A Flu Vaccine is the Best Protection Against Flu
The best way to protect against flu and its potentially serious complications is with a CDC recommends that everyone 6 months of age and older get a seasonal flu vaccine each year by the end of October. However, as long as flu viruses are circulating, vaccination should continue throughout flu season, even in January or later.
Flu vaccination is especially important for people 65 years and older because they are at high risk  of developing serious complications from flu. Flu vaccines are updated each season as needed to keep up with changing viruses. Also, immunity wanes over a year so annual vaccination is needed to ensure the best possible protection against influenza. A flu vaccine protects against the flu viruses that research indicates will be most common during the upcoming season. (See Vaccine Virus Selection  for this season’s exact vaccine composition.) The 2018-2019 flu vaccine has been updated from last season’s vaccine to better match circulating viruses. Immunity from vaccination sets in after about two weeks
Older people with weaker immune systems often have a lower protective immune response after flu vaccination compared to younger, healthier people. This can make them more susceptible to the flu. Although immune responses may be lower in the elderly, vaccine effectiveness has been similar in most flu seasons among older adults and those with chronic health conditions compared to younger, healthy adults. Despite the fact that older adults have weaker immune responses to vaccine flu vaccines, there are many reasons why people in that age group should be vaccinated each year.seniors-vaccination-factsheet-final