Even under ideal circumstances, the best products will occasionally fail, Dr. Jha said.
“There is not something that is 100 percent perfect,” he said. “That’s why you do confirmatory tests.”
Alabama swiftly began its investigation into Saban’s positive result. There were medical reasons to try to confirm the result, but urgent football ones, too.
Less than a week before Saban said he had tested positive, the SEC’s chancellors and presidents had approved an update to the league’s medical protocols. Under the new policy, an asymptomatic person like Saban who tested positive for the virus could take another P.C.R. test within 24 hours. If that test yielded a negative result, the person could take two more P.C.R. tests, each separated by 24 hours. If all three results were negative, the player, coach or staff member could return to athletics.
Confused by the terms about coronavirus testing? Let us help:
- Antibody: A protein produced by the immune system that can recognize and attach precisely to specific kinds of viruses, bacteria, or other invaders.
- Antibody test/serology test: A test that detects antibodies specific to the coronavirus. Antibodies begin to appear in the blood about a week after the coronavirus has infected the body. Because antibodies take so long to develop, an antibody test can’t reliably diagnose an ongoing infection. But it can identify people who have been exposed to the coronavirus in the past.
- Antigen test: This test detects bits of coronavirus proteins called antigens. Antigen tests are fast, taking as little as five minutes, but are less accurate than tests that detect genetic material from the virus.
- Coronavirus: Any virus that belongs to the Orthocoronavirinae family of viruses. The coronavirus that causes Covid-19 is known as SARS-CoV-2.
- Covid-19: The disease caused by the new coronavirus. The name is short for coronavirus disease 2019.
- Isolation and quarantine: Isolation is the separation of people who know they are sick with a contagious disease from those who are not sick. Quarantine refers to restricting the movement of people who have been exposed to a virus.
- Nasopharyngeal swab: A long, flexible stick, tipped with a soft swab, that is inserted deep into the nose to get samples from the space where the nasal cavity meets the throat. Samples for coronavirus tests can also be collected with swabs that do not go as deep into the nose — sometimes called nasal swabs — or oral or throat swabs.
- Polymerase Chain Reaction (PCR): Scientists use PCR to make millions of copies of genetic material in a sample. Tests that use PCR enable researchers to detect the coronavirus even when it is scarce.
- Viral load: The amount of virus in a person’s body. In people infected by the coronavirus, the viral load may peak before they start to show symptoms, if symptoms appear at all.
It is unusual to administer a follow-up screening after someone tests positive by P.C.R., and the Centers for Disease Control and Prevention recommend that such a result send an asymptomatic person into isolation for 10 days.
But in the weeks before Saban’s test, the conference had an experience with a false positive involving a soccer player at Texas A&M, Sports Illustrated reported. And the league’s medical experts had also begun to worry about the potential public health effects of an unchecked false positive: a person’s being dropped from routine testing and perhaps acquiring a sense of invincibility that they could no longer contract the virus — potential fodder for an outbreak, should that person be exposed.
“The repercussions for that false positive aren’t just for that athlete,” said Dr. Catherine O’Neal, an infectious disease specialist at Louisiana State University and a member of the SEC’s medical task force. “It puts the entire team at risk.”
Still, Dr. O’Neal said she had worried about endorsing a protocol that “debunks a test result.”
“There’s so much attention around the validity of these tests, and for us who work in health care, just convincing patients to trust us and trust getting tested has become a struggle,” she said. “We don’t want to give the perception that we don’t believe these tests.”