“[Pre-flight testing] probably did prevent some people with active infection from entering [the United States],” said Karen L. Edwards, PhD, a professor in the public health program and chair of the department of epidemiology and biostatistics at University of California, Irvine. “However, it will never be 100 percent effective, just given the variation we see in terms of susceptibility, infectivity, as well as characteristics of the virus, such as length of the incubation period,” she added.
Most countries stopped requiring COVID tests for air travel. Why hasn’t the US?
Healthline, May 31, 2022
May 31, 2022