Delivery of infection from asymptomatic carriers of COVID-19 in a familial cluster

Int J Infect Dis. 2020 May;94:133-138. doi: 10.1016/j.ijid.2020.03.042. Epub 2020 Apr 2.


Objectives: With the ongoing outbreak of COVID-19 around the world, it has become a worldwide health concern. One previous study reported a family cluster with an asymptomatic transmission of COVID-19. Here, we report another series of cases and further demonstrate the repeatability of the transmission of COVID-19 by pre-symptomatic carriers.

Methods: A familial cluster of five patients associated with COVID-19 was enrolled in the hospital. We collected epidemiological and clinical characteristics, laboratory outcomes from electronic medical records, and also verified them with the patients and their families.

Results: Among them, three family members (Case 3/4/5) had returned from Wuhan. Additionally, two family members, those who had not traveled to Wuhan, also contracted COVID-19 after contacting with the other three family members. Case 1 developed severe pneumonia and was admitted to the ICU. Case 3 and Case 5 presented fever and cough on days two through three of hospitalization and had ground-glass opacity changes in their lungs. Case 4 presented with diarrhea and pharyngalgia after admission without radiographic abnormalities. Case 2 presented no clinical nor radiographic abnormalities. All five cases had an increasing level of C-reactive protein.

Conclusions: Our findings indicate that COVID-19 can be transmitted by asymptomatic carriers during the incubation period.

Keywords: Asymptomatic carrier; COVID-19; Incubation period; Pneumonia; SARS-CoV-2.

MeSH terms

  • Adult
  • Aged
  • Betacoronavirus*
  • COVID-19
  • Coronavirus Infections / complications
  • Coronavirus Infections / diagnosis
  • Coronavirus Infections / transmission*
  • Cough / etiology
  • Diarrhea / etiology
  • Disease Outbreaks
  • Female
  • Fever / etiology
  • Hospitalization
  • Humans
  • Male
  • Middle Aged
  • Pandemics
  • Pneumonia, Viral / complications
  • Pneumonia, Viral / diagnosis
  • Pneumonia, Viral / transmission*
  • SARS-CoV-2
  • Severity of Illness Index
  • Young Adult