The resumption of positivity after omicron conversion is related to the virus still existing in the body, poor immunity, failure to form effective antibodies, and so on. 1. The virus still exists in the body, for the infected person to release from quarantine or discharge criteria for two consecutive negative nucleic acid test, and the negative standard is the CT value is less than 35, that is, zoomed in up to 35 times did not find a new coronavirus, but does not mean that there is no existence at all. Residual omicron viruses, can still continue to reproduce. 2. Poor immunity, after the infection is cured, generally the residual virus can be killed by autoimmunity. However, some people have poor immunity and are unable to fight the virus through their own immunity. 3. Failure to form effective antibodies. Usually, antibodies against the new coronavirus can be formed after cure, and people who have a relapse of the infection may be infected twice due to failure to form effective antibodies.