You mean OAS? That can happen yes and is theorised to be why flu gets deadlier as people get older, their immune system gets more and more confused by memories

You mean OAS? That can happen yes and is theorised to be why flu gets deadlier as people get older, their immune system gets more and more confused by memories of flus from people's youth. In this case, the problem is that it accelerates the spread. Normally in any epidemic there's a large population of people who were never infected, so it's their first time and the body becomes highly immune. They act as buffers that stop the virus from spreading so fast to those unlucky enough to have got the earlier version. You end up with a diverse population of people immune to different variants which slows them all down. If you fix everyone on a variant that hasn't existed for years then this buffering effect is eliminated. Everyone becomes equally vulnerable to reinfection. This is posited as the explanation for why do many vaccinated people seem to be susceptible to rapid reinfection. Although it can be happen naturally too, the wider social diversity that would make that happen say every few years is gone, so now it can happen every few months instead.