A study from Bergen shows higher household secondary attack rate of Covid-19 than a Chinese study.
We read with interest the Article by Qifang Bi and colleagues, in which they reported a household secondary attack rate, as detected by repeated RT-PCR tests, of approximately 11%.
We have found substantially higher attacks rates in western Norway through detection of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
Of 158 cases, 125 (79%) tested positive for antibodies and 12 (8%) were defined as borderline.
In 77 household members, 24 (31%) tested positive and two (3%) were borderline. Our results show that detection of seroconversion might provide a more accurate picture of attack rates in households than intermittent RT-PCR testing.