CDC supports and emphasizes the use of influenza vaccination for reducing
influenza infections and their associated complications. CDC does not recommend
influenza vaccination for the primary purpose of reducing the number of persons
who might be evaluated for severe acute respiratory syndrome (SARS).
Influenza vaccine is effective only against influenza virus infection
and is the best option for preventing influenza and its complications. These
complications occur most often in children aged <24 months, persons aged
≥65 years, and those of any age who have certain medical conditions placing
them at high-risk for having complications from influenza infection.* Annual
vaccination is recommended for persons at high risk aged ≥6 months and
for persons in other target groups, including family members and other close
contacts of high-risk persons, those aged 50-64 years, and health-care workers.
Vaccination is encouraged, when feasible, for children aged 6-23 months and
for their household contacts and out-of-home caregivers. Influenza vaccination
of health-care workers is especially important for reducing transmission of
influenza viruses to patients with high-risk conditions in hospital and other
health-care settings and for protecting the health-care workforce during the
influenza season. Additional information about prevention and control of influenza
is available at http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5208a1.htm.
On a population level, widespread use of the influenza vaccine will
reduce the number of influenza cases and might decrease the number of persons
with a febrile respiratory illness who are evaluated for SARS. However, such
secondary benefits cannot be reliably anticipated. For example, the overall
decrease in febrile respiratory illnesses would be minimal if circulating
levels of influenza viruses are low or if other respiratory pathogens are
actively circulating in a community.
Persons vaccinated against influenza can still have a febrile respiratory
illness because influenza vaccine will not prevent infection by noninfluenza
agents and the effectiveness of influenza vaccine is <100%. Therefore,
receipt of influenza vaccination in a person who subsequently experiences
a febrile respiratory illness does not eliminate influenza as a possible cause
nor necessarily increase the likelihood that the illness is SARS.
*Persons at high risk include residents of chronic care facilities,
persons with chronic pulmonary or cardiovascular disorders (e.g., asthma,
chronic metabolic diseases, renal dysfunction, hemoglobinopathies, or immunosuppression),
children receiving long-term aspirin therapy, and women who will be in the
second or third trimester of pregnancy during the influenza season.
International Conference on Women and Infectious Diseases. JAMA. 2003;290(22):2934. doi:10.1001/jama.290.22.2934-a