A new study from the Centers for Disease Control and Prevention says that many Americans who tested positive for COVID-19 weren’t able to identify the source of their infection.

The findings revealed that a full 54% of those who contracted the disease couldn’t recall having contact with an infected person.

According to Live Science, the study suggests that many people may be getting infected in their communities, and not from someone they know. The CDC conducted telephone interviews with 350 adults in 9 states who tested positive for the virus between May 31 and May 10 of this year.

According to Medical Daily, researchers said that their study highlights the importance of isolating those who are infected as well as stepping up testing and contact tracing.

The study also confirmed that minority and low-income populations were at higher risk of contracting COVID-19, and that older patients were the ones most likely to be hospitalized, according to Live Science.

The researchers suggested that governments implement prevention measures, including social distancing and wearing masks in public places to help prevent transmission of the virus and slow down the spread of disease, according to Medical Daily.