National Illness Indicators Stay Stable

As of May 5, national influenza-like illness (ILI) levels trended sideways with around 0.9% of the population experiencing fevers. The indicator has stayed around the same level since April 18. These are similar levels to 2020 ILI, but well below the 2.7% ILI seen in 2019. 

The rate of transmission (Rt) for fevers has been sitting just below one at 0.99. A level below one indicates continued decreased disease transmission. This level is around the expected value for this metric during an average year.

Another illness metric, long-duration fever (LDF), leveled off at a relatively low number, 0.9%. LDF measures the fevers that last at least 72 hours and is generally an indicator of more severe illness. 

Finally, no age group experienced a significant change in illness levels. The 10-17 and 60+-year-old cohorts continued to have the lowest levels of illness while the 18-25 cohort experienced the most illness.