I've said there most likely has to be something besides viral particles for the long term response seen in longhaulers and CFS. If all longhaulers were presenting antigens there's a possibility that the antigens went over to an autoimmune response. So that's either not the case or current tests are not detecting the rogue antigens.

The other thing that comes to mind would be a genetic mutation caused by the live virus that either increases immune activity or dampens anti-inflammatory factors.