Clinical characteristics of COVID-19 patients in three consecutive generations of spread in Zhejiang, China

OBJECTIVES: The aim was to determine the clinical characteristics of COVID-19 patients because the SARS-CoV-2 virus continues to circulate in the population. METHODS: This is a retrospective, multicentre, cohort study. Adult COVID-19 cases from four hospitals in Zhejiang were enrolled and clustered into three groups based on epidemiological history. First-generation patients had a travel history to Hubei within 14 days before disease onset; second-generation patients had a contact history with first-generation patients; third-generation patients had a contact history with second-generation patients. Demographic, clinical characteristics, clinical outcomes and duration of viral shedding were analysed. RESULTS: A total of 171 patients were enrolled, with 83, 44 and 44 patients in the first-, second-, and third-generation, respectively. Compared with the first and second generations, third-generation patients were older (61.3 vs. 48.3 and 44.0 years, p < 0.001) and had more coexisting conditions (56.8% vs. 36.1% and 27.3%, p 0.013). At 7 ± 1 days from illness onset, third-generation patients had lower lymphocyte (0.6 vs. 0.8 and 0.8 × 109/L, p 0.007), higher C-reactive protein (29.7 vs. 17.1 and 13.8 mg/L, p 0.018) and D-dimer (1066 vs. 412.5 and 549 μg/L, p 0.002) and more lesions involving the pulmonary lobes (lobes ≥5, 81.8% vs. 53.0% and 34.1%, p < 0.001). The proportions of third-generation patients developing severe illness (72.7% vs. 32.5% and 27.3%, p < 0.001), critical illness (38.6% vs. 10.8% and 6.8%, p < 0.001) and receiving endotracheal intubation (20.5% vs. 3.6% and 2.3%, p 0.002) were higher than in the other two groups. DISCUSSION: Third-generation patients were older, had more underlying comorbidities and had a higher proportion of severe or critical illness than first- and second-generation patients.