PAO-YU CHENWu, Tzong-YowTzong-YowWuJANN-TAY WANGWANG-DA LIUYEE-CHUN CHENSHAN-CHWEN CHANG2025-10-272025-10-272025-10https://scholars.lib.ntu.edu.tw/handle/123456789/732919Background: Emerging studies link COVID-19 to adverse multi-organ outcomes. To better estimate psychiatric and physical illness after the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, we analyzed a nationally representative cohort with minimal prior infection (>99% uninfected) and low vaccination coverage (<1%) in Taiwan. Methods: We conducted a cohort study comprising 11,185 individuals who survived the first 30 days following SARS-CoV-2 infection (alpha variant) between May 1, 2021, and September 30, 2021, confirmed by reverse transcription polymerase chain reaction, along with three age- and sex-matched comparison groups: a contemporary control group (n = 223,700) with no COVID-19 diagnosis, a historical control group (n = 223,700) predating the pandemic, and seasonal influenza group (n = 44,740). We calculated the adjusted incidence rate ratios (aIRRs) of specific psychiatric and physical illnesses to compare their occurrence between the COVID-19 cohort and comparison groups. Results: During the 6 months after the first COVID-19 diagnosis, aIRRs for psychiatric illnesses in the COVID-19 group were higher across diagnostic categories than those of comparison groups. Moreover, aIRRs of physical illnesses in the COVID-19 group were higher across nearly all major organ systems compared to the comparison ones. The absolute rate difference for overall psychiatric illnesses was 7921.0 (COVID-19 vs contemporary control) and 7226.9 per 100,000 person-years (COVID-19 vs historical control), respectively. Conclusions: SARS-CoV-2-immunologically naïve individuals have heightened risks of psychiatric illnesses across diagnostic categories and physical illnesses spanning nearly all major organ systems after the infection. Future studies warrant to explore the pathogenesis of these postacute effects.en[SDGs]SDG3letter10.1016/j.jfma.2025.06.01940651844