- CONDITION CENTERS
Dr. Thune is an assistant professor of pharmacy practice at Midwestern University College of Pharmacy, Glendale, Ariz.
With daily updates about the potential avian influenza pandemic in the mass media, it seems that standard seasonal influenza (flu) is no more serious than the common cold. The flu can be responsible for significant morbidity and mortality, however. Now that the flu season is upon us, it is important to keep abreast of practice changes and updates on the prevention and treatment of the flu. It should be a concern in all pharmacists' practices regardless of their specialty or practice site. From geriatrics to pediatrics, acute care to ambulatory care, few disease states are as omnipresent as the flu.
The 2006-2007 flu season had the lowest rate of mortality and pediatric hospitalizations in the last 3 flu seasons. The flu season peaked in February, but it remained well below epidemic thresholds. As with other flu seasons, the influenza A virus (mostly H3 and H1) was much more commonly isolated than influenza B.1
Despite the good news about last year's flu season, the rate of pediatric influenza-related deaths and coinfections with Staphylococcus aureus has increased. Sixty-eight deaths occurred from October 2006 to May 2007. During the 2004-2005 flu season, one S aureus coinfection was reported among pediatric deaths. The number rose sharply to 21 during the 2006-2007 season.
Another upsetting trend seen in pediatric patients during the 2006-2007 flu season is the apparent lack of vaccination adherence. Although vaccination status was unknown for 15 of the 68 pediatric patients who died, the remaining 53 had a vaccination rate of 6%.1
Two types of flu vaccines are currently available on the market: the live attenuated intranasal vaccine (LAIV) and the trivalent inactivated vaccine (TIV), which is typically administered intramuscularly. Viral components of both vaccines are grown in eggs, so the vaccine should be avoided in patients with egg allergies. If the vaccine is absolutely necessary, desensitization protocols can be used. The LAIV, like other live vaccines, should be avoided in immunocompromised patients.2
The Centers for Disease Control and Prevention (CDC) and the World Health Organization identify the virus isolates during each flu season, and the Vaccine and Related Biologics Advisory Committee of the FDA is charged with selecting the components of that year's flu vaccine. This year, the vaccine was modified to update the influenza A (H1N1) component to make it similar to the virus antigen often isolated in the 2006-2007 season.1
The CDC's Advisory Committee on Immunization Practices published new guidelines for the administration of the flu vaccine in June 2007. The changes focus on pediatric patients, improvement of vaccination rates, and health care personnel.2
The new guidelines stress the importance of using double vaccination in children who have not been previously vaccinated against the flu or who have received only 1 dose in the previous year. The TIV requires that the 2 doses be separated by 4 weeks, and 6 weeks' separation is necessary for LAIV. There is no preference for either type of vaccine in pediatrics; however, the LAIV is FDA-approved in children ≥5 years of age. After a child is treated with 2 flu vaccine doses in 1 year, the child may receive 1 dose annually.3
The American Academy of Pediatrics (AAP) also published guidelines in 2007 addressing the prevention of influenza. AAP recommends that any contacts with infants not old enough to be vaccinated (<6 months) should be immunized. The recommendation is also true for caregivers and contacts for all children <5 years and any children who are at high risk from influenza complications.4
Pharmacists who are vaccine providers will be encouraged by the CDC's recommendation that the flu vaccine be offered during flu-season health care visits. The guidelines also state that providers should offer vaccination clinics throughout the flu season in order to increase the vaccinated population.
Vaccination rates are lower than desired, especially for at-risk populations. Elderly patients (>65 years of age) have the highest rate of mortality during influenza epidemics.5 The 2005 vaccination rate for these patients was 59.6%.2 This number is desirable when contrasted with another at-risk group, pregnant women, whose 2005 rate was only 15.6%.2
The focus on health care personnel vaccination stems from their exposure to high-risk individuals. It is important that both patients and caregivers be vaccinated to prevent spread from one population to the other. About 33% of health care personnel were immunized against the flu in 2005. Because of this low number, the CDC recommends that health care institutions use flu-vaccination status as a quality marker for infection control. They suggest signed documents of refusal be obtained from health care personnel who choose not to be vaccinated.2
Two groups of antiviral medications have been used to combat flu symptoms and prevent exposure: the neuraminidase inhibitors (NAIs; oseltamivir and zanamivir) and the adamantanes (amantadine and rimantadine). The NAIs are newer to the market, introduced within the last decade. Amantadine has been available since the early 1980s as an anti- Parkinson's agent.
The CDC discourages using the adamantanes for treatment or prophylaxis against the flu because of increasing resistance to current influenza A strains.2 When antiviral treatment or prophylaxis is required, the NAIs are the drug of choice. It is important to note that antiviral medications should be avoided within 2 weeks of receiving the LAIV because the antivirals can decrease the effectiveness of the vaccine.6-8 The medications should be started within 48 hours of the appearance of symptoms for greatest effectiveness.7,8
Zanamivir (Relenza) is an inhaled NAI used twice daily for 5 days for treatment and 10 days for prophylaxis of the seasonal flu. It is indicated for adults and children =5 years of age. Because of its unique Diskhaler delivery system, it is important that patients receive adequate counseling to ensure proper use. Zanamivir should not be used in patients with chronic obstructive pulmonary disease, asthma, or any other underlying respiratory diseases with the potential for bronchospasm. Headache is the most common adverse effect.7
Oseltamivir (Tamiflu), the more popular NAI, is available as a 75-mg capsule and 60-mg/5-mL suspension and is indicated for the treatment and prophylaxis of seasonal flu in adults and children ≥12 months of age (see Table for dosing). Oseltamivir, compared with placebo, was also shown to decrease the occurrence of acute otitis media in children aged 1 to 12 years.9 In contrast to the inhaled zanamivir, the most common adverse effect of oseltamivir is gastrointestinal disturbances. A Dear Health Care Professional letter was issued in November 2006 concerning recent safety data monitored by the FDA. There have been a small number of cases of central nervous system disturbances resulting in self-injury and delirium after receipt of the drug. This effect is more common in pediatric patients in Japan, where consumption of oseltamivir is much higher than in the United States.8
The seasonal flu is a concern to any pharmacist who provides patient care in any type of setting. Ambulatory pharmacists can improve vaccine adherence by offering vaccination clinics and counseling patients on pharmacologic supportive care to treat symptoms as well as important nonpharmaceutical interventions that can help prevent the spread of the virus. Pharmacists in health systems practice can partner with other disciplines to improve patient safety by ensuring all health care personnel receive the flu vaccine and designing vaccination pathways to make sure all patients are discharged with proper immunizations during the flu season.