By Stephanie Stahl

PHILADELPHIA (CBS) — The U.S. Centers for Disease Control and Prevention issued new guidance on wearing masks indoors on Tuesday as COVID-19 cases surge nationwide. This affects everyone, including the fully vaccinated.

The CDC issued the new recommendation because COVID is surging in some parts of the country, and there’s the ongoing issue with people who are not vaccinated and new concerns about the Delta variant.

READ MORE: Man Shot At Least 8 Times In Strawberry Mansion Left In Critical Condition, Police Say

The new guidance says vaccinated people should wear masks inside public locations, including schools, and especially in places where COVID-19 is surging. Federal health officials say there is new science on the Delta variant.

“In rare occasions, some vaccinated people infected with the Delta variants after vaccination may be contagious and spread the virus to others,” CDC Director Dr. Rochelle Walensky said. “This new science is worrisome and unfortunately warrants an update to our recommendation.”

The new CDC mask guidance comes two months after it said they were no longer needed inside for vaccinated people, but that was before the highly contagious Delta variant skyrocketed.

The U.S. is now averaging more than 50,000 new cases per day, up more than 60% over the last week’s seven-day average.

“We’re certainly worried looking at what’s happening around the country,” Philadelphia Acting Health Commissioner Dr. Cheryl Bettigole said.

Last week, the acting Philadelphia health commissioner recommended that everyone mask up inside public locations in the city because COVID cases are increasing here.

READ MORE: Delaware Gov. John Carney Requests Disaster Declaration From President Joe Biden Due Damaged Caused By Ida

“The largest increase in cases is in adults 20 to 34,” Bettigole said.

The new CDC mask recommendation for vaccinated people is mainly aimed at other parts of the country with high COVID-19 transmission rates. That’s 100 or more cases per 100,000 people or at least a 10% positivity rate in the past seven days.

But that’s not happening in the tri-state region, where the percent positivity is below 4% in Pennsylvania, New Jersey and Delaware so the new CDC mask recommendation probably wouldn’t apply here.

“You have to take into account the reality of what your state looks like,” New Jersey Gov. Phil Murphy said. “A national recommendation may or may not be consistent with the facts on the ground.”

Murphy on Monday indicated that New Jersey wouldn’t be changing its masking recommendations because while cases are going up in the Garden State, they’re nowhere near the explosion of cases happening in the south, areas targeted in the new CDC recommendation, where cases are high because vaccinations are low.

“Vaccinated people, stop thinking we’re fully protected,” Dr. Leana Wen, a former health commissioner for Baltimore, said. “We’re very well protected, but as long as there are people around us who are continuing to spread COVID-19, that’s actually making us less safe.”

MORE NEWS: Montgomery County Department Of Public Safety Is Hiring

Also on Tuesday, the CDC recommended universal indoor masking for all teachers, staff, students and visitors to schools, regardless of vaccinated status and that children return to full-time in-person learning in the fall.

Stephanie Stahl