Your COVID-19 test came back negative – unfortunately, it might be wrong. Here’s what to do

COVID-19 testing sites across the country are administering nearly twice as many tests a day, compared to this summer, as case numbers climb and people hope to travel for the holidays. A negative test, however, actually can be misleading. (Shivani Majmudar/MEDILL)

Many of us have found a new normal amid the coronavirus pandemic: getting tested for COVID-19 early in the week and hoping for a negative result by the weekend so we can gather safely with a few friends.

But public health experts say that people are getting too comfortable with a negative test result, using it to justify pre-pandemic behavior. The consequences likely contributed to the current surge of COVID-19 cases and related deaths across the country.

“Right now, we’re in the middle of a wildfire that’s burning out of control,” said Dr. Eve Bloomgarden, an endocrinologist physician at Northwestern University. “If you’ve been exposed to the virus, you should quarantine regardless of what your test result says.”

The Centers for Disease Control and Prevention reports that the U.S. is averaging nearly 190,000 new COVID-19 cases and more than 2,000 deaths daily – shattering the virus’s first wave records.

Contentions that more testing simply resulted in more cases undermine the crisis. While testing in Illinois began to routinely top 70,000 per day in mid-September, daily new caseloads remained relatively low. Cases grew exponentially in the following weeks, surpassing 4,000 cases a day by mid-October and hitting more than 12,000 a day by mid-November, while testing only increased incrementally.

Public health experts warn this surge should not be taken lightly. The skyrocketing percentage positivity rates – hitting 13% in Chicago and as high as 29% in some parts of Illinois – compounded with rising hospitalizations and intensive care unit admissions reveal the sobering truth: the virus is still raging.

The incubation period for SARS-CoV-2, the virus that causes COVID-19, is anywhere between two and 14 days. In other words, it can take up to two weeks for your body to produce symptoms related to the infection, including fever, body ache, fatigue and shortness of breath. Symptoms appear on average four to five days after exposure.

“What’s particularly challenging with COVID-19, though, is that it affects people differently, including asymptomatically,” said Dr. Leo Nissola, an oncologist and medical advisor for COVID Act Now. He explained that a COVID-19 positive patient who does not experience any symptoms early on or at all can still transmit the virus, outlining a dangerous situation.

In fact, research suggests that some of the highest rates of transmission occurs 48-72 hours before the onset of symptoms, which then often force infectious people into quarantine.

For similar reasons, it’s also likely to receive a false negative test result just one or two days after exposure. The virus may not have replicated enough to be detected yet.

Experts advise that people should wait at least three days after a possible exposure to get a test. People should quarantine for 14 days regardless of the result though, if exposed to a known positive.

“This adds to the narrative of why consistently wearing face masks, washing hands and practicing social distancing, in addition to testing, is so important until a vaccine is ready,” Bloomgarden said.

COVID-19 transmission rates are so high in part because it takes time for the body to generate enough viral particles to be detected in a test and asymptomatic people can still be infectious. Because of this, experts advise against in-person gathering for the holidays. (Shivani Majmudar/ MEDILL)

Among COVID-19 tests, false negatives are generally more common than false positives. But false test results aren’t limited to the coronavirus – no medical test is perfect. The challenge unique to the pandemic is the inconsistent messaging about when to get tested and how to interpret test results, according to Bloomgarden.

“The delayed turnaround time for test results and the lack of clear instruction to quarantine at the time you get your test is really contributing to the spread of the virus,” she said. The co-founder of Impact4HC, a coalition of physicians and health professionals to advocate for the health needs of Illinois’ communities, also said combating misinformation, the infodemic, has created a “second fight.”

Dr. Andrew Trotter agreed, adding that messaging that suggests testing is harmful – or even vaccines — impacts the public’s willingness to take them. Trotter is an infectious diseases physician at the University of Illinois-Chicago. If not enough people choose to get tested, he said, it won’t be as effective.

Getting tested is easy, and does not have to be painful. Take a look at what your testing experience might look like:

 

Testing is an important aspect of overall efforts to contain the virus. In the last eight months, national testing capacity has grown exponentially. Several new COVID-19 test models have been developed and scaled to diagnose current infection or identify past infection. These range from traditional deep nasopharyngeal swabs, which some associate with discomfort, to saliva and blood tests.

Here’s a breakdown of the most common COVID-19 tests:

Molecular tests, such a polymerase chain reaction tests, are the “gold-standard” of COVID-19 tests that are administered. They test for an active COVID-19 infection by detecting the specific genetic material of the virus itself, making them the most accurate. Molecular testing mechanisms and their reliability have remained fairly consistent throughout the pandemic, although now patients can receive an oral swab, anterior nasal swab or a saliva test, in addition to the traditional deep nasal swab.

Although PCRs generally only take a few hours to run, the long turn-around times and national reagent supply shortages have been an ongoing challenge since March. From beginning to end, the process also requires complex lab infrastructure, including personnel and specific tools, according to Trotter.

“PCR tests are not very accessible to some people, especially in rural areas,” Trotter said, noting that even with mass testing, there are still some communities left without access.

In places without the required machinery at a nearby institution, swabs can be sent to large reference labs, like Quest Diagnostics. But this can delay test results for as long as seven days, which can be especially risky in the case of infectious, asymptomatic patients.

For quicker results, an antigen test is a common alternative. Antigen tests are also performed via a nasal or oral swab, but instead look for specific protein fragments on the surface of the virus.

They’re known as “rapid tests” because results are received usually within an hour, an asset during an ever-evolving pandemic. Antigen tests also require only a few supplies, making them easily portable.

“Antigen testing has increased the accessibility of testing, which is an important part of a public health response,” Trotter said. “You can reach a lot more people in the community because you can run the test in a parking lot.”

Antigen tests are highly specific to the viral protein for COVID-19, so a positive test result is likely true (although, the U.S. Food and Drug Administration released a letter last month noting that false positives can happen). As in every COVID-19 positive case, the exposed individual should isolate for at least ten days from the test result date and present without fever for at least 24 hours before seeing others, per CDC guidelines.

The bad news is that false negatives are more common under antigen tests, meaning that you might actually be infected with COVID-19 even if you received a negative result. False negative rates are reported as low as 2% and as high as 37%.

A negative antigen test result could warrant a confirmatory PCR test, especially for those who have been exposed to large groups of people, a known positive or have symptoms. The CDC recommends receiving a second test within two days and avoiding any risks for new exposures.

When patients get tested, Trotter emphasized it’s important for patients to be screened about their previous exposure so that providers can appropriately advise them on the safest course of action while they wait for test results and when the results come back.

Trotter said testing for common infections, like strep throat, similarly uses different types of testing in tandem. Usually, doctors first give patients a rapid test which gives results in minutes. Depending on the result, they will then perform the gold-standard, confirmatory test.

“What’s different about COVID-19, though, is that there are so many different ways of testing are being investigated and the information is changing so rapidly,” Trotter said.

If you get tested for COVID-19, follow these guidelines. Quarantine means staying at home, away from others. Isolation means staying at home, away from other people even in the same household. (Shivani Majmudar/MEDILL)

Both molecular and antigen tests diagnose current COVID-19 infections. Antibody tests instead identify previous contagion due to the virus, even if a person had no symptoms. Through a blood sample, this test detects whether or not a patient’s body has produced antibodies specific to COVID-19. Antibodies are memory-cells in the immune system that help fight infection and protect against that same infection the next time the body is exposed.

A positive antibody test does not mean that you are infectious with the coronavirus. Rather, it means that you were exposed to the virus in the past and your immune system fought off the infection. It can take up to three weeks after infection to produce antibodies, according to the CDC. Further research needs to be conducted to determine how long COVID-19 antibodies remain in the body and their long-term effectiveness.

The ultimate goal is to have a diverse range of accurate tests and an abundant supply to “fit all the different needs and preferences of people,” Trotter said. He highlighted the evolution of HIV testing, which now has enough versions for people to take the type of test that they’re most comfortable with.

With so many manufacturers focused on COVID-19 testing, new tests are being developed constantly to meet the overwhelming demand. USA Rapid Test created a rapid antibody test, which businesses can implement to quickly screen employees and patrons. Just over two weeks ago, the U.S. Food and Drug Administration issued an emergency use authorization for the Lucira COVID-19 All-In-One Test Kit, the first at-home diagnostic COVID-19 test.

As important as testing has been, health experts agree testing and isolation alone cannot match the current, unprecedented rates of community transmission, which are expected to rise even further after the holidays. A vaccine eventually will be the most effective tool against COVID-19.

“Testing is only a component of the strategy, with masking, quarantining and social distancing of course,” Trotter said. “But right now, until a vaccine, it’s the only strategy we have.”

Shivani Majmudar covers health, environment, and science at Medill. You can follow her on Twitter at @spmajmudarr.
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