Experts worry a recent rise in long COVID cases — fueled by a spike in winter holiday infections and a decline in masking and other measures — could continue into this year.

A sudden rise in long COVID in January has persisted into a second month. About 17.6% of those surveyed by the Census Bureau in January said they have experienced long COVID. The number for February was 17.4.

Compare these new numbers to October 2023 and earlier, when long COVID numbers hovered between 14% and 15% of the US adult population as far back as June 2022.