Pandemic Raises Difficult Issues About Limits of Tests for COVID-19, Other Diseases
Existing COVID-19 test shortages are highlighting the critical role that testing plays in containing and mitigating diseases. Test results essentially provide a clue at a particular point in time. Even when a test result is precise and meaningful, however, it will not be useful unless appropriate action is taken. False positives may commonly occur for such assays as hepatitis C antibody tests and mammograms that search for medical problems in healthy people without symptoms. Deborah Korenstein, who heads the general medicine division at Memorial Sloan Kettering Cancer Center in New York City, observes: "High-tech diagnostic testing has led to this mirage of certainty. Back in the day before there were MRIs and whatnot, I think doctors were more cognizant of how often they were uncertain." In the case of COVID-19 tests, polymerase chain reaction tests are estimated to have a false negative rate of up to 30 percent, by some estimates. This rate can vary depending on factors like who collects the sample, the area of the body it is collected from, and the progression of the potential infection. To ascertain if a person was previously infected by the coronavirus, health care professionals administer an antibody test. A negative antibody test could mean the patient was never infected, is infected but has yet to build up antibodies, or the antibodies are already diminished. A positive test may also erroneously detect antibodies to viruses that appear similar, and even if the test shows a correct positive result for COVID-19, it remains unclear if the patient is safe from reinfection. Such variability prompted the Centers for Disease Control and Prevention and health systems to clear patients based on time rather than a negative test.
3 States Reporting Low to Moderate Influenza Activity
Becker's Hospital Review
The Centers for Disease Control and Prevention's FluView report for the week of November 21 indicates that seasonal influenza activity in the United States rose slightly from the previous week but is still low for this time of year. According to the report, influenza activity nationwide represented 1.6 percent of outpatient visits for the week ending November 21, up somewhat from the previous week but below the national baseline of 2.6 percent. No states reported high or very high influenza activity during that period, while Rhode Island reported moderate activity and New Mexico and New Jersey reported low activity. The percentage of respiratory specimens testing positive for influenza at clinical laboratories remained the same as the previous week, at 0.2 percent. The data show that 49.9 percent of positive influenza specimens collected since September 27 were identified as Influenza A, while 50.1 percent were Influenza B. Nationwide, the mortality rate for influenza and pneumonia is 11.3%, above the epidemic threshold of 6.3 percent. These deaths are attributed to influenza, pneumonia, or COVID-19.
NASA Develops the 'E-Nose,' a Handheld Breath Analyzer That Can Measure Multiple Biomarkers Used in Medical Laboratory Tests
Researchers associated with the National Aeronautics and Space Administration (NASA) are working to develop diagnostic tests based on human breath. The researchers recently introduced a prototype device, the E-Nose Breath Analyzer, which is designed to perform diagnostic tests using breath specimens. The hand-held device, which is still under development, "will have the capability of analyzing compounds found within a person's breath to diagnose a battery of illnesses and abnormalities including respiratory illnesses, infectious diseases, and cardiovascular conditions," according to an Air Force news release. David Loftus, MD, PhD, medical officer and principal investigator of the Space Biosciences Research Branch at NASA's Ames Research Center in Silicon Valley, Calif., demonstrated the first working prototype of the device during a presentation at the David Grant USAF Medical Center on Travis Air Force Base. He explained, "The technology is designed to make rapid measurements—in less than 5 minutes, at the point of care—in a way that is completely non-invasive. When fully realized, the NASA E-Nose will open a new realm of medical care to both the warfighter and potential space travelers." Research shows the device can detect 16 different chemicals in seconds at room temperature, using a variety of chemical sensors combined with humidity, temperature, and pressure.