tests are pretty similar. They’re all basically a PCR test that is taking RNA from the virus and turning into DNA and replicating the DNA.

What the difference is between the WHO based tests that South Korea was using and the CDC test we were using early on is basically in terms of what little snippets of the virus the whole system is set up to look for. So you take these little snippets, and they’re called primers. And when you’re copying the DNA… these little primers will only grow it if they find that little snippet of the virus DNA, so that’s how you make sure that you’re only growing Covid, you’re not growing something else.

So the CDC and the WHO tests use different primers. And from talking to experts about this, there’s wasn’t any better than the CDC’s in terms of the primers, the real big difference was that they had the supplies to actually do it, and they had the network of testing centers ready to go and we did not, and that made a huge difference in what they were able to do.

Maggie Koerth on Cool Tools #226

Often – most of the time? – the technical solution is only a small part of a whole system needed to bring about change.

See also:

The Wrapper
Bill Gates’ Onion
Nested Problems, Nested Solutions

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