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Am Fam Physician. 2008;78(8):996-999

See related editorial on page 923.

Guideline source: Centers for Disease Control and Prevention, Advisory Committee on Immunization Practices

Literature search described? No

Evidence rating system used? No

Published source:MMWR Recommendations and Reports, August 8, 2008

In the United States, annual epidemics of influenza occur typically during the late fall through early spring. Rates of infection are highest among children, and rates of serious illness and death are highest among persons 65 years and older, children younger than two years, and persons with medical conditions that put them at increased risk of complications from influenza. The Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention (CDC) has released updated recommendations for influenza control for the 2008–09 season.

Recommendations

The primary updates to this year's recommendations include the following:

  • Beginning this year, all children five to 18 years of age should be vaccinated annually. Vaccination should begin as soon as vaccine is available for the 2008–09 influenza season, but no later than during the 2009–10 season.

  • Annual vaccination of all children six months to four years of age should remain a focus of vaccination efforts because this group is at higher risk of complications.

  • Either trivalent inactivated influenza vaccine (TIV) or live, attenuated influenza vaccine (LAIV) should be used when vaccinating healthy persons two to 49 years of age (the previous recommendation was to administer LAIV to persons five to 49 years of age). Tables 1 and 2 list the available vaccines for the 2008–09 season and compare LAIV and TIV.

  • Vaccines containing the trivalent vaccine virus strains A/Brisbane/59/2007 (H1N1)-like, A/Brisbane/10/2007 (H3N2)-like, and B/Florida/4/2006-like antigens should be used during the 2008–09 influenza season.

Healthy, nonpregnant persons two to 49 years of age can choose to receive TIV or LAIV. Some TIV formulations are licensed for use in children as young as six months; TIV also is licensed for use in persons with high-risk conditions. LAIV is licensed for use only in persons two to 49 years of age, and the safety of LAIV has not been established in persons with certain medical conditions. All children six months to eight years of age who have not previously been vaccinated with at least one dose of LAIV or TIV should receive two doses of vaccine in the same season, with a single dose during subsequent seasons.

Influenza vaccine should be provided to all persons who want to reduce their risk of infection or of transmitting influenza to others. However, an emphasis should be placed on vaccinating patients at higher risk of influenza infection or complications, including children six months to 18 years of age, persons 50 years and older, and other adults at risk of medical complications from influenza or more likely to require medical care (Table 3). Persons who live with or care for persons at high risk of influenza-related complications, including health care professionals and caregivers for children younger than six months, should receive influenza vaccine annually.

Antiviral Agents

Four influenza antiviral agents are licensed in the United States: amantadine (Symmetrel), rimantadine (Flumadine), zanamivir (Relenza), and oseltamivir (Tamiflu). Oseltamivir-resistant influenza A (H1N1) strains have been identified in the United States and some other countries. However, oseltamivir and zanamivir continue to be the recommended agents for treatment of influenza because other virus strains remain sensitive to zanamivir, and resistance levels to other antiviral agents remain high.

Oseltamivir is licensed for treatment and chemoprophylaxis of influenza in persons one year and older, and zanamivir is licensed for treatment of influenza in persons seven years and older and for chemoprophylaxis in persons five years and older (for complete dosing information, see the CDC recommendations at http://cdc.gov/mmwr/preview/mmwrhtml/rr5707a1.htm). Antiviral treatment should be initiated within two days of illness onset; benefits are greater if treatment is started earlier. Although chemoprophylaxis is not a substitute for vaccination, it is a critical adjunct in preventing and controlling influenza. To be maximally effective as chemoprophylaxis, the drug must be taken each day for the duration of influenza activity in the community.

VaccineBrand nameManufacturerPresentationMercury content (mcg Hg per 0.5-mL dose)Approved agesNumber of doses requiredRoute of administration
TIV*FluzoneSanofi Pasteur0.25-mL prefilled syringe06 to 35 months1 or 2†IM‡
0.5-mL prefilled syringe0≥ 36 months1 or 2†IM‡
0.5-mL vial0≥ 36 months1 or 2†IM‡
5.0-mL multidose vial25≥ 6 months1 or 2†IM‡
TIV*FluvirinNovartis Vaccines5.0-mL multidose vial24.5≥ 4 years1 or 2†IM‡
0.5-mL prefilled syringe< 1.0≥ 4 years1 or 2†IM‡
TIV*FluarixGlaxoSmithKline0.5-mL prefilled syringe< 1.0≥ 18 years1IM‡
TIV*FlulavalGlaxoSmithKline5.0-mL multidose vial25≥ 18 years1IM‡
TIV*AfluriaCSL Biotherapies0.5-mL prefilled syringe0≥ 18 years1IM‡
5.0-mL multidose vial25≥ 18 years1IM‡
LAIV§Flumist‖Medimmune0.2-mL sprayer02 to 49 years1 or 2¶Intranasal
FactorLAIVTIV
Route of administrationIntranasal sprayIntramuscular injection
Number of included virus strains3 (2 influenza A, 1 influenza B)3 (2 influenza A, 1 influenza B)
Frequency of updates to vaccine virus strainsAnnuallyAnnually
Frequency of administrationAnnually*Annually*
Approved ages2 to 49 years †6 months and older
Interval between doses for children 6 months to 8 years of age who are receiving vaccine for the first time4 weeks4 weeks
Can be administered to persons at risk of influenza-related complications†NoYes
Can be administered to children with asthma or children 2 to 4 years of age with a history of wheezing during the preceding year‡NoYes
Can be administered to close contacts of immunosuppressed persons who do not require a protective environmentYesYes
Can be administered to close contacts of immunosuppressed persons who require a protective environment (e.g., hematopoietic stem cell transplant recipients)NoYes
Can be administered to close contacts of persons at high risk, but who are not severely immunosuppressedYesYes
Can be simultaneously administered with other vaccinesYes§Yes‖
If not simultaneously administered, can be administered within 4 weeks of another live vaccinePrudent to space 4 weeks apartYes
If not simultaneously administered, can be administered within 4 weeks of an inactivated vaccineYesYes

Data are limited about the effectiveness of zanamivir and oseltamivir in preventing serious influenza-related complications (e.g., bacterial or viral pneumonia, exacerbation of chronic disease), or for preventing influenza in persons at high risk of serious complications from the disease.

Children and adolescents
Children six months to four years of age
Children who are receiving long-term aspirin therapy (increases the risk of Reye syndrome after influenza infection)
Adults
Adults 50 years and older
Health care professionals
Any age
Household contacts and caregivers for persons with medical conditions that put them at higher risk of complications from influenza
Household contacts and caregivers for children younger than five years (especially for those younger than six months), and for adults 50 years and older
Persons with any condition that may compromise respiratory function or increase the risk of aspiration (e.g., cognitive dysfunction, spinal cord injuries, seizure disorders)
Persons with chronic pulmonary disorders (including asthma), or renal, hepatic, hematologic, or metabolic disorders (including diabetes mellitus)
Persons with immunosuppression (including immunosuppression caused by medications or human immunodeficiency virus)
Residents of nursing homes or chronic-care Facilities
Persons who are pregnant during influenza season

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