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Fact check: A swab test is highly unlikely to misdiagnose flu or common cold as COVID-19

Social media users have been sharing a post saying any cold or common flu can be misdiagnosed as COVID-19. This is misleading.

Reuters Fact Check. REUTERS

One Facebook user says their relative was told by a doctor in New York that “any cold or flu can show up positive on a COVID test.” The post does not mention the type of test (here) .

There are two main types of tests — a swab or a polymerase chain reaction (PCR) test and an antibody test (here) (here) .

A swab test is used to diagnose whether a person has COVID-19 currently. Antibody tests to detect if someone has been infected by the novel coronavirus are being used by scientists to learn more about how many people have had the infection. They are not widely available in Britain (here) .

Scientists say the swab tests are specially designed to detect SARS-CoV-2, the virus responsible for COVID-19.

These tests, which work by detecting the genetic material of the SARS-CoV-2 virus, (here) are “very specific, said Dr Rob Shorten, Chair of Microbiology Committee, Association for Clinical Biochemistry & Laboratory Medicine.

“The specific nature of these sequences means that someone with flu or a common cold virus is highly unlikely to test positive for COVID-19,” he told Reuters.

“The Covid PCR test has pretty good specificity and sensitivity so it’s not that much of a problem. The test is more likely to throw a false negative than it is a false positive,” Dr Joshua Moon, research fellow in the Science Policy Research Unit at the University of Sussex Business School, said.

However, the antibody tests, which determine if a person has had virus, can sometimes pick up other seasonal coronaviruses.

“People are seeing some cross-reactivity in antibody tests,” said Dr Mike Skinner, Reader in Virology in the Department of Infectious Disease, Imperial College London. He said only about 20% of colds are caused by the seasonal coronaviruses, and the rest by rhinoviruses.

The U.S. Centers for Disease Control and Prevention advises that antibody test results should not be used to diagnose someone with an active infection (here) .

VERDICT

Partly false: The claim that tests can misdiagnose a common cold as COVID-19 are misleading. Swab tests used to diagnose COVID-19 are highly specific, experts say. Antibody tests, however, can establish if someone has antibodies from other coronaviruses, but they are not being used to diagnose COVID-19.

This article was produced by the Reuters Fact Check team. Read more about our work to fact-check social media posts here .

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