Antibody tests that were supposed to help provide guidelines on how and when America can safely reopen have proven to be unreliable. A wide variety of blood tests, which allegedly measure whether a person has been infected with the coronavirus, were approved by the Food and Drug Administration (FDA) and widely marketed to hospitals, doctors, and consumers.
But experts say they are far from perfect and often give skewed results called "false positives" that are misleading, according to USA Today.
"We need to stop pretending the tests are perfect," said Colin West, a Mayo Clinic internal medicine doctor and professor who has tracked the accuracy of COVID-19 tests. He said a person who gets tested should not "stop wearing a mask or stop washing their hands. Or stop physically distancing."
The World Health Organization (WHO) warned against issuing "immunity passports" to people who believe they are safe based on positive antibody tests. Last week, WHO issued a statement saying:
"At this point of the pandemic, there is not enough evidence about the effectiveness of antibody-mediated immunity to guarantee the accuracy of an 'immunity passport' or 'risk-free certificate.' People who assume that they are immune to a secondary infection because they have received a positive test result may ignore public health advice."
WHO warned that ignoring current health guidelines could "increase the risks of continued transmission."
Experts say that the FDA likely rushed the approval for antibody testing because the nation's vast network of hospital and private commercial labs did not get the green light for COVID-19 test kits from the federal agency until late February.
"The FDA was behind the eight ball when it came to early diagnosis," Peter Pitts, a former FDA associate commissioner, told USA Today. "Not surprisingly, they didn't want to get burned twice."
Aside from the questionable accuracy of the tests, experts say there has been mixed evidence on whether or not having the virus actually gives you immunity in the first place. While theoretically, antibodies protect people from a second infection, there's no guarantee how long protection might last or whether it's completely effective. It will take time to collect enough information from studies to answer these questions, according to USA Today.
"We are dealing with a pandemic that demands rapid action," West told USA Today. "But developing a robust evidence base with rigorous methodology is not a rapid process."