Menino said healthcare centers across the city would offer free vaccines to anyone who hasn't yet been immunized for flu. A list is available at the city's website http://www.cityofboston.gov/.
The Massachusetts Department of Public Health said there have been 18 flu-related deaths this season -- a flu season that came about five weeks earlier than usual.
"We're off to an early start nationally and in Massachusetts," Kevin Cranston, director of the department's Bureau of Infectious Disease, told reporters.
He said 91 percent of the viruses found in laboratory testing this year were well-matched to the seasonal flu vaccine and suggested people who have not yet been vaccinated to get a flu shot, although it takes two weeks for it to be effective.
The flu season this year is considered moderately severe, more severe than average, but not unprecedented in severity, The Boston Globe reported.
Hospitals and other healthcare facilities in Boston and Massachusetts were taking infectious diseases procedures to limit the spread of flu -- precautions not taken since the 2009 H1N1 "swine flu" pandemic -- such as prohibiting visits from children age 16 and younger. Children catch the flu more frequently at school and then spread it throughout the family and community.
Cranston said healthcare providers and hospitals have had to treat a significant number of cases of norovirus, an intestinal illness not related to influenza.