Why a False Negative Test Result Might Appear for the Coronavirus

As the number of coronavirus, specifically COVID-19, cases continue to spread, so does the panic worldwideWhile many are worried about getting infected, there are others that are worried about something entirely different; people being infected and their results coming back with a false negative result 

To educate those at BG about the coronavirus, Fan Xia, Sr. Laboratory Director of Clinical Genomics, gave an update on: 

  • What the coronavirus is 
  • What type of test is currently being used to detect it 
  • Why tests are coming back false 
  • How to take preventative measures to remain healthy  

What is the Coronavirus? 

According to the CDCthe coronavirus is part of a family of viruses that can be common in both people and animals. The name of the current virus is called “SARS-CoV-2, or also known as “coronavirus disease 2019” (COVID-19).  

The symptoms for the coronavirus and the flu are extremely similar, but some of the more common symptoms of the coronavirus are fever, dry cough, and shortness of breath. Typically, the seasonal flu affects 5 – 15 percent of the population, which results in 290,000 – 650,000 deaths per year.  

In contrast, according to CNN, the coronavirus has infected more than 113,000 people and has resulted in more than 4,000 deaths. According to Wiki Media, the coronavirus is spreading 2 – 3x faster than the seasonal flu, and the mortality rate is 7 – 30x higher. The main reason for the rapid increase and higher death rate ithe lack of a vaccine or validated drug to treat this type of disease.  

The primary question we are all wondering is: How do we combat a disease that spreads faster than the flu, without having a vaccine? The answer lies within the nucleic acid testing method adopted by the CDC since February. 

Coronavirus Testing Kit and False Negative Results 

Once the disease was recognized in China, the CDC acted very quickly and started testing the genome of the virus to find a solution. By early February, the CDC chose nucleic acid testing as the diagnostic gold standard for detection 

Through this testing method, the CDC’s official testing kit included three sample types. Even with three sample typeshospitals were still receiving false negative or inconclusive tests. Here are two main reasons they would see these results: 

  • User Error: On February 12, the CDC admitted that a patient’s sample was mislabeled which led to the patient being released with a positive coronavirus statusAccording to College of American Pathologists (CAP), pre-analytic and user errors contribute to more than 85 percent of false test results. Even after this human error, the CDC was still receiving inconclusive results, so they had to recall the reagent that they were using for the tests. If tests are not built out in a robust way and handled properly, there will be a lot of false negatives and pre-analytical errors. 
     
  • Sample Type and Test Sensitivity: In order to get accurate test results, labs must test all three probes and sample types (oral swabs, anal swabs and blood)Results showed that when you only tested one sample type, the test sensitivity was 20 – 50 percentAfter combining two samples, the test sensitivity was 50 – 70 percent 

While the fear of a false negative test happening lingers, it’s still important to note that recommendation of 14-day self-quarantine will minimize the risk of spreading. It’s imperative that anyone showing symptoms gets tested immediately 

Protecting Yourself from the Coronavirus 

While many people are feeling extra vulnerable with the disease spreading, the spread of the coronavirus can be limited through simple and intentional acts. Here are some basic tips to keep the home and workplace safe:  

  • Practice good hygiene by not shaking hands 
  • Wash hands regularly 
  • Avoid touching your face 
  • Cover sneezes and coughs 
  • Disinfect open areas 
  • Limit the amount of time spent in meetings and travel 
  • Instead of inperson meetings, see if virtual meetings are possible 
  • If feeling sick, stay home 

For more best practices on staying healthy and corona free, read the CDC’s list of preventative tips.  

Summary 

The coronavirus has rapidly become a worldwide pandemicCurrently there are over 113,000 people infected and around 4,000 deaths related to this disease. While the symptoms are very similar to the common flu, the main difference is the lack of a vaccine for the coronavirus and it spreads 2 – 3x faster than the flu 

To combat the disease, the CDC released a test kit in February which resulted in some of the results coming back as false negative or inconclusive. Some of the reasons for false negative tests include user error, not running multiple sample types, and the need for a stronger sensitivity 

It is crucial to be aware of all signs for the coronavirus and take precautionary measures at home and work. For the latest updates, please visit the CDC’s website 

 

Sources: 

Fan Xia, Sr. Laboratory Director at Baylor Geneticshttps://test-dev.baylorgenetics.com/people/fan-xia/ 

Center for Disease Control and Prevention: https://www.cdc.gov/coronavirus/2019-ncov/index.html 

CNN: https://www.cnn.com/2020/03/10/health/coronavirus-q-and-a-tuesday-march-10/index.html 

Wiki Media: https://commons.wikimedia.org/w/index.php?curid=86472036 

U.S. News: https://www.usnews.com/news/health-news/articles/2020-02-11/nearly-200-evacuees-to-leave-coronavirus-quarantine-in-us 

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