For the third straight day, Florida and South Carolina broke their single-day records for new cases, while infection levels for Missouri and Nevada also reached new highs on Saturday.

On Friday, the US reported more than 30,000 new infections, its highest total since May 1, with cases rising in 19 states across the South, West and Midwest.

Florida reported 4,049 new cases on Saturday, breaking Friday’s record (3,822) and Thursday’s record (3,207). The state now has had 93,797 cases and 3,144 deaths. South Carolina broke its record with 1,155 new cases; Nevada had 452 and Missouri had 375.

The new infections have skewed younger, with more people in their 20s and 30s testing positive, governor Ron DeSantis of Florida said.

Southern officials in particular are speaking out with increasing alarm about the large number of cases turning up in young adults.

At least 100 cases were linked on Friday to employees and customers of bars in the Tigerland nightlife district near the Louisiana State University campus.

In South Carolina, cases among people who are 21 to 30 have grown 413 per cent since April 4. In Mississippi, state officials said several cases had been tied to fraternity rush parties in Oxford, home to the University of Mississippi. More than 80 per cent of new cases in Oxford involved people 18 to 24.

In South Carolina, officials warned that some young people had become seriously ill from the virus and that those without serious symptoms could still infect family members and friends.