Features of family clusters of COVID-19 patients: A retrospective study

To investigate and compare the clinical and imaging features among family members infected with COVID-19.

We retrospectively collected a total of 34 COVID-19 cases (15 male, 19 female, aged 48 ± 16 years, ranging from 10 to 81 years) from 13 families from January 17, 2020 through February 15, 2020. Patients were divided into two groups: Group 1 - part of the family members (first-generation) who had exposure history and others (second-generation) infected through them, and Group 2 - patients from the same family having identical exposure history. We collected clinical symptoms, laboratory findings, and high-resolution computed tomography (HRCT) features for each patient. Comparison tests were performed between the first- and second-generation patients in Group 1.

In total there were 21 patients in Group 1 and 20 patients in Group 2. For Group 1, first-generation patients had significantly higher white blood cell count (6.5 × 10⁹/L (interquartile range (IQR): 4.9-9.2 × 10⁹/L) vs 4.5 × 10⁹/L (IQR: 3.7-5.3 × 10⁹/L); P = 0.0265), higher neutrophil count (4.9 × 10⁹/L (IQR: 3.6-7.3 × 10⁹/L) vs 2.9 × 10⁹/L (IQR: 2.1-3.3 × 10⁹/L); P = 0.0111), and higher severity scores on HRCT (3.9 ± 2.4 vs 2.0 ± 1.3, P = 0.0362) than the second-generation patients. Associated underlying diseases (odds ratio, 8.0, 95% confidence interval: 3.4-18.7, P = 0.0013) were significantly correlated with radiologic severity scores in second-generation patients.

Analysis of the family cluster cases suggests that COVID-19 had no age or sex predominance. Secondarily infected patients in a family tended to develop milder illness, but this was not true for those with existing comorbidities.