HARRISBURG, Pa. — A report from the Pennsylvania Department of Health shows more vaccinated Pennsylvanians are becoming infected with COVID-19 and ending up in hospitals.
More than one out of every four new cases over the last month in the commonwealth were in vaccinated individuals.
It's the same for hospitalizations, as hospital beds filled with more than 1,200 fully vaccinated residents.
Experts say one explanation for this is that data shows immunity from Pfizer's COVID-19 vaccine starts to wear off after about six months.
"As more and more people get farther and farther out from their last dose, then they have less immunity, which means the virus has more opportunity to move around," said Dr. Todd Husty, Seminole County, Florida's medical director.
The Department of Health officials say vaccines are still most effective at preventing hospitalizations and death.
The state's Acting Surgeon General Dr. Denise Johnson expected an increase, saying the more people getting vaccinated, the more potential for breakthrough cases.
Those who received their shots earliest may be accounting for the new cases.
Booster shots for the Pfizer vaccine are only available to adults over 65 or people who are immunocompromised.
The CDC is expected to make a decision on booster shots for Moderna and Johnson & Johnson vaccines later this month.
"While there are more breakthrough cases being recorded, Department of Health numbers show since the start of this year more than 90% of cases, hospitalizations and deaths have been in people who were unvaccinated or not fully vaccinated," added Dr. Husty.
Get county-specific coronavirus information by visiting Pennsylvania's Early Warning Monitoring System Dashboard.
View the CDC COVID data tracker here.