Abstract
From 21 January 2020 to 9 February 2020, three family clusters involving 31 patients with coronavirus disease 2019 were identified in Wenzhou, China. The epidemiological and clinical characteristics of the family cluster patients were analysed and compared with those of 43 contemporaneous sporadic cases. The three index cases transmitted the infection to 28 family members 2-10 days before illness onset. Overall, 28 of the 41 sporadic cases and three of 31 patients in the family clusters came back from Wuhan (65.12 vs. 9.68%, P< 0.001). In terms of epidemiological characters and clinical symptoms, no significant differences were observed between the family cluster and sporadic cases. However, the lymphocyte counts of sporadic cases were significantly lower than those of family cluster cases ((1.32 ± 0.55) × 109/l vs. (1.63 ± 0.70) × 109/l, P = 0.037), and the proportion of hypoalbuminaemia was higher in sporadic cases (18/43, 41.86%) than in the family clusters (6/31, 19.35%) (P < 0.05). Within the family cluster, the second- and third-generation cases had milder clinical manifestations, without severe conditions, compared with the index and first-generation cases, indicating that the virulence gradually decreased following passage through generations within the family clusters. Close surveillance, timely recognition and isolation of the suspected or latent patient is crucial in preventing family cluster infection.
Highlights
Since December 2019, an epidemic of coronavirus disease 2019 (COVID-19), associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in Wuhan, Hubei province, China [1, 2]
The first family clustering study reported that five family members who travelled to Wuhan from Shenzhen were infected with SARS-CoV-2, and when they returned to Shenzhen, the additional family members who did not travel to Wuhan became infected with the virus [6]
The epidemiological and clinical characteristics of three family clusters were investigated using sporadic patients as controls. Such a specific population provides us an opportunity to analyse the relationship between transmission and the disease presentation in different settings where the sporadic patients were used as external controls to the family cluster patients
Summary
Since December 2019, an epidemic of coronavirus disease 2019 (COVID-19), associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in Wuhan, Hubei province, China [1, 2]. The epidemic of COVID-19 has rapidly spread to the whole country and worldwide. As of 26 March 2020, 195 countries had been affected, and the cumulative number of confirmed cases had reached 81 968 and 389 199 in China and worldwide, with 3293 and 17 914 deaths, respectively. The epidemiological characteristics of COVID-19, especially transmission patterns, have not been well elucidated. Several studies reported the family cluster transmission resulting in the infection of 3–11 family members [7,8,9,10,11], even during the incubation period. Further investigation is required to understand the transmission patterns among family members
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