Respiratory Virus Immunological Dynamics in the Post-Pandemic Era of Southeastern China: A Retrospective Serological Investigation.

The COVID-19 pandemic has profoundly reshaped the epidemiological landscape of infectious diseases, yet systematic investigations into post-pandemic respiratory virus dynamics in China remain absent. We conducted a seroepidemiological survey during the inaugural year following China's pandemic policy adjustments, analyzing 1104 specimens from blood donors for pathogen-specific IgG antibodies against SARS-CoV-2, influenza viruses, respiratory syncytial virus (RSV), and human parainfluenza viruses (HPIV). This approach explored and described transmission dynamics, age-stratified immune responses, and potential differences in antibody responses across different SARS-CoV-2 vaccine doses. Our findings suggest that, with the relaxation of intervention measures, conventional respiratory viruses appeared to rebound rapidly, with younger adults exhibiting earlier and more robust antibody responses. Furthermore, the COVID-19 booster dose showed a trend toward enhancing immune responses. These insights provide crucial scientific evidence for understanding post-pandemic respiratory virus epidemiology, guiding vaccine and therapeutic development, and implementing precision public health interventions.