Could saliva and rapid antigen tests be coronavirus game-changers in time for family gatherings this holiday – cleveland.com

CLEVELAND, Ohio Since the outset of the coronavirus pandemic, diagnostic tests that could quickly and accurately tell if someone is positive or negative have been something of a holy grail.

Having access to a rapid and reliable test could be a game-changer. It could alert people if theyve contracted the virus so they can take precautions to protect others. But it also could tell people if theyve tested negative, theoretically making it safer for families and friends to gather for birthdays or holidays like Thanksgiving and Christmas.

The U.S. Food and Drug Administration recently granted emergency approval to a pair of tests that offer such hope.

The SalivaDirect test, developed by the Yale School of Public Health, tests a persons saliva for the virus. BinaxNOW, an antigen test developed by Abbott Labs in Chicago, detects a specific viral protein and promises results in 15 minutes. BinaxNOW uses a nasal swab to obtain a sample.

Could either be the hope that so many are holding out for? Could it be possible to take a test on Thanksgiving morning and have your results before the family comes over for dinner?

Northeast Ohio medical experts say the latest tests offer promise but think its unlikely theyll have us back to normal in the next several months.

SalivaDirect tests do hasten the testing process, but they still require a saliva sample be sent to a laboratory for results, said Dr. Thomas File, the chair of infectious diseases at Summa Health and president of the Infectious Disease Society of America.

A lot of people are referring to it as a game-changer. Well, Im not sure its a game-changer, because it does require going to a lab and it requires a device to assess the results, File said.

BinaxNOW gives quick results, but still needs to be administered by a health care worker. And while Abbott Labs has said the test is accurate, rapid antigen tests are considered less reliable than the gold-standard polymerase chain reaction (PCR) tests.

Just last month, Ohio Gov. Mike DeWine was the focus of a media frenzy when he tested positive on a rapid antigen test before a scheduled meeting with President Donald Trump in Cleveland. He subsequently tested negative on two PCR tests.

Theres usually a trade-off between accuracy and quick results, said Dr. Daniel Rhoads, who specializes in pathology and laboratory medicine at Cleveland Clinic. He said rapid tests may be useful for screening 20-year-old students on a college campus, but theyre not used for someone who arrives at the hospital with COVID-19 symptoms.

It really depends what your goal is, and your tolerance for false positives and false negatives, he said.

The other drawback for rapid tests is availability. Abbott Labs has said it plans to produce 50 million BinaxNOW tests per month by the beginning of next month. But that only amounts to one-sixth of the U.S. population getting one test per month, Rhoads pointed out.

Rhoads said hes optimistic about the overall advances in testing, but were not to the point where anyone could go to a drug store and pick up a coronavirus test the same way theyd buy a rapid pregnancy test.

Were definitely not there yet, Rhoads said.

Doctors are optimistic but cautious

Though the U.S. has a long way to go to meet its testing needs, medical experts say the latest developments are promising.

The SalivaDirect test is much less invasive than the nasal swabs that are traditionally used to collect a sample of a respiratory virus. Patients could even collect their own samples, eliminating the need for face-to-face contact with health care workers. That could save time and preserve the personal protective equipment those health care workers need for those interactions.

The SalivaDirect test compared favorably to a nasal swab, Yale researchers found in a recent study. Health care workers used nasal swabs to confirm infections in 70 patients when they were admitted to a hospital. The researchers then took additional nasal swabs and saliva samples while those patients were hospitalized.

They found 81% of the saliva samples came back positive one to five days after the initial diagnosis, compared to 71% of nasal swabs. The saliva tests also detected more of the viruss genetic material.

These findings suggest that saliva specimens and nasopharyngeal swab specimens have at least similar sensitivity in the detection of [the coronavirus] during the course of hospitalization, the researchers concluded in the study.

The SalivaDirect test is faster because it cuts out the process of extracting the RNA of the virus from the sample, which medical experts say improves the accuracy of testing. Skipping that step could make a test less likely to detect some positive results where low amounts of the virus are present, Rhoads said.

Oftentimes, if you skip that extraction step, it works most of the time. But youre not going to detect those low positives," he said.

Nevertheless, both Rhoads and File see advantages in getting quicker results. It could take a full week for a person to get the results of a more accurate nasal swab test, and they could pass the virus to other during that time. The rapid tests are also more convenient, they said.

We have to be aware that with these more rapid tests, youre probably losing some accuracy," File said. "But if its really convenient and you get a really fast turnaround time, theres going to be a trade-off there thats going to be helpful.

However, both doctors said rapid testing should not be considered a replacement for other measures to limit the spread of the coronavirus. Its still important to wash your hands, wear a face mask and practice social distancing. And large gatherings, particularly those indoors, will continue to carry risk until the pandemic is controlled. File noted that states reported spikes in coronavirus cases after Memorial Day and the Fourth of July, so families should be cautious if theyre gathering for Thanksgiving or Christmas.

Everything we do to reduce transmission is going to be helpful in trying to control the virus, particularly at those holiday times," he said.

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Could saliva and rapid antigen tests be coronavirus game-changers in time for family gatherings this holiday - cleveland.com