PHILADELPHIA (CBS) — Summer fun is in full swing with people traveling, enjoying get togethers and most people aren’t wearing masks. The CDC says this has ushered in a new wave of COVID cases.

“If you look at the state of NJ you see an uptick really on coastal communities,” Dr. Eric Sztejman said.

Dr. Sztejman is a pulmonologist at Virtua Health in Voorhees.

“The virus continues to mutate and we’re seeing different strains of the virus,” Dr. Sztejman said.

COVID hospitalizations over the past week are up 12% nationwide according to the latest numbers from the CDC.

In New Jersey, there’s been a 28% increase. While hospitalizations in Delaware are down 27%, there’s been no change in Pennsylvania.

Doctors say contagious infections like COVID usually go down in the summertime with more people outside, but not this summer.

“When it gets really hot, people go indoors, when it gets really cold, people go indoors, and when you’re inside the ventilation is different, people are closer together. So I think that’s part of it,” Dr. David Wohl, an infectious disease physician, said.

But experts say this surge is far less intense than in past years. Even with a 30 to 40% increase in cases since June, the numbers are still considered low compared to some previous spikes.

“Although the virus doesn’t seem very strong right now I anticipate with mutations we could see a re-accumulation of cases in the fall,” Dr. Sztejman said. 

Long COVID patients are remaining wary of potential upticks with the virus.

“We still have this disease out there so it is scary,” Joy Ezekiel-Gibson said.

Ezekiel-Gibson had an early serious case of COVID that caused organ damage.

“I hope people take it seriously,” Ezekiel-Gibson said. “I’ve given up trying to prove to people it’s real.”

Ezekiel-Gibson was on a ventilator for 17 days.

The South Jersey local had a bad case of Long COVID, which caused brain fog and fatigue. Even though the virus isn’t as dangerous now, she’s worried about the summer resurgence.

Dr. Sztejman says because of the heat more people are inside this summer so that’s also contributing to the spike in cases.

Doctors say 25% of people who get Covid go on to develop Long COVID and they don’t know why. It can happen to anyone.

“There’s no rhyme or reason that we identified what can cause Long COVID,” Dr. Sztejman said.

This new summer surge might also be related to vaccine effectiveness wearing off as the virus has continued to mutate.

“Most of us haven’t received our vaccines for quite some time so some of the immunity we received from the vaccine may have fallen off,” Dr. Sztejman said.

Boosters currently available are recommended for high-risk groups and for people who will be traveling. An updated version of the booster is expected in late September.

The updated vaccine is aiming to cover the new COVID mutations that are spreading now and are expected to increase through the winter season. 

There’s no word yet from the CDC on what the recommendation will be for who should get the updated version.