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COVID-19: Negative test result gives a false sense of security

COVID-19: Negative test result gives a false sense of security



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Negative corona tests do not offer security

The current tests for the detection of an acute infection with the new corona virus SARS-CoV-2 can give a false sense of security if the test result is negative and thus indirectly have a significant impact on the containment of the pandemic, warn researchers at the Mayo Clinic (USA). For example, the health authorities have to expect a "less visible second wave of infection from people with false-negative test results," warns the expert Dr. Priya Sampathkumar from the Mayo Clinic.

Excessive reliance on COVID-19 tests to make decisions in clinical and public health care harbors some risks, according to the researchers. Above all, the so-called RT-PCR tests (reverse transcriptase polymerase chain reaction) can lead to a false sense of security, which may negatively influence the weighing of measures and the assessment of the infection process, the researchers report in the specialist magazine "Mayo Clinic Proceedings".

Positive tests most useful?

The sensitivity of the RT-PCR test (reverse transcriptase polymerase chain reaction) and the general performance characteristics of the test are not clearly and uniformly described in the medical literature, according to the criticism in the article. Therefore, "RT-PCR tests are most useful when they are positive," emphasizes Dr. Sampathkumar. But they are less useful to rule out COVID-19. A negative test often does not mean that the person does not have the disease.

Test with a residual uncertainty

Because even with a test sensitivity of up to 90 percent, the extent of the risk of incorrect test results is considerable and with an increasing number of people tested, the number of incorrect test results will increase accordingly.

Using the example of California, the expert calculates that with an assumed infection rate of 50 percent of the population in 40 million people, 20 million would be infected. If ten percent of them wrongly failed the test, it would be two million people who were undetected. Even with 99 percent test accuracy, 20,000 false negative results remained.

Impending health effects

The paper also outlines the potential impact on health workers in the United States. “If the COVID-19 infection rate among the more than four million people providing direct patient care in the United States were ten percent - well below most predictions - more than 40,000 false negative results would be expected if all were tested Warn the researchers.

Risk of retransmission

This poses a risk to the health care system in this critical time, because in the United States, "the CDC (Centers for Disease Control and Prevention) guidelines for asymptomatic health care workers with negative test results cause them to immediately return to routine clinical care return, which creates the risk of spreading diseases, ”says study author Dr. Colin West.

“For people with a really low risk, negative test results can be comforting enough,” says Dr. West. But for people at higher risk, even those without symptoms, "the risk of false negative test results requires additional measures to protect against the spread of the disease, such as increased self-isolation."

Various criteria should be considered

At the Mayo Clink, the RT-PCR test is only "one of many factors that we take into account when deciding whether the patient meets the criteria for COVID-19," emphasizes Dr. If the test is negative, but the results of the chest X-ray or CT scan are abnormal or there has been close contact with a diseased person, “the recommendation is to continue caring for the patient as if he had COVID-19. "

Minimize risk from incorrect test results

In order to avoid risks from false negative test results, four basic points are made in the Mayo Clinic contribution:

  • Furthermore, strict adherence to physical distancing, hand washing, surface disinfection and other preventive measures, regardless of risk level, symptoms or COVID-19 test results.
  • Developing highly sensitive tests or test combinations to minimize the risk of false negative results. Improved RT-PCR tests and tests for antibodies are required.
  • The risk of disease must be carefully assessed before testing and negative test results should be assessed with caution, especially in people from high-risk groups and in areas where widespread COVID-19 infections have been confirmed.
  • Risk-stratified protocols are required for dealing with negative COVID-19 test results (recording the risk of disease despite a negative test), which must evolve as more statistics become available.

In addition, the recommendations for dealing with asymptomatic patients and for exposed personnel in the healthcare system need to be further refined, summarizes Dr. (fp)

Author and source information

This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.

Dipl. Geogr. Fabian Peters

Swell:

  • Colin P. West, Victor M. Montori, Priya Sampathkumar: COVID-19 Testing: The Threat of False-Negative Results; in: Mayo Clinic Proceedings (published April 7th, 2020), mayoclinicproceedings.org
  • Mayo Clinic: False-negative COVID-19 test results may lead to false sense of security (published April 9th, 2020), mayoclinic.org


Video: Can a person test negative and later test positive for COVID-19? (August 2022).