The characteristics of household transmission of COVID-19

Clin Infect Dis. 2020 Apr 17;ciaa450. doi: 10.1093/cid/ciaa450. Online ahead of print.

Abstract

Background: Since December 2019, SARS-CoV-2 virus has extended to most parts of China with more than 80 thousand cases and to at least 100 countries with more than 60 thousand international cases by March 15, 2020. Here we applied household cohort study to determine the features of household transmission of COVID-19.

Methods: Total 105 index patients and 392 household contacts were enrolled. Both index patients and household members were inspected by SARS-CoV-2 RT-PCR. The information of all recruited people was extracted from medical records and confirmed or supplemented by telephone interviews. The baseline characteristics of index cases and contact patients were described. Secondary attack rates of SARS-CoV-2 to the contact members were computed and the risk factors for transmission within household were estimated.

Results: Secondary transmission of SARS-CoV-2 developed in 64 of 392 household contacts (16.3%). The secondary attack rate to children was 4% comparing with 17.1% to adults. The secondary attack rate to the contacts within the households with index patients quarantined by themselves since onset of symptoms was 0% comparing with 16.9% to the contacts without index patients quarantined. The secondary attack rate to contacts who were spouses of index cases was 27.8% comparing with 17.3% to other adult members in the households.

Conclusion: The secondary attack rate of SARS-CoV-2 in household is 16.3%. Ages of household contacts and spouse relationship with index case are risk factors for transmission of SARS-CoV-2 within household. Quarantine of index patients at home since onset of symptom is useful to prevent the transmission of SARS-Co-2 within household.

Keywords: Household transmissionCOVID-19Novel coronavirus pneumoniaSARS-CoV-2.