A growing list of people who were in close contact with President Donald Trump have tested negative for COVID-19, including some of his children and Democratic presidential nominee Joe Biden, but experts warn it doesn't mean they are off the hook: A single negative test doesn't mean a person doesn’t have the virus.
Diagnostic tests look for traces of the coronavirus in a person's body at that exact moment and it “takes a number of days for the virus to replicate enough to be detected,” according to Dr. Alan Wells, medical director of clinical laboratories at the University of Pittsburgh Medical Center, NBC News reports.
Because of this, the Centers for Disease Control and Prevention advises anyone who may have been exposed to quarantine for 14 days, which is believed to be the extent of the incubation period.
The type of test being given is also a factor. Molecular or PCR tests that are sent to a lab for analysis are more reliable than rapid tests, which produce results in about 15 minutes, but are less sensitive. Trump and close White House contacts have reportedly been tested with a rapid test called the Abbott ID NOW.
In May, the FDA put out an alert warning doctors that people testing negative with the Abbott ID NOW test may need a second lab-based test. It's unclear whether Trump or his close contacts have received a second test.