PPA Article
Updated Recommendations for Influenza Vaccine Released CME/CE
News Author: Megan Brooks
CME Author: Charles P. Vega, MD
CME/CE Released: 08/26/2011; Valid for credit through 08/26/2012
Clinical Context
Influenza remains one of the gravest threats to public health, and an article in the June 3, 2011, issue of Morbidity and Mortality Weekly Report summarized the severity of the 2010-2011 influenza season. The incidence of clinician visits for influenza-like illness peaked at 4.6% of the population in February 2011. This figure was roughly similar to previous years, and the infection trend with influenza began in the southeastern United States. Unlike recent years, the rate of hospitalization from influenza was higher among older adults and lower among children.
The most effective means to prevent infection with influenza is the influenza vaccine. The current recommendations of the Advisory Committee on Immunization Practices (ACIP) describe the best practice for the application of the vaccine in 2011.
Study Synopsis and Perspective
Updated guidance for influenza vaccination in the United States for the upcoming 2011-2012 influenza season has been released by federal health officials with the Centers for Disease Control and Prevention (CDC).
"There are relatively few changes from 2010-2011 recommendations," Carolyn Bridges, MD, associate director for adult immunization, Immunization Services Division, National Center for Immunization and Respiratory Disease, said during a telebriefing today.
As a result, the 2011-2012 recommendations from the ACIP have been issued in a shortened format, Dr. Bridges noted.
The report was published online August 18 in the Morbidity and Mortality Weekly Report.
The 2010 recommendation for routine annual influenza vaccination for all persons aged 6 months or older in the United States has not changed.
"We continue to recommend that people age 6 months and older be vaccinated," Dr. Bridges emphasized.
To allow time for production of protective antibody levels, "vaccination should optimally occur before onset of influenza activity in the community, and providers should offer vaccination as soon as vaccine is available," the report reads. "Vaccination also should continue to be offered throughout the influenza season."
Vaccine Strains Identical to Last Year
This year's seasonal influenza vaccine virus strains are identical to those contained in last year's vaccine. These include A/California/7/2009 (H1N1)-like, A/Perth/16/2009 (H3N2)-like, and B/Brisbane/60/2008-like antigens. The influenza A (H1N1) vaccine virus strain is derived from a 2009 pandemic influenza A (H1N1) virus.
Dr. Bridges emphasized that the recommendation for annual vaccination remains in place, even though the strains of this year's vaccine are the same as those in 2010-2011.
"Levels of protective antibody against influenza viruses can decline over the course of a year, so even people who got a flu vaccine last year should get vaccinated again this year to ensure that they are optimally protected," she said.
The report reminds providers that children aged 6 months through 8 years need 2 doses of influenza vaccine, administered a minimum of 4 weeks apart, during their first season of vaccination to optimize immune response.
In past influenza seasons, children aged 6 months through 8 years who received only 1 dose of influenza vaccine in their first year of vaccination required 2 doses the following season. However, because the 2011-2012 vaccine strains are unchanged from the 2010-2011 vaccine strains, "children in this age group who received at least 1 dose of the 2010-2011 seasonal vaccine will require only 1 dose of the 2011-2012 vaccine," the report states.
"Children in this age group who did not receive at least 1 dose of the 2010-2011 seasonal influenza vaccine, or for whom it is not certain whether the 2010-2011 seasonal vaccine was received, should receive 2 doses of the 2011-2012 seasonal influenza vaccine," it adds.
Multiple Products to Be Available
Multiple influenza vaccines are expected to be available during the upcoming influenza season, all containing the same antigenic composition, the CDC notes.
"We are anticipating, based on reports from manufacturers, that probably 166 million or so doses of vaccine will be produced this year; that compares with 157 million doses that were distributed last year," Dr. Bridges said.
The updated recommendations make note of the new intradermally administered trivalent inactivated vaccine (TIV) preparation (Fluzone Intradermal, Sanofi Pasteur) licensed in May 2011.
This vaccine is indicated for people 18 to 64 years old and contains less antigen than intramuscular TIV preparations (9 μgvs 15 μg of each strain per dose) in a smaller volume (0.1 mL vs 0.5 mL).
This vaccine is administered in a single dose (preferably over the deltoid muscle) and comes in a prefilled microinjection syringe. The most common adverse reactions include injection-site erythema, induration, swelling, pain, and pruritus, the CDC notes. With the exception of pain, these reactions occurred more frequently than with intramuscular vaccine, but generally resolved within 3 to 7 days.
"This vaccine is an alternative to other TIV preparations for those in the indicated age range, with no preferential recommendation," the agency writes.
Recommendations for People With Egg Allergy
When considering influenza vaccination in people who have or report a history of egg allergy, several considerations must be taken into account, the ACIP notes. For those who have experienced only hives after exposure to egg, it is recommended that the inactivated vaccine, rather than live attenuated vaccine, be used.
For these individuals, it is also recommended that vaccine be administered by a healthcare provider familiar with the potential manifestations of egg allergy, and that vaccine recipients be observed for at least 30 minutes after receipt of the vaccine.
"Other measures, such as dividing and administering the vaccine by a two-step approach and skin testing with vaccine, are not necessary," the report states.
The report also states that persons who have had reactions to egg involving angioedema, respiratory distress, lightheadedness, or recurrent emesis, or those who required epinephrine or other emergency medical intervention, are more likely to have a serious systemic or anaphylactic reaction on reexposure to egg proteins. "Before receipt of vaccine, such persons should be referred to a physician with expertise in the management of allergic conditions for further risk assessment," the ACIP recommends.
"A previous severe allergic reaction to influenza vaccine, regardless of the component suspected to be responsible for the reaction, is a contraindication to receipt of influenza vaccine," the report states.
Vaccination Rates Still Low in Providers, Pregnant Women
During the telebriefing, Dr. Bridges reported data on vaccination rates in 2 key groups: healthcare providers and pregnant women. She said that although vaccination rates have risen in healthcare providers, they still remain "far too low."
During the 2010-2011 season, estimated coverage rates among healthcare personnel were 63.5%, which is "well below the Healthy People 2020 goal of 90%," Dr. Bridges noted. The 63.5% coverage rate for the 2010-2011 season is up from the 62% coverage rate in the prior season (2009-2010), she noted.
It is currently recommended that all healthcare personnel be vaccinated annually. This is "important for patient safety, and healthcare facilities should make influenza vaccine readily available to all healthcare personnel as part of a comprehensive infection control program," Dr. Bridges said.
Influenza vaccine coverage rates among pregnant women also remain low, according to Dr. Bridges, with only about half of pregnant women in the United States getting vaccinated during the 2009-2010 and 2010-2011 seasons.
"Pregnant women and children younger than 6 months of age are known to be at higher risk for severe illness from influenza," Dr. Bridges noted. "Vaccination during pregnancy has been shown to decrease the risk [for] illness in the mother, as well as the risk of influenza and influenza hospitalization in their infants during the first 6 months of life."
"Continued efforts are needed to encourage providers to strongly recommend and offer vaccination to their pregnant patients," Dr. Bridges said.
Morb Mortal Wkly Rep. Published online August 18, 2011.Full text
Study Highlights
- The ACIP Influenza Work Group meets every 2 to 4 weeks throughout the year and developed the current vaccination recommendations through these meetings.
- The recommendation that all persons at least 6 months old should receive vaccination remains the same as in 2010.
- The components of the influenza vaccine remain the same as 2010, with 2 strains of influenza A (including one H1N1-like strain) and 1 strain of influenza B.
- Children between the ages of 6 months and 8 years require 2 doses of influenza vaccine, at least 1 month apart, during their first vaccination season. Subsequently, they may receive 1 dose annually.
- The similarity of antigenic components appears more important than the temporal interval between doses of influenza vaccine. Because the antigenic components of the vaccine are the same in 2011 as in 2010, children at ages 6 months through 8 years who received only 1 dose of the vaccine last year may receive 1 dose of the vaccine again this year.
- Multiple vaccine delivery systems exist, but they all have the same antigenic composition.
- The TIV should be applied intramuscularly. The deltoid is the preferred site of injection among adults and older children, whereas infants and younger children may receive the injection in the anterolateral aspect of the thigh.
- A new intradermal TIV was approved in May 2011. This vaccine is indicated for adults between 18 and 64 years old and has a lower antigenic load vs the intramuscular vaccine. The intradermal vaccine is associated with higher rates of injection-site erythema, induration, swelling, and pruritus vs with the intramuscular vaccine.
- A high-dose influenza vaccine is also available for adults at 65 years or older, but this vaccine is not recommended vs the standard TIV.
- The intranasal influenza vaccine remains an option for healthy persons between the ages of 2 and 49 years.
- Egg allergy is considered a contraindication to vaccination against influenza, because all vaccine preparations begin with the virus being injected into eggs. However, the risk for clinical consequences associated with influenza vaccination among individuals with egg allergy has generally been overstated.
- Patients who have experienced only hives after being exposed to eggs should receive the influenza vaccine if emergency care is available and the patient is observed for at least 30 minutes after vaccination.
- However, patients who have had a more severe reaction to eggs should see an allergy specialist before receiving the influenza vaccination.
- Other measures, such as skin testing with the vaccine or dividing the standard dose into 2 equal injections, are not necessary.
Clinical Implications
- Higher numbers of clinician visits for influenza-like illness during the 2010-2011 influenza season began in the southeastern United States and peaked in February. More older adults and fewer children were hospitalized for influenza during the last influenza season vs recent years.
- Because the antigenic components of the influenza vaccine are the same as those of 2010, children who received only 1 dose of their initial influenza vaccine last year may receive 1 dose only this year.