One week after public schools opened for the new school year, New York City Mayor Bill de Blasio announced new changes to student testing.

Starting Sept. 27, students in all grade levels will be tested weekly instead of bi-weekly. In addition, any student who is in a classroom with a positive case won't have to quarantine if they were masked and three feet distant, according to the mayor.

"We've been looking at these two issues over the last few weeks. We looked at it in light of the data from the first week of school, we decided to make both of these changes simultaneously, and they do complement each other," de Blasio said during his daily news conference.

The United Federation of Teachers had pushed the mayor to switch to weekly testing. All teachers must have at least one dose of the COVID-19 vaccine by Sept. 27, as part of the city's mandate for education employees.

CVS Health is launching a major hiring spree to fill 25,000 clinical and retail jobs in preparation for an expected increase in vaccine and testing demand in the months ahead.

The move is in anticipation of the need for COVID-19 booster shots and flu vaccines.

The positions will largely be for pharmacists, pharmacy technicians and nurses at their retail locations to be filled “as soon as possible,” the company announced Monday.

Pharmacy executives predict a far greater staffing need than usual this year, especially should flu season get severe and if COVID-19 boosters become authorized for more expanded groups. Pharmacies are also hoping to avoid a repeat of last year’s scenes of slammed testing sites and the chaotic start to the vaccine rollout.

“Every flu season we need additional team members,” said Neela Montgomery, the executive vice president of CVS health and the president of CVS Pharmacy. “But this year we’re looking for even more. With the continued presence of COVID-19 in our communities, we’re estimating a much greater need for pharmacists, trained pharmacy technicians, nurses, and retail store associates. These jobs offer a rewarding opportunity to really make an impact on public health in our country.”

A virtual hiring event Friday will spearhead the recruiting push.

-ABC News’ Sasha Pezenik

There is still uncertainty and questions to be answered regarding whether all Americans will be recommended to receive booster shots of the COVID-19 vaccine, said acting U.S. Food and Drug Administration Commissioner Dr. Janet Woodcock.

Woodcock spoke with former senior White House COVID-19 response adviser Andy Slavitt on his podcast program “The Bubble” on Monday, raising questions on what the booster shots may or may not do and discussing any uncertainties that could have factored into the FDA’s decision to recommend boosters only for high-risk Americans and those over the age of 65.

Right now, the FDA does not know enough about how an additional shot will impact transmissibility or about cellular immunity and whether T-cells are protected, among other factors, Woodcock said.

“Basically the FDA decision is, do the overall benefits outweigh the potential harms for any given vaccination and that’s how to proceed,” Woodcock said. “But obviously individuals benefit from not having a transmissible virus circulating around."

-ABC News’ Matthew Vann

In the wake of weeks of increasing COVID-19 cases and hospitalizations, the U.S. is once again experiencing a surge in virus-related deaths.

The average number of deaths in the U.S. has risen to more than 1,500 per day, an increase of about 20% in the last week and nearly eight times the death average from two months ago, when the national average dropped to a near-low of 191 deaths reported each day, according to data from the CDC and the Department of Health & Human Services.

Twenty-two states and Washington, D.C. are seeing increasing case averages, while seven states are experiencing increasing hospital admissions, according to the HHS.

However, overall hospitalizations in the U.S. are down, with about 10,000 fewer patients currently hospitalized compared to three weeks ago.

About 93,000 Americans are currently hospitalized. In recent weeks, there had been more than 103,000 patients receiving care across the country.

The drop is largely attributed to plummeting figures in Florida, where there are nearly 10,000 fewer patients hospitalized now, compared to a month ago.

The presence of the virus is shifting away from states in the deep South such as Florida, Louisiana and Mississippi, and further into other regions of the country that were not as hard hit in the first delta surge.

Tennessee and West Virginia currently have the country's highest case rate, followed by Alaska, South Carolina, Wyoming, Montana and Kentucky, which all have case rates above 500 per 100,000 people.

-ABC News’ Arielle Mitropoulos

In a letter to the Texas Education Agency, the U.S. Department of Education on Tuesday said it is beginning an investigation into Texas schools' ban on mask mandates, and how that could potential be an infringement of students’ civil rights.

The investigation will focus on "whether, in light of this policy, students with disabilities who are at heightened risk for severe illness from COVID-19 are prevented from safely returning to in-person education, in violation of Federal law,” the letter states.

The Department of Education’s acting assistant secretary for civil rights, Suzanne Goldberg, laid out the process of the investigation in the letter, but also made clear that it could be resolved at any time if masks in schools are reinstated.

"OCR’s Case Processing Manual provides several ways for this investigation to be resolved, including an option to reach a voluntary resolution agreement prior to the completion of an investigation,” the letter reads. “If TEA expresses an interest in resolving the investigation in this way and OCR determines this form of resolution is appropriate based on the investigation, we will follow the steps set out in Section 302 of the Case Processing Manual.”