Covid-19 test kit. One can (for)see production and rise of thousands of home-made "lab technicians" and "pathologists".
Even if the tests are 99% accurate, if you get a positive test then you probably have not been exposed. You would be much more likely to be among those never infected and get a false positive than be among those previous infected and get a true positive
So far there have been some 900 confirmed cases.
If we are generous, then from 5million adults in Hong Kong, say 5000 have been infected.
If all 5 million adults were tested, then out of the 4,995,000 who are not infected, 1% would give false positives. That makes it 49,950 would be given false positives.
Of the 5000 previously infected, 99% would get positives. That makes it 4950 would show the antibodies.
So only about 9% of positive antibody tests would be for people who actually had been previously exposed.
With infection rates set out above, for a positive test to have a 50/50 chance of correctly determining that a person was actually infected then you need the test to be 99.9% accurate.
In today's SCMP...
I'm assuming they did not use these DIY @ Home kits.
https://www.scmp.com/news/china/scie...uestions-aboutA team from Fudan University analysed blood samples from 175 patients discharged from the Shanghai Public Health Clinical Centre and found that nearly a third had unexpectedly low levels of antibodies.
In some cases, antibodies could not be detected at all.
“Whether these patients were at high risk of rebound or reinfection should be explored in further studies,” the team wrote in preliminary research released on Monday on Medrxiv.org, an online platform for preprint papers.
Although the study was preliminary and not peer-reviewed, it was the world’s first systematic examination of antibody levels in patients who had recovered from Covid-19, the disease caused by the coronavirus, the researchers said.