CNN  — 

The surge of Covid-19 fueled by the Delta variant and low vaccination rates is sending the country backward in the pandemic, with hospitalizations reaching wintertime levels.

For the first time since February 27, more than 50,000 Covid-19 patients were hospitalized Monday, according to data from the US Department of Health and Human Services.

The 50,625 hospitalizations were more than triple the number from one month ago, when about 16,000 patients were hospitalized.

At this point, it might not be possible to reach herd immunity, the director of the National Institutes of Health said. At the current pace of vaccinations, it will take until mid-February to reach all of the remaining eligible people with at least one dose, a CNN analysis of Centers for Disease Control and Prevention data found.