Household Transmission of SARS-CoV-2 Common
Transmission common when index patient is adult or child; most secondary infections occur within five days
TUESDAY, Nov. 3, 2020 (HealthDay News) -- Household transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is common and occurs rapidly after onset of the index patient's illness, according to research published in the Oct. 30 early-release issue of the U.S. Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report.
Carlos G. Grijalva, M.D., from the Vanderbilt University Medical Center in Nashville, Tennessee, and colleagues examined household transmission in a case-ascertained study conducted in Nashville, Tennessee, and Marshfield, Wisconsin, starting in April 2020. Index patients, defined as the first household members with COVID-19-compatible symptoms who received a positive SARS-CoV-2 test result, and household members were trained to complete symptom diaries and obtain self-collected specimens for 14 days. Specimens from the first seven days were tested for SARS-CoV-2.
The researchers found that on the days of the index patient's illness onset, 191 household contacts of 101 index patients reported having no symptoms. During follow-up, 102 of the 191 contacts had SARS-CoV-2 detected in nasal or saliva specimens, for a secondary infection rate of 53 percent. In 14 households with an index patient younger than 18 years, the secondary infection rates were 53 and 38 percent, respectively, from index patients younger than 12 years and aged 12 to 17 years. Within five days of the index patient's illness onset, about 75 percent of secondary infections were identified; transmission was substantial regardless of whether the index patient was an adult or a child.
"These findings suggest that transmission of SARS-CoV-2 within households is high, occurs quickly, and can originate from both children and adults," the authors write.