Nucleic acid can be tested as soon as possible after 72 hours, and you should also pay attention to the expiration date of your nucleic acid test before traveling. Due to the current recurring domestic outbreaks, some areas still require a 48-hour or 72-hour nucleic acid test, so if the nucleic acid test has expired by the time you arrive at your destination, you will need to take another nucleic acid test. Free nucleic acid testing is generally available at airports, highway exits, stations and other transportation venues, and waiting for the results is sufficient. Meanwhile, before traveling, you need to pay attention to the expiration date of your nucleic acid test, which is usually counted from the time of sampling, not the time of reporting, which needs special attention. It is better to take a nucleic acid test before traveling to avoid delaying your trip due to the expiration date of the nucleic acid test.