The proportion of COVID-19 infections and hospitalizations among vaccinated Pennsylvania residents rose sharply last month, though the shot remained broadly protective. The latest Department of Health data on so-called “breakthrough” infections shows that between Sept. 5 and Oct. 4, vaccinated people represented just over a quarter — 26% — of more than 135,000 new infections and nearly 5,000 hospital admissions across the state. Death statistics for the last 30 days were not available because of lags in reporting and verification.