“Your body will usually produce one type of antibody called IgM in the week or 10 days after you have been exposed to a virus. “About two weeks after exposure, you should have another type of antibody, the IgG.”
But according to this thread from David States, Chief Medical Officer, Affigen, Inc.,"Lots of people don’t develop much of an IgM response and the IgG response fades noticeably after just two months..." https://threadreaderapp.com/thread/1252698777296797698.html