Differences in Immune Responses between Children and Adults with COVID-19

Abstract

Over 85 590 000 individuals have been infected with severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2). Although there have been an increasing number of reports on coronavirus disease 2019 (COVID-19), it is unclear why infected children show milder symptoms than adults. A retrospective case study was performed at two designated hospitals for COVID-19. Patients (56 children and 63 adults) with confirmed SARS-CoV-2 infection and mild pneumonia were randomly enrolled in this study. The median age of the children was 7.0 years, and 51.79% of them were boys. The median age of the adults was 57 years, and 47.62% were men. The most common symptoms were fever, cough, sputum and diarrhoea. There were no significant differences in symptoms between children and adult patients. In terms of immunological indices on admission, adult patients displayed typical leukopenia and markedly higher levels of IL-2, IL-4, and IL-6 than child patients. The elevation of IL-2, IL-4 and IL-6 in adults induced more extensive lung injury. The effective and non-aggressive immune response successfully resisted SARS-CoV-2 invasion and maintained mild symptoms in child patients. The correlation of higher IL-2, IL-4, and IL-6 with the lung injury might be evidence that preventing excessive cytokine production can avoid further lung damage in these patients.

Keywords

COVID-19 / child / adult / immune response

References

[1] HuangC, WangY, LiX, et al.. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet, 2020, 395(10223): 497-506

[2] ChanJF, YuanS, KokKH, et al.. A familial cluster of pneumonia associated with the 2019 novel coronavirus indicating person-to-person transmission: a study of a family cluster. Lancet, 2020, 395(10223): 514-523

[3] GuanWJ, NiZY, HuY, et al.. Clinical characteristics of coronavirus disease 2019 in China. N Engl J Med, 2020, 382(18): 1708-1720

[4] ChenG, WuD, GuoW, et al.. Clinical and immunological features of severe and moderate coronavirus disease 2019. J Clin Invest, 2020, 130(5): 2620-2629

[5] ShenKL, YangYH, WangTY. Diagnosis, treatment, and prevention of 2019 novel coronavirus infection in children: experts’ consensus statement. World J Pediatr, 2020, 16(3): 223-231

[6] New coronavirus pneumonia prevention and control program (6th ed.) (in Chinese). 2020(http://www.nhc.gov.cn/yzygj/s7653p/202002/8334a8326dd94d329df351d7da8aefc2/files/b218cfeb1bc54639af227f922bf6b817.pdf).

[7] WuP, HaoX, LauE, et al.. Real-time tentative assessment of the epidemiological characteristics of novel coronavirus infections in Wuhan, China, as at 22 January 2020. Euro Surveill, 2020, 25(3): 2000044

[8] ShiH, HanX, JiangN, et al.. Radiological findings from 81 patients with COVID-19 pneumonia in Wuhan, China: a descriptive study. Lancet Infect Dis, 2020, 20(4): 425-434

[9] PittetJF, GriffithsMJ, GeiserT, et al.. TGF-beta is a critical mediator of acute lung injury. J Clin Invest, 2001, 107(12): 1537-1544