Epidemiological Trends of COVID-19 Infection and Symptom Incidence in China Following the Adjustment of Zero-COVID Policy: A Prospective, Community-Based Cohort Study.

This study tracked the postadjustment infection rates and symptom trends within community settings. Conducted from May 2023 to May 2024 across four districts in Shenzhen, involving 3246 participants, over 80% had received at least one vaccine dose. Postpolicy adjustment witnessed three significant infection surges. Among the cohort, 63.7% reported only one Coronavirus disease 2019 (COVID-19) infection, 30.3% two infections, and 1.7% three infections, with 4.3% remaining uninfected throughout the follow-up. Older adults and those with lower IgG levels had increased reinfection risk. Notably, 3.8% (95% CI: 3.1-4.6) reported long COVID, with higher susceptibility in those with underlying conditions (adjusted odds ratio [AOR] = 3.73, 95% CI: 2.20-6.34) and reduced incidence among fully vaccinated individuals (AOR = 0.57, 95% CI: 0.36-0.90). The policy change led to widespread exposure, shifting from first infections to reinfections. These insights underscore the need for ongoing research to inform future pandemic responses.