According to the 9th edition of the Novel Diagnostic and Treatment Program for Novel Coronavirus Pneumonia published, a nucleic acid test CT (cycle count threshold) value ≥35 is considered normal. The higher concentration of viral nucleic acid indicates that fewer cycles are needed for amplification, and the smaller the CT value; on the contrary, the lower concentration of viral nucleic acid, the larger the CT value. When the nucleic acid CT value is ≥35, the virus can no longer be cultured and no longer has a risk of transmission. Our latest guidelines for nucleic acid testing changed the original CT40 to CT35, lowering the criteria for defining a positive nucleic acid. Therefore, a CT ≥35 is now considered normal. The new coronavirus is highly contagious, in order to reduce the spread of the epidemic, travelers in high-risk areas are advised to cooperate with the relevant departments to conduct nucleic acid testing. Tip: “New coronavirus pneumonia” and “new coronavirus pneumonia” mentioned in this article were renamed to “new coronavirus infection” on December 26, 2022, as announced by the National Health Commission.