Background: Global outbreak of novel coronavirus 2019 (COVID-19) continues to constitute a public health emergency of international concern. However, few studies have directly compared the differences of clinical features and outcomes between imported and non-imported COVID-19 patients. We aimed to directly compare the differences of clinical features and outcomes between imported and non-imported COVID-19 patients.
Methods: we enrolled 275 patients (53 imported and 222 non-imported cases) with laboratory-confirmed COVID-19 from four designated hospitals in Chongqing, China. Epidemiological, demographic, clinical, laboratory, treatment, and outcome data were collected and analyzed. Independent samples t- test, Mann- Whitney U test, Wilcoxon test,χ2 test, or Fisher’s exact test were adopted to compare the difference between imported and non-imported groups where appropriate
Results: The imported group had a higher proportion of asymptomatic patients (18.9% vs. 3.8%, p=0.016), lower lymphocyte count (1.1×109/L vs. 1.5×109 /L, p=0.018), higher neutrophil-to-lymphocyte ratio (NLR) (2.6 vs. 2.3, p=0.0237), higher proportion of CD4+ T cells reduction (70% vs. 44.6%, p=0.043), longer duration of viral shedding (20 days vs. 18 days, p = 0.0416) than the non-imported group. The symptomatic non-imported group had a lower lymphocyte count (1.3×109/L vs. 1.6×109 /L, p=0.003), lower CD4+ and CD8+ T cells, longer viral shedding (20 days vs.13 days, p< 0.001) and hospital stay (17 days vs.14 days, p=0.015) than the asymptomatic non-imported group. Furthermore, when compared with imported group, asymptomatic non-imported group showed higher lymphocyte count (1.6×109/L vs. 1.1×109 /L, p< 0.001) and CD4+ T cells(567 vs.375, p=0.029), while the symptomatic non-imported group showed no difference in lymphocyte count, CD4+ or CD8+ T cells (p ≥ 0.0894).
Conclusion: Our results indicated that when compared with imported patients, damage to the immune system by SARS-Cov-2 in non-imported patients was milder, and this might be mainly due to its higher asymptomatic proportion.
Clinical trial registration: ChiCTR2000033980. Registered 19 June 2020 - Retrospectively registered, http:// www.chictr.org.cn.