Rapid, sensitive diagnosis of COVID-19 is essential for early treatment, contact tracing and reducing viral spread. However, some people infected with SARS-CoV-2 receive false-negative test results, which might put their and others' health at risk. Now, researchers reporting in ACS' Nano Letters have developed ultra-absorptive nanofiber swabs that could reduce the number of false-negative tests by improving sample collection and test sensitivity.