Epidemiological and Clinical Characteristics of COVID-19 in Adolescents and Young Adults

Abstract

Background: Adolescents and young adults might play a key role in the worldwide spread of Coronavirus Disease 2019 (COVID-19) because they are more likely to be involved in overseas study, business, work, and travel. However, the epidemiological and clinical characteristics remain unknown.

Methods: We collected demographic, epidemiological, and clinical data from 46 confirmed COVID-19 patients aged 10 to 35 years from the Chongqing Three Gorges Central Hospital. Several key epidemiological parameters, asymptomatic cases, transmission to family members, and clinical characteristics at admission and during treatment were summarized.

Results: Of 46 confirmed patients, 14 patients (30.4%) were aged between 10 and 24 years, and 24 (52.2%) patients were male. The estimated mean incubation period was 6.6 days (95% confidence interval [CI] 4.4-9.6). The median serial interval was 1.9 days (95% CI 0.4-6.2). Three of the asymptomatic cases showed transmission to their family members. Only one patient was identified as a severe case at admission. The common symptoms at admission were dry cough (34, 81.0%) and fever (29, 69.1%). Nearly 60% of the patients showed ground-glass opacity on chest computed tomography. Three patients developed acute kidney injury during treatment. Most of the patients (78.3%) recovered and were discharged by the end of the follow-up.

Conclusions: This single-center study with a relatively small sample size showed that adolescent and young adult patients with COVID-19 had a long incubation period and a short serial interval. The transmission occurred from asymptomatic cases to family members. Fewer patients developed complications during treatment.

Keywords: COVID-19; adolescents and young adults; epidemiological and clinical characteristics.

Graphical abstract

Figure 1

Chest Computed Tomography Images of Study Patients Infected with COVID-19 (A and B) Chest CT images of lung window and mediastinum window from a patient aged 21 years on day 10 after illness onset. (C and D) Chest CT images of lung window and mediastinum window from a patient aged 33 years on day 14 after illness onset.

Figure 2

Information on Exposures and Dates of Illness Onset in Six Symptomatic Cases and Their Family Close Contacts Numbers in boxes are calendar dates. Data from the 12 secondary cases (close contacts were defined as those who had clear exposure to only one index case and had no other potential source of infection) were used to estimate the distribution of serial interval.

Figure 3

Key Distributions of Epidemiological Characteristics for Study Patients (A) Estimated serial interval distribution. (B) Estimated incubation period distribution for symptomatic cases and asymptomatic cases truncated at hospitalization. (C) Estimated incubation period distribution only for asymptomatic cases. (D) Estimated distributions of times from illness onset to first medical visit.

Figure 4

Progress of Clinical Symptoms and Chest CT Findings during Treatment Periods for Four Asymptomatic Cases and Their Family Contacts Numbers in boxes are calendar dates. The symptoms and chest CT findings related to COVID-19 are indicated in onset dates by black arrows.