There is some variation in when the 48 hours of nucleic acid testing begins to count, depending on local policy requirements. In some places, the sampling time is projected backward within 48 hours, and in most places, the report time shown on the lab slip is projected backward within 48 hours. With the improvement of epidemic prevention, many places now require mobile workers to provide proof of nucleic acid testing within 48 hours, and usually also require 14 days of health monitoring in advance, with their health code and trip code, in order to travel normally. Usually the nucleic acid test results are available a few hours after sampling, or you can consult the relevant testing agency before sampling the report issuance time and arrange your trip in advance. China’s “Novel Coronavirus Pneumonia Treatment Protocol (Trial Version 7)” states that nucleic acid testing is the gold standard for confirming the diagnosis of novel coronavirus pneumonia, and accurate nucleic acid test results play an important role in the diagnosis of viral infection and outbreak prevention and control, so many places will require travel with nucleic acid results within 48 hours. Because of the presence of asymptomatic infected persons or patients with mild novel coronavirus pneumonia, failure to detect and control these patients in a timely manner can accelerate the spread of the virus and affect the restoration of normal social order. Therefore, it is more important for travelers to undergo nucleic acid testing, which requires attention and active cooperation.