A multi-institution study published by the Centers for Disease Control and Prevention suggests the portion of adults reporting long COVID-19 symptoms has dropped.

It also says one in four people with the illness still report being unable to fully carry out daily activities.

The study takes a registry of symptoms self-reported at three-month intervals and cross-references it with data from the National Center for Health Statistics and the Census Bureau’s Household Pulse Survey, which track social and economic effects of COVID-19 in the U.S.

In most cases, COVID-19 symptoms decreased after initial illness. But about 16% of participants described ongoing or emerging symptoms up to one year later.

The authors say awareness of the persistence, emergence or reemergence of symptoms over time can help health care providers understand the clinical signs and symptoms of long COVID-19.