Antibody detection is a past time test. By detecting the specific antibodies in serum, we can judge whether the subjects have ever been infected with the virus. According to the reports we have and reports from all over the United States, diseases caused by new coronavirus infection may have appeared [in the United States] by mid January, Chris spiters, a Snohomish district health official, said in a statement
The statement said that the positive results of serum antibody test only showed that they had been infected with the new coronavirus before, but could not determine the specific time of infection, so it is difficult to determine whether the above two people were infected with the new coronavirus in December last year, or were infected with other respiratory viruses and then infected with the new coronavirus at that time, but showed no symptoms.
The Department of health in Snohomish district said it has also received dozens of positive reports of serum antibodies against the new coronavirus, which need further investigation.