New Flu Guidelines Seek to Improve Vaccination Rates

Dr. Thune is an assistant professor ofpharmacy practice at MidwesternUniversity College of Pharmacy,Glendale, Ariz.

With daily updates about thepotential avian influenza pandemicin the mass media, itseems that standard seasonal influenza(flu) is no more serious than the commoncold. The flu can be responsible for significantmorbidity and mortality, however.Now that the flu season is upon us, it isimportant to keep abreast of practicechanges and updates on the preventionand treatment of the flu. It should be aconcern in all pharmacists' practicesregardless of their specialty or practicesite. From geriatrics to pediatrics, acutecare to ambulatory care, few diseasestates are as omnipresent as the flu.

A Look Back on the 2006-2007 Influenza Season

The 2006-2007 flu season had the lowestrate of mortality and pediatric hospitalizationsin the last 3 flu seasons. Theflu season peaked in February, but itremained well below epidemic thresholds.As with other flu seasons, theinfluenza A virus (mostly H3 and H1) wasmuch more commonly isolated thaninfluenza B.¹

Despite the good news about lastyear's flu season, the rate of pediatricinfluenza-related deaths and coinfectionswith Staphylococcus aureus hasincreased. Sixty-eight deaths occurredfrom October 2006 to May 2007. Duringthe 2004-2005 flu season, one S aureuscoinfection was reported among pediatricdeaths. The number rose sharply to21 during the 2006-2007 season.

Another upsetting trend seen in pediatricpatients during the 2006-2007 fluseason is the apparent lack of vaccinationadherence. Although vaccinationstatus was unknown for 15 of the 68pediatric patients who died, the remaining53 had a vaccination rate of 6%.¹

Vaccination Recommendations

Two types of flu vaccines are currentlyavailable on the market: the live attenuatedintranasal vaccine (LAIV) and thetrivalent inactivated vaccine (TIV), whichis typically administered intramuscularly.Viral components of both vaccines aregrown in eggs, so the vaccine should beavoided in patients with egg allergies. Ifthe vaccine is absolutely necessary,desensitization protocols can be used.The LAIV, like other live vaccines, shouldbe avoided in immunocompromisedpatients.²

The Centers for Disease Control andPrevention (CDC) and the World HealthOrganization identify the virus isolatesduring each flu season, and the Vaccineand Related Biologics AdvisoryCommittee of the FDA is charged withselecting the components of that year'sflu vaccine. This year, the vaccine wasmodified to update the influenza A(H1N1) component to make it similar tothe virus antigen often isolated in the2006-2007 season.¹

The CDC's AdvisoryCommittee on ImmunizationPractices publishednew guidelines forthe administration of theflu vaccine in June 2007.The changes focus onpediatric patients, improvementof vaccinationrates, and health carepersonnel.²

The new guidelinesstress the importance ofusing double vaccinationin children who have notbeen previously vaccinatedagainst the flu or whohave received only 1dose in the previous year.The TIV requires that the2 doses be separated by4 weeks, and 6 weeks'separation is necessaryfor LAIV. There is no preferencefor either type of vaccine in pediatrics;however, the LAIV is FDA-approvedin children ≥5 years of age. Aftera child is treated with 2 flu vaccinedoses in 1 year, the child may receive 1dose annually.³

The American Academy of Pediatrics(AAP) also published guidelines in 2007addressing the prevention of influenza.AAP recommends that any contacts withinfants not old enough to be vaccinated(<6 months) should be immunized. Therecommendation is also true for caregivers and contacts for all children <5years and any children who are at highrisk from influenza complications.⁴

Pharmacists who are vaccine providerswill be encouraged by the CDC'srecommendation that the flu vaccine beoffered during flu-season health care visits.The guidelines also state that providersshould offer vaccination clinicsthroughout the flu season in order toincrease the vaccinated population.

Vaccination rates are lower thandesired, especially for at-risk populations.Elderly patients (>65 years of age) havethe highest rate of mortality during influenzaepidemics.⁵ The 2005 vaccinationrate for these patients was 59.6%.² Thisnumber is desirable when contrastedwith another at-risk group, pregnant women,whose 2005 rate was only 15.6%.²

The focus on health care personnelvaccination stems from their exposure tohigh-risk individuals. It is important thatboth patients and caregivers be vaccinatedto prevent spread from one populationto the other. About 33% of healthcare personnel were immunized againstthe flu in 2005. Because of this low number,the CDC recommends that healthcare institutions use flu-vaccination statusas a quality marker for infection control.They suggest signed documents ofrefusal be obtained from health care personnelwho choose not to be vaccinated.²

Antiviral Treatment

Two groups of antiviral medicationshave been used to combat flu symptomsand prevent exposure: the neuraminidaseinhibitors (NAIs; oseltamivir andzanamivir) and the adamantanes (amantadineand rimantadine). The NAIs arenewer to the market, introduced withinthe last decade. Amantadine has beenavailable since the early 1980s as an anti-Parkinson's agent.

The CDC discourages using theadamantanes for treatment or prophylaxisagainst the flu because of increasingresistance to current influenza Astrains.² When antiviral treatment or prophylaxisis required, the NAIs are thedrug of choice. It is important to note thatantiviral medications should be avoidedwithin 2 weeks of receiving the LAIVbecause the antivirals can decrease theeffectiveness of the vaccine.^6-8 The medicationsshould be started within 48hours of the appearance of symptomsfor greatest effectiveness.^7,8

Zanamivir (Relenza) is an inhaled NAIused twice daily for 5 days for treatmentand 10 days for prophylaxis of the seasonalflu. It is indicated for adults andchildren =5 years of age. Because of itsunique Diskhaler delivery system, it isimportant that patients receive adequatecounseling to ensure proper use. Zanamivirshould not be used in patientswith chronic obstructive pulmonary disease,asthma, or any other underlyingrespiratory diseases with the potentialfor bronchospasm. Headache is the mostcommon adverse effect.⁷

Oseltamivir (Tamiflu), the more popularNAI, is available as a 75-mg capsule and60-mg/5-mL suspension and is indicatedfor the treatment and prophylaxis of seasonalflu in adults and children &#8805;12months of age (see Table for dosing).Oseltamivir, compared with placebo, wasalso shown to decrease the occurrenceof acute otitis media in children aged 1 to12 years.⁹ In contrast to the inhaledzanamivir, the most common adverseeffect of oseltamivir is gastrointestinaldisturbances. A Dear Health CareProfessional letter was issued inNovember 2006 concerning recent safetydata monitored by the FDA. Therehave been a small number of cases ofcentral nervous system disturbancesresulting in self-injury and delirium afterreceipt of the drug. This effect is morecommon in pediatric patients in Japan,where consumption of oseltamivir ismuch higher than in the United States.⁸

Conclusion

The seasonal flu is a concern to anypharmacist who provides patient care inany type of setting. Ambulatory pharmacistscan improve vaccine adherence byoffering vaccination clinics and counselingpatients on pharmacologic supportivecare to treat symptoms as well asimportant nonpharmaceutical interventionsthat can help prevent the spread ofthe virus. Pharmacists in health systemspractice can partner with other disciplinesto improve patient safety byensuring all health care personnelreceive the flu vaccine and designingvaccination pathways to make sure allpatients are discharged with properimmunizations during the flu season.

Table

References

• Update: Influenza Activity-United States and Worldwide, 2006-2007 Season, and Composition of the 2007-2008 Influenza Vaccine. MMWR. 2007; 56(31):789-794.
• Centers for Disease Control and Prevention. Seasonal Flu. Available at: www.cdc.gov/flu.
• Prevention and Control of Influenza. MMWR. 2007;56(RR-06):1-54.
• Committee on Infectious Diseases. Prevention of Influenza: Recommendations for Influenza Immunization of Children, 2006-2007. Pediatrics. 2007;119:846-851.
• Williams GO. Vaccines in older patients: combating the risk of mortality. Geriatrics. 1980;35:55-64.
• FluMist prescribing information. Available at: www.flumist.com/prescribing-information.aspx.
• Relenza prescribing information. Available at: us.gsk.com/products/assets/us_relenza.pdf.
• Tamiflu prescribing information. Available at: www.rocheusa.com/products/tamiflu/pi.pdf.
• Committee on Infectious Diseases. Antiviral Therapy and Prophylaxis for Influenza in Children. Pediatrics. 2007;119:852-860.