Updated Influenza Vaccine Recommendations Issued

Megan Brooks

August 18, 2011

August 18, 2011 — 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 Advisory Committee on Immunization Practices 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 μg vs 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 Advisory Committee on Immunization Practices 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 Advisory Committee on Immunization Practices 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, 2001. Full text

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