<P> Influenza vaccines , also known as flu shots or flu jabs , are vaccines that protect against infection by Influenza viruses . A new version of the vaccine is developed twice a year , as the Influenza virus rapidly changes . While their effectiveness varies from year to year , most provide modest to high protection against influenza . The CDC estimates that vaccination against influenza reduces sickness , medical visits , hospitalizations , and deaths . When an immunized worker does catch the flu , they are on average back at work a half day sooner . Vaccine effectiveness in those under two years old and over 65 years old remains unknown due to the low quality of the research . Vaccinating children may protect those around them . </P>
<P> Influenza vaccines , also known as flu shots or flu jabs , are vaccines that protect against infection by Influenza viruses . A new version of the vaccine is developed twice a year , as the Influenza virus rapidly changes . While their effectiveness varies from year to year , most provide modest to high protection against influenza . The CDC estimates that vaccination against influenza reduces sickness , medical visits , hospitalizations , and deaths . When an immunized worker does catch the flu , they are on average back at work a half day sooner . Vaccine effectiveness in those under two years old and over 65 years old remains unknown due to the low quality of the research . Vaccinating children may protect those around them . </P>
a primary reason for needing a new vaccine for influenza each year is that
a primary reason for needing a new vaccine for influenza each year is that
the Influenza virus rapidly changes
the Influenza virus rapidly changes