Impact of Age and Symptom Development on SARS-CoV-2 Transmission in Households With Children—Maryland, New York, and Utah, August 2020–October 2021

A new Centers for Disease Control and Prevention (CDC) study of COVID-19 transmission in households with children shows little difference in transmission rates between vaccinated and unvaccinated people. But the study, for which Abt Global was a collaborator, provides further confirmation that vaccination reduces the chances of acquiring an infection and that isolation of people with COVID-19 reduces transmission within households.

The study, conducted before the emergence of the Omicron variant and vaccines for children in the United States, found that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, was transmitted from people of all ages and from those with or without symptoms. However, staying in a separate room from other household members while sick significantly reduced the odds of transmission to another household member. The findings highlight how important CDC-recommended medical and non-medical prevention steps are for everyone to control transmission and prevent infection in households.

The study used data from 513 households and 2.053 people. Researchers collected the data from participants in the the Coronavirus Household Evaluation and Respiratory Testing study from August 2020 to August 2021 for households in Utah and from September 2020 to August 2021 for those in New York City. The study also included data from the SARS-CoV-2 Epidemiology And Response in Children study in Maryland, with data collected from November 2020 to October 2021.

Participants collected and submitted nasal swabs weekly and with onset of acute illness. The study, which followed participants through the Alpha and Delta waves, captured both asymptomatic and symptomatic infections with SARS-CoV-2. Participants completed weekly surveys, online or via text, about symptoms experienced in the preceding week and, if they had symptoms, what preventive measures they took such as isolating or wearing a mask.

Participants in the study included researchers from Abt, CDC, Bloomberg School of Public Health at Johns Hopkins University, Vagelos College of Physicians and Surgeons at Columbia University, University of Utah School of Medicine, and Marshfield Clinic Research Institute.