Influenza has been detected in New York City, but city health officials say there is still time to get a flu short.

"The best way to protect yourself or your loved ones from getting very ill is to get vaccinated," Dr. Thomas R. Frieden, New York City health commissioner, said in a statement.

"Young children and older adults are at higher risk of hospitalization and death if they get sick. So don't take the risk -- get the vaccine today."

Surveillance systems indicate that influenza is now spreading among New Yorkers, the health department reported. However, there is plenty of vaccine available and there is still time to get vaccinated, Frieden said.

Influenza is a highly contagious respiratory infection that, together with pneumonia, kills thousands of New Yorkers every year. Besides safeguarding people from days or weeks of debilitating sickness, the vaccine can prevent unnecessary school absences, doctor visits and hospitalizations, officials said.