The number of Delta employees going to the airline's on-site clinic for first vaccine doses has increased more than fivefold Thursday, just 24 hours after the company said it was raising health insurance premiums for unvaccinated employees.

Delta said Wednesday health insurance premiums for unvaccinated employees would go up by $200 per month beginning Nov. 1 to cover COVID-19 costs like potential hospitalization, which the airline says has cost it $40,000 per person on average.

Unvaccinated employees will also have to wear masks indoors and be required to take a weekly COVID test beginning Sept. 12.

-ABC News' Sam Sweeney

In Illinois, masks will be required indoors regardless of vaccination status beginning on Monday, Gov. JB Pritzker announced Thursday.

The governor also said that vaccines will be required for higher education personnel and students, health care workers and P-12 teachers and staff. The unvaccinated must get tested at least once per week.

"This is a pandemic of the unvaccinated," the governor said, adding that 95% of deaths in the state are among the unvaccinated.

Illinois is now seeing 220 patients admitted to hospitals each day, the highest since May.

Florida reported 26,203 newly confirmed cases of COVID-19 to the Centers for Disease Control and Prevention on Wednesday, setting a new record for the state's single-day case counts.

Florida's previous all-time high was 25,957 new cases recorded on Aug. 12, according to data collected by the CDC.

The seven-day moving average of new cases per day in the Sunshine State now stands at 21,604. In total, Florida has reported more than 3.1 million confirmed cases statewide and over 42,000 deaths.

Japan has suspended the use of about 1.63 million doses of Moderna's COVID-19 vaccine due to reported contamination, as the country grapples with surging infections.

Japanese drugmaker Takeda Pharmaceutical Co., which is in charge of distributing the Moderna vaccine in Japan, said in a press release Thursday that it has received reports of foreign substances in some unused vials at multiple inoculation sites. Although some doses might have been administered, Takeda said there have been no reports of safety concerns tied to the affected vials so far.

After consulting with Japan's Ministry of Health, Labor and Wealth, Takeda said it decided as a safety precaution to stop using doses from three separate lots, manufactured in the same production line as the contaminated vials. The company said it has requested Moderna to conduct an emergency investigation into the issue.

For doses from non-suspended lots, Takeda urged people to check the vials for discolouration, foreign substances or other abnormalities before continuing to use. Meanwhile, the Japanese health ministry said it will work with Takeda to supply alternative doses in an effort to minimize the impact on the country's vaccination progress.

Moderna told ABC News that it has put the 1.63 million doses on hold in Japan after being notified that some of the vials may have been contaminated. One of the three lots received "several complaints of particulate matter" in its vials, the American drugmaker said, while the two other adjacent lots were put on hold out of "an abundance of caution" and for continued assurance of quality.

According to Moderna, the manufacturing issue may have come from one of the lines used at its contract manufacturing site in Spain. The Massachusetts-based company said it is looking into the contamination reports and "proactively communicating with Japan’s health authorities and its partners as the investigation proceeds." Moderna added that it remains "committed to working transparently and expeditiously" with its Japanese distribution partner and with regulators to address any potential concerns. No safety or efficacy concerns have been identified so far, the company said.

Moderna noted that the pause in Japan does not impact doses distributed in the United States, or put the American supply at risk in any way.