PHILADELPHIA (CBS) — COVID-19 cases in Pennsylvania are up 88% since last week. Even though the state and the City of Philadelphia have pretty good vaccination rates, cases keep climbing.

At this point, the biggest concerns are for those who are not vaccinated, which includes members of the Philadelphia Phillies. Health officials say there are also worries about breakthrough cases and summer travel.

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“It is concerning watching what’s happening around the country,” Acting Philadelphia Health Commissioner Dr. Cheryl Bettigole said. “Philadelphia is not an island. We have people coming and going from all sorts of places and they can bring COVID with them.”

The acting Philadelphia health commissioner says the increase in COVID-19 cases in the city is mainly from the Delta variant and among people who aren’t vaccinated.

“We’re seeing more cases among our young adults so ages 20-34,” Bettigole said, “So I think people may be, you know, being out and about a bit more, especially inside in a crowd.”

Philadelphia also has a growing number of breakthrough cases. Of the 750,000 people who are fully vaccinated, 739 contracted the virus anyway. That represents just over 1% of all cases. Sixty-six were hospitalized and 12 people died.

“I’m much more concerned among the number of cases we will still see in people who are not fully vaccinated,” Bettigole said. “The thing to know though about those breakthrough cases is the vast majority of them are very mild.”

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Bettigole also offered some encouragement to the Phillies players who aren’t vaccinated, including Alec Bohm.

“I would love to see them get vaccinated,” Bettigole said. “I would love to meet with them if they’re interested.”

About half of the 26 players are reportedly refusing to be vaccinated. Doctors say the virus can easily spread inside a clubhouse among teammates.

“Baseball, fortunately, is played outside,” Bettigole said, “So I wouldn’t imagine that Philly fans are at risk, but I encourage anyone who is unvaccinated to look at the data. I don’t want to pick on any one person here.”

CBS3 reached out to the Phillies for comment but has not heard back.

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Also, health officials say there is not a need for renewed restrictions at this point because hospital COVID cases have not increased.

Stephanie Stahl