As the 2020 Summer Olympics plays out in Tokyo, the host city saw a record-breaking number of newly confirmed cases of COVID-19 for the third straight day.

A new all-time high of 3,865 cases were reported on Thursday, up from 3,177 on Wednesday and double the daily count a week ago, according to data from Tokyo's metropolitan government. The Games, which were postponed for a year due to the coronavirus pandemic, are being held under a regional state of emergency and stringent restrictions.

Although Japan has managed to keep its COVID-19 cases and death toll lower than many other countries, its numbers have been on the rise in recent weeks with infections soaring not just in the capital city but across the nation.

"We have never experienced the expansion of the infections of this magnitude," Japanese chief cabinet secretary Katsunobu Kato told reporters Tuesday.

At least 198 confirmed cases have been associated with the Tokyo Olympics. Of those, 24 were reported on Thursday and include three athletes who are staying at the Olympic Village, according to data from the Tokyo 2020 organizing committee.

At least 75 confirmed cases of COVID-19 across 17 U.S. states have been linked to a Christian summer camp in North Carolina, officials said.

The outbreak is associated with campers and staff who attended The Wilds camp near Rosman in North Carolina's Transylvania County between June 28 and July 17, according to a statement from the local public health department.

The camp, nestled on 1,000 acres in the Blue Ridge Mountains, offers sessions for children, adults and families.

Last week, a spokesperson for the camp told Ashevile ABC affiliate WLOS that they had cancelled sessions that week to work on enhancing COVID-19 protocols. Although there was no plan to cancel further sessions, the spokesperson said the camp was working to limit the number of attendees and started asking campers to get tested for COVID-19 before their sessions.

"We've been checking our staff, we've been doing screenings for everyone who comes onto the campsite and anticipating they're coming to our campsite healthy," the spokesperson told WLOS during a telephone interview last week. "And the anticipation is that they would leave healthy as well."

The U.S. Food and Drug Administration has approved another extension to the shelf life of Johnson & Johnson's single-shot COVID-19 vaccine, from four-and-a-half months to six months, according to J&J.

"The decision is based on data from ongoing stability assessment studies, which have demonstrated the vaccine is stable at six months when refrigerated at temperatures of 36 – 46 degrees Fahrenheit," the company said in a statement late Wednesday.

On Tuesday, the Centers for Disease Control and Prevention quietly updated its guidance on testing for vaccinated people on its website.

While the CDC had previously said vaccinated people did not have to get tested for COVID-19 after being exposed to someone with the virus, unless they had symptoms, that is no longer the case.

The government agency now recommends: "If you’ve been around someone who has COVID-19, you should get tested 3-5 days after your exposure, even if you don’t have symptoms."

"You should also wear a mask indoors in public for 14 days following exposure or until your test result is negative. You should isolate for 10 days if your test result is positive," the updated guidance states.

The nation's top infectious disease expert is warning that "things will get worse" in the pandemic as the rate of COVID-19 cases continues to surge.

Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, said during an interview on “This Week” that while he does not believe the pandemic is worsening to the point where lockdowns will be necessary again, "We are seeing an outbreak of the unvaccinated," based on the seven-day average, which "has gone up substantially."

"From the standpoint of illness, hospitalization, suffering and death, the unvaccinated are much more vulnerable because the vaccinated are protected from severe illness, for the most part, but when you look at the country as a whole. And getting us back to normal, the unvaccinated, by not being vaccinated, are allowing the propagation and the spread of the outbreak which ultimately impacts everybody," Fauci said.

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-ABC News’ Molly Nagle