Protection against influenza would minimize the disruption of routine activities during epidemics. Children younger than 9 years of age who have never been vaccinated for influenza before should be given a second dose 4 weeks after the first. Intramuscular administration is preferred for all age groups. The vaccines currently available are not very effective for infants under 6 months of age, and vaccination is therefore not recommended for this age group. Influenza vaccines are safe and associated with only minimal side effects.
Allergic responses are rare.
Vaccine should not be given to people who have had an anaphylactic reaction to a previous vaccine or who have shown anaphylactic hypersensitivity to eggs. Vaccination should be postponed for those with an acute febrile illness. Pregnant women may be given the vaccine at any stage of pregnancy, and for those in the high-risk groups vaccination is recommended. Improved global surveillance activities for influenza have resulted in vaccine strains that are closely matched with circulating strains. Because the advice of a health care provider is often an important factor in a person's decision to undergo vaccination, physicians should remember that autumn visits by patients in high-risk groups provide an opportunity to offer the vaccine and address any concerns about its effectiveness and side effects.