False negative covid test results12/22/2023 ![]() ![]() First, continued strict adherence to physical distancing, hand-washing, surface disinfection, and other preventive measures is required regardless of risk level, symptoms, or COVID-19 test result. To the extent that asymptomatic spread may contribute to disease transmission and serious illness, these policies could place colleagues and patients at ongoing risk.Īt least four recommendations seem prudent given these concerns ( Table 6 Furthermore, restrictions on untested or test-negative asymptomatic health care workers with community exposures are limited or absent. At present, the Centers for Disease Control and Prevention guidelines for asymptomatic health care workers with negative COVID-19 testing are based on both the nature of clinical exposure to COVID-19 patients and personal symptoms, so that negative testing in an asymptomatic health care worker could lead to an immediate return to work for many engaged in routine clinical care. Regardless of the exact total, every one of these health care workers could spread disease despite the seeming reassurance of a negative COVID-19 test. If the sensitivity of the test were only 70%, as cited in early reports, 5 the number of false-negative results would triple to well over 100,000. If the COVID-19 infection rate among the more than 4 million doctors, nurses, and other clinicians providing direct patient care in the United States were even 10% (far below most national prevalence predictions), more than 40,000 false-negative results would be expected if every clinician were to receive a test. Even if only 1% of the population were tested, 20,000 false-negative results would be expected. With a population of 40 million people, 2 million false-negative results would be expected with comprehensive testing. ![]() Similarly, it has been estimated that the COVID-19 rate in California may exceed 50% by mid-May 2020. Even with less widespread testing or targeted testing among random samples, the number of false-negative tests could be massive. If the entire population were tested, of the anticipated 5.2 million infected individuals, 520,000 people would be falsely classified as free of infection. The president of the region of Madrid has predicted that 80% of Madrid’s 6.5 million residents will become infected by COVID-19. To illustrate the potential magnitude of this problem in the general population, consider the following examples from Spain and the United States, assuming a test with 90% sensitivity. In the case of clinicians, they may be sent to the frontlines of care and inadvertently transmit the virus to patients and colleagues, further straining the already precarious ability of the health care system to respond to the pandemic. ![]() Individuals with these results may relax physical distancing and other personal measures designed to reduce the transmission of the virus to others. Why is this relevant to stopping the spread of COVID-19? False-negative results are consequential. 5 Even with sensitivity values as high as 90%, the magnitude of risk from false-negative test results will be substantial as testing becomes more widespread and the prevalence of COVID-19 infection rises. 4 The diagnostic sensitivity of reverse transcriptase–polymerase chain reaction (RT-PCR) testing for other viruses is highly variable, but early data from China suggested relatively poor sensitivity of initial RT-PCR tests. Sensitivity is particularly important in understanding the risk of false-negative testing. Fundamental characteristics of clinical diagnostic tests for COVID-19 infection including sensitivity, specificity, and corresponding likelihood ratios are largely unknown. The magnitude of this concern is difficult to determine because test performance characteristics (and the validity of the studies generating them) have not been reported clearly or consistently to date. Specifically, anticipation of a less-visible second wave of infection from individuals with false-negative test results is needed. For negative test results in particular, failure to do so has direct implications for the safety of the public and health care workers and for the success of efforts to curb the pandemic. ![]() 3 As tests become more available, observing principles of evidence-based clinical reasoning concerning the meaning of diagnostic test results is essential. 1, 2 Efforts to develop and implement testing protocols are underway, and expanded testing for COVID-19 is a necessary immediate step toward understanding and resolving this crisis. As health care systems around the world attempt to cope with the coronavirus disease 2019 (COVID-19) “tsunami,” concerns about ongoing spread of disease from individuals who are infected without symptoms have been raised. ![]()
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