COVID-19 updates: 345 children currently hospitalized with coronavirus in Texas

Mississippi has the country's highest COVID-19 case rate, followed by Florida, Kentucky and Louisiana, according to federal data.

With more than 101,000 Americans now hospitalized with COVID-19, the U.S. is steadily approaching its hospitalization peak from early January, when more than 125,000 patients were hospitalized at one time, according to federal data.

A little over two months ago, less than 12,000 patients were in U.S. hospitals, according to federal data.

But there has been improvement when it comes to vaccinations.

One week after the FDA fully approved the Pfizer vaccine, initial data from an ABC News analysis indicates that the U.S. has seen a slight uptick in the average number of Americans going out to get their first vaccine dose.

In the week prior to the full approval, an average of about 404,000 Americans were initiating vaccination each day. Now, about 473,000 Americans are getting their first shot each day -- a 17% increase.

-ABC News' Arielle Mitropoulos

Fifteen people were charged Tuesday in what the Manhattan District Attorney’s Office called a fake vaccine card conspiracy.

Among those charged is a woman who allegedly sold 250 fake cards on Instagram, believed to be among the first alleged seller of phony vaccine cards charged in
the country. 

Manhattan District Attorney Cy Vance said in a statement, "We need companies like Facebook to take action to prevent the fraud happening on their platforms."

-ABC News' Aaron Katersky

New York Gov. Kathy Hochul said Tuesday that unvaccinated public and charter school employees must undergo weekly testing.

"I think that's a compromise,” she said.

Hochul is also working to establish vaccine requirements for all staff at state-regulated facilities and congregate settings. New York officials announced last week that all health care facility staff must be vaccinated.

-ABC News' Aaron Katersky

Fully vaccinated immunocompromised individuals still produce immunity, but at reduced levels compared to healthy individuals, according to a study released Monday by the American College of Physicians.

Researchers at the Washington University School of Medicine compared antibody responses between 133 immunosuppressed and 53 healthy participants between Dec. 10, 2020, and March 20. The study looked at mRNA COVID-19 vaccines produced by Pfizer and Moderna.

The study's main findings found reduced antibody levels in the immunosuppressed group, particularly those taking steroids and specific drugs depleting white blood cells.

Researchers said the study emphasizes the need for booster shots among immunocompromised patients.

-ABC News' Alexis E. Carrington