A study that’s causing public health officials to grow more concerned about COVID spreading between loved ones is based primarily on families in Nashville. Researchers hope it’ll reveal the most common ways relatives and roommates get each other sick.
The existing research on household transmission of COVID-19, like this study from New York, mostly relies on looking back at contact tracing data, which can have big holes. So Dr. Carlos Grijalva, a Vanderbilt University epidemiologist, decided he would create his own data set.
His research team has now followed nearly 200 households, mostly in Nashville with some also with a research site in Wisconsin. When one person gets sick, they get consent from the patient and members of the household, then begin interviewing them and taking nasal swabs and collecting saliva for 14 days.
“That was the intention, to have a very systematic assessment with this very systematic surveillance with repeated daily measures and collection of daily samples,” Grijalva says.
Until now, most of the studies about household transmission have been done abroad in countries like China where some countries even remove the infected patient from the home to isolate.
“We were not sure if that was the same scenario here in the United States,” he says.
Instead of finding 10% to 20% of household members getting sick from the first patient in a household, Grijalva’s team found that in Nashville the transmission rate was more like 50%. So if a family of five has someone fall ill, two other people on average are going to contract COVID too.
Nashville health officials have increasingly identified transmission in the home as a factor that’s mostly out of their control.
The Centers for Disease Control and Prevention rushed to publish the preliminary findings on Friday, but the project is ongoing so they can draw more specific conclusions. Grijalva hopes to identify factors that may facilitate transmission — and those that may prevent it.