This study found that the secondary attack rate of SARS-CoV-2 in households was 16%. Spouses were at highest risk.

This cohort study sought to determine the features of household transmission of COVID-19. Researchers examined 105 index patients and 392 household contacts, all of whom were tested by SARS-CoV-2 RT-PCR.

They found that secondary transmission of SARS-CoV-2 occurred in 16% household contacts. This was further described as 4% in children and 17% in adults. The secondary attack rate for contacts in households where index patients quarantined by themselves was 0%, compared to 17% of contacts without index patients quarantined. The secondary attack rate of spouses of index cases was 28% compared to 17% of other adult members in households.