WITH FLU SEASON starting, no doubt you're already seeing patients complaining of fever, malaise, headache, myalgia, nonproductive cough, pharyngitis, and rhinitis. Young patients may also present with otitis media, nausea, and vomiting. Most cases of seasonal flu spontaneously resolve within 3 to 7 days; however, the very young, older adults, and those who are immunocompromised may experience an exacerbation of other medical conditions and be at risk for developing sinusitis, otitis media, pneumonia, and fatal complications.
Influenza season typically occurs between late fall and early spring. Most people are susceptible to the flu, and the highest rates of infection and death generally occur in those who are immunocompromised, children under age 2, and those over age 65. Novel H1N1, previously known as swine flu, is different than seasonal influenza: adults over age 64 don't appear to be at increased risk for novel H1N1-related complications so far.1
The most effective way to protect you and your patients from influenza virus is to practice good hand hygiene and get an annual influenza vaccination. At press time, a vaccine against the novel H1N1 virus was expected to be available by mid-October (see What about novel H1N1?)
Designing an effective vaccine
Each year, the FDA, under the recommendations of the Vaccines and Related Biological Products Advisory Committee, selects three virus strains to target in the annual influenza vaccine. The three strains selected for the 2009–2010 flu season are A/Brisbane/59/2007 (H1N1)-like virus, A/Brisbane/10/2007 (H3N2)-like virus, and B/Brisbane/60/2008-like virus.
These influenza strains are selected after experts from the FDA, CDC, and the World Health Organization (WHO) collect and study strains of influenza from around the world and identify those most likely to cause the most illness in the upcoming flu season.
Sometimes the viral strains selected don't actually cause the greatest illness. Experts believe, however, that even an imperfect influenza vaccine provides some protection against circulating viruses, reducing signs and symptoms and duration of illness.2
Two vaccines for seasonal flu
Every year, two seasonal influenza vaccines are produced:
* the trivalent inactivated influenza vaccine (TIV), which is made from inactivated viruses that won't cause influenza. It's given I.M. and can be given to people 6 months of age or older, including those who don't have an underlying medical condition that predisposes them to influenza complications, as well as those with high-risk conditions such as pregnant women, the immunocompromised, and older adults. Adults and older children receive the injection in the deltoid muscle; infants and young children receive the injection in the anterolateral aspect of the thigh.
* the live attenuated influenza vaccine (LAIV) intranasal spray, which is made from weakened viruses that won't cause influenza. It may be used only in healthy, nonpregnant women and healthy people between ages 2 and 49. It's provided as a single-use divided dose sprayer. With the patient in an upright seated position, place the tip just inside the nostril, then depress the plunger in a quick, single motion until the clip on the plunger stops you from going any further. Remove the attached dose-divider clip and spray the remaining vaccine in a quick, single motion into the second nostril.
Both vaccines are grown in eggs, so take an allergy history before administering either type. Tell patients who are allergic to eggs to consult their healthcare provider before receiving the vaccine; hypersensitivity may result in anaphylaxis.
Store both vaccines in a medication refrigerator between 35° and 46°F (2° and 8° C). Discard any vaccines that have been frozen or are outdated, such as a previous year's influenza vaccine.3
Current recommendations
The National Center for Immunizations and Respiratory Diseases has published the following recommendations:
* All children between ages 6 months and 19 years should receive an annual influenza vaccine.
* Begin giving influenza vaccinations in September or as soon as the vaccine is available, whichever comes first.
* In case of a vaccine shortage, children and adolescents at an increased risk for influenza complications should get first priority.
* Children under age 9 being vaccinated for the first time should receive two doses of vaccine, 4 weeks or more apart in the first year, with either LAIV or the TIV. Children under age 9 who received only one dose the first season of the vaccination year should receive 2 doses of vaccine, 4 weeks apart, during the second season.3
* Don't administer LAIV to children under age 2 or to individuals with asthma or children under age 5 with recurrent wheezing. Children with reactive airway disease, children under age 2, persons who are at high risk for influenza complications, and persons age 49 and older should receive TIV.4
WHAT ABOUT NOVEL H1N1?
The 2009–2010 annual flu vaccine won't include novel H1N1 flu virus (previously known as swine flu), the cause of the current WHO-declared flu pandemic. Instead, a separate novel H1N1 flu vaccine is being developed.
The CDC has targeted five key populations to receive the novel H1N1 vaccine first when it becomes available to help reduce the H1N1 flu's spread.
* pregnant women
* people who live with or care for children younger than age 6 months
* healthcare and emergency medical services personnel
* children and young adults between the ages of 6 months and 24 years
* anyone age 25 through 64 with chronic health conditions.5
REFERENCES
1. Centers for Disease Control and Prevention. Novel H1N1 flu (swine flu) and you. http://cdc.gov/h1n1flu/qa.htm . [Context Link]
2. Influenza virus vaccine for the 2009–2010 season. http://www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Post-MarketActivities/LotReleases/ucm162050.htm . [Context Link]
3. Centers for Disease Control and Prevention. Influenza vaccination: a summary for clinicians. http://www.cdc.gov/flu/professionals/vaccination/vax-summary.htm . [Context Link]
4. National Center for Immunizations and Respiratory Diseases 2008 Annual Report. http://www.cdc.gov/ncird/annual-rpts/ar2008/bk-ar2008-s1.pdf . [Context Link]
5. Centers for Disease Control and Prevention. Novel H1N1 vaccination recommendations. http://www.cdc.gov/h1n1flu/vaccination/acip.htm . [Context Link]
