Background. Bacterial/fungal superinfections are commonly reported to complicate severe influenza viral community-acquired pneumonia (CAP). However, there is limited knowledge of superinfections among patients with other respiratory viruses, especially in those with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods. From December 2017 to February 2020, we enrolled 255 of 528 eligible adults with viral CAP. Respiratory viruses were detected by multiplex RT-PCR. Results. Eighty-eight (34.5%) of viral CAP-associated hospitalizations had evidence of bacterial/fungal superinfection. The incidence and types of bacterial/fungal infections with non-influenza respiratory viruses were analogous to that associated with influenza, except for patients with SARS-CoV-2 infection. Superinfections complicated the clinical outcome of patients with viral pneumonia, by presenting with significantly more in-hospital mortality than those without (22.7% vs 2.4%, P < 0.0001). In the follow-up period, the incidence of death within 120 days after admission was significantly higher in patients with bacterial/fungal superinfection (HR = 9.708, P < 0.0001) than in those without. Furthermore, we found that PaO2/FiO2 < 300 (OR: 2.570, 95% CI: 1.370-4.821, P = 0.003), BUN ≥ 7.1 mmol/L (OR: 4.016, 95% CI: 2.148-7.509, P < 0.001), leukocytosis (OR: 2.769, 95% CI: 1.335-5.741, P = 0.006) and lymphocytopenia (OR: 1.998, 95% CI: 1.086-3.675, P = 0.026) were independent risk factors of superinfection. Conclusions. Mixed viral-bacterial/fungal CAP was associated with a higher mortality rate than the primary viral infection. PaO2/FiO2 < 300, BUN ≥ 7.1 mmol/L, leukocytosis, and lymphocytopenia were independent risk factors for superinfection.