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Are there countries who conduct serologic tests? PCR tests (widely used?) wouldn't catch people who got the infection, developed antibodies with no or mild symptoms, but didn't transmit the virus around at the moment test is taken.

From the article about Covid-19 serologic test development:

> The serologic tests, which are different from the ones used to diagnose active infection, would allow researchers to test the blood of people who were not confirmed cases of Covid-19 in communities where the virus spread. They would be designed to look for signs that people have mounted an immune response after being exposed to the virus.

https://www.statnews.com/2020/03/11/cdc-developing-serologic...

[bart_spoon]

> Are there countries who conduct serologic tests? PCR tests (widely used?) wouldn't catch people who got the infection, developed antibodies with no or mild symptoms, but didn't transmit the virus around at the moment test is taken.

Not that I know of. On the most recent "This Week in Virology" podcast, they mentioned that China has recently said they won't be doing serologic testing, which lead them to think that China has reason to believe the disease is far more widespread than their official numbers show. This may be in line with the idea that most infections are asymptomatic.

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Another source:

> "The current PCR test only tells you whether a person has the virus at this moment," Dr Meru Sheel, an epidemiologist and research fellow at the Australian National University said.

> "What it doesn't tell you is that a person may have had the infection, has recovered and is immune or not immune."

> Dr Sheel said a serological test would help understand at population level how many people have been exposed to the disease, have recovered and if there are populations that are not immune to the virus.

https://www.abc.net.au/news/2020-03-17/coronavirus-experts-c...