China is requiring some foreign travelers entering the country to get invasive anal swab coronavirus tests, and many are concerned. 

What is an anal swab, and is it better at detecting the virus than other tests?

Some scientists believe traces of COVID-19 can live longer in the rectum than the respiratory system, so an anal swab is believed to be more accurate.

The digestive tract also can have a larger concentration of virus so patients who are asymptomatic or have lower levels of virus might get more accurate results by anal swabs.

The anal swab test is self-administered by inserting a saline-soaked cotton swab about 2 inches into the anus, then swirling it around the rectum a few times.

Anal swabs and stool tests seem to be better at catching the virus in children than nasal tests. Research shows children hold more virus in their stool than adults.

Others say that that nasal swab tests are better because the virus lives primarily in the respiratory tract.

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