Nucleic acid testing is not recommended just after vaccination and is generally recommended at least the second day after vaccination. This is because nucleic acid testing is a test that clarifies the presence of viral infection by detecting the nucleic acid fragments in the virus. There are two common reasons why the test may be positive on the same day: 1. The nucleic acid fragment is still present: The inactivated vaccine is made from the new coronavirus through culture and inactivation, and although the virus has lost its vitality and cannot be infectious and pathogenic to the organism, the nucleic acid fragment of the new coronavirus is still present in it. The sensitivity of nucleic acid detection is high, so positive nucleic acid detection may occur just after vaccination. 2. Vaccine contamination: During the vaccination process, when the vaccine is extracted and the syringe is exhausted, the vaccine may contaminate the vaccination site, the vaccination personnel and the vaccinator, which may lead to the presence of nucleic acid sequence of the new crown virus in the nasal cavity or throat of the vaccinator and affect the nucleic acid detection results. Therefore, it is recommended that nucleic acid testing be performed at least the next day after vaccination. If the vaccinator urgently needs nucleic acid testing, it is recommended that the institution concerned be consulted in a timely manner to clarify the fastest time for testing and the results will be a little more accurate.