Figure 2.

Severe acute respiratory syndrome coronavirus 2 viral burden is correlated within families. The viral load obtained at enrollment from nasopharyngeal (NP) swabs in households with multiple COVID-19–positive household members is shown (n = 42 households). Each vertical row in red depicts an individual household, with circles delineating the log viral load of each member within the household. Gray-shaded circles represent values derived from a nasal midturbinate swab if NP sampling was not performed. This was based on a linear regression equation generated from more than 100 study participants with positive viral load from both NP and nasal midturbinate swabs [11]. Households are depicted across the x-axis in order of decreasing viral load. Data drawn from 148 participants. The intraclass correlation coefficient  = 0.45; 95% confidence interval, .23–.62; P value < .001. Abbreviation: COVID-19, coronavirus disease 2019.