At present, nucleic acid generally refers to the new crown nucleic acid. Before performing the new crown nucleic acid test, fasting is usually not required, and it is possible to do it after a meal, but if the oropharyngeal swab is the main measurement method, it is not recommended to do the nucleic acid immediately. Whether or not to eat before the nucleic acid test is not directly related to the level of the virus, but if the test method is based on oropharyngeal swabs, extracting secretions from the pharynx, which may irritate the larynx during operation, nausea, vomiting, and other symptoms are generally not recommended to do the nucleic acid test immediately after a meal, in order to avoid causing discomfort to the test taker. Two hours before the new crown nucleic acid test, it is recommended to reduce eating or do not eat, do not smoke, drink alcohol, etc., so as not to cause nausea, vomiting and other discomforts, in addition, in the nucleic acid test, you should wear a mask, and to maintain the distance between people.