Experts find flaws in China’s tests for travellers - China's unusual testing policy has left health experts baffled

An unusual new testing policy, announced by China at the end of October, has health experts baffled

Katherine J. Wu   |   TT  |  New York   |   15.11.20  :  New York: As cases of the coronavirus continue to climb worldwide, many countries are doubling down on testing policies that can grant or bar entry to travellers attempting to move across international borders.

But an unusual new testing policy, announced by China at the end of October, has health experts baffled. It requires inbound travellers to present negative results from an antibody test — which can neither reliably rule out infections nor prove that a person is not transmitting the virus to others.

“I don’t understand why they would be doing this,” said Dr Krutika Kuppalli, an infectious disease physician at the Medical University of South Carolina. “It seems like this is their method of security theatre.”

The strange guidelines, experts said, seemed to reflect an outdated understanding of the ways in which the virus and the immune system interact. In the spring, several companies attempted to market antibody tests as potential diagnostics of active infection.

Some (but not all) later tempered or walked back these advertisements as researchers gathered more information about the timing of the antibody response to the virus, which does not kick into gear until levels of the pathogen are waning.

“I thought we were past this stage,” said Elitza Theel, a clinical microbiologist and expert in antibody testing at Mayo Clinic in Rochester, Minnesota. Guidelines from the Centers for Disease Control and Prevention describe antibody positives as a poor proxy for the presence of active virus in the body.

Previous iterations of China’s policies stipulated that travellers would need to test negative only by a “nucleic acid test”, a tool that hunts for the coronavirus’s genetic material. Most available tests that meet this requirement rely on a laboratory technique called polymerase chain reaction, or PCR, which can home in on the virus even when it is present at very low levels in the body.

New York Times News Service