Coronavirus antibody testing is supposed to tell who’s been exposed to the virus, but questions have risen about how accurate they are and how much protection those antibodies provide. Meanwhile, the World Health Organization is warning officials that they should not use these tests to provide so-called “immunity passports.”

Finding out who has been exposed to the coronavirus has been identified as a key to reopening the country. But there are problems.

The WHO said there’s no guarantee of immunity after infection but here in the U.S., medical experts overwhelmingly agree that the antibodies that remain give some level of protection.

“So the tests that we have now on the market … Don’t tell you individually whether you have the neutralizing antibodies, whether you have the antibodies that can prevent you from getting an infection again,” CBS News medical contributor Dr. David Agus said.

Of the more than 160 antibody tests flooding the market, the FDA has only given emergency use authorization to eight.

Bioengineer Patrick Hsu from U.C. Berkeley and colleagues set out to see how many are accurate. Results so far are mixed.

“There are definitely some that are better than others,” Hsu explained. “We see out of the 10 we tested … I think that’s three that after two weeks were 90% positive.”

Along with new symptoms, there are new clinical trials.

The Feinstein Institutes for Medical Research at Northwell Health is quietly testing the acid reflux medication Pepcid, also known as famotidine, to see if it blocks the virus from replicating.

“We don’t know if taking famotidine causes more harm than good,” Dr. Kevin Tracey, president of the Feinstein Institutes, told CBS News. “We will be studying hundreds of patients who are hospitalized, receiving intravenous famotidine.

Researchers are currently studying whether acid reflux medication helps treat the coronavirus. Right now, there’s no evidence that it does. Doctors stress the potential dangers in misusing drugs — prescription or over the counter. Bottom line: always consult your physician.