The Pennsylvania Department of Health is reporting a significant rise in influenza activity across the state since Thanksgiving.
Officials said Tuesday that at least half of the state's regions are experiencing outbreaks of influenza or increases in influenza-like illness, widespread activity that is not usually seen until January.
Acting Secretary of Health Michael Wolf said the number of cases reported to the department more than doubled in the past week.
"If you decided to wait, now is the perfect time to get vaccinated against the flu," Wolf said. "Ensuring that you and your family get vaccinated will reduce the chance that your holiday plans will be affected from the flu."
The Department of Health recommends the flu vaccine for everyone over the age of 6 months, but said the vaccine is especially important for the elderly, pregnant women, and people with chronic health conditions that place them at increased risk of complications from the flu.