CDC Releases Guidance for 2018-19 Influenza Season

AAFP Gives Preferential Recommendation for IIV

September 06, 2018, 03:57 pm Chris Crawford – On Aug. 24, the CDC released a Morbidity and Mortality Weekly Report (MMWR) summarizing recommendations from the Advisory Committee on Immunization Practices (ACIP) for the 2018-19 influenza season.

AAFP's Preferential Recommendation

During the previous two flu seasons (2016-17 and 2017-18), the ACIP recommended against using LAIV4 because the vaccine's influenza A (H1N1) component wasn't protecting people against that influenza strain.

After the ACIP recommended that LAIV4 be included among vaccine options for the upcoming flu season during its June 20-21 meeting, the AAFP reviewed the supporting evidence presented at that event and decided to recommend IIV formulations as preferred options to LAIV4 for nonpregnant patients ages 2-49. (Editor's Note: This preferential recommendation has since been rescinded.)

The Academy's preferential recommendation for IIV does note that LAIV4 may still be used to vaccinate nonpregnant patients ages 2-49 who would not otherwise be vaccinated.

More broadly, for the 2018-19 influenza season, the AAFP and the ACIP both recommend routine annual influenza vaccination for all patients ages six months and older who don't have contraindications.

Insight From an FP Expert

The ACIP OK'd the use of LAIV4 for the 2018-19 flu season after FluMist manufacturer MedImmune, a subsidiary of AstraZeneca, reported it had replaced the influenza A (H1N1) component it had previously used (substrain A Slovenia 2903/2015 [H1N1] -- an A/Michigan/45/2015 [H1N1]pdm09-like virus) with a more effective version of the component for the upcoming flu season.

"They found that the newer substrain replicates better and is more immunogenic in humans," said AAFP Commission on Health of the Public and Science (CHPS) member James Stevermer, M.D., of Fulton, Mo. "However, there are no population data that show that it is effective against that particular H1N1 strain."

Unfortunately, that information won't be known until an influenza A (H1N1)pdm09 strain dominates a flu season, Stevermer told AAFP News.

LAIV4 does, however, appear to be effective against other recent influenza strains such as A (H3N2) and B strains, he added.

The AAFP's CHPS decided to recommend that LAIV4 be used for instances in which patients wouldn't otherwise get vaccinated, such as for school programs, Stevermer said.

"School programs might use nasal vaccines out of convenience to avoid dealing with sharps, in which case, LAIV is better than nothing," he said. "Some children are afraid of needles, as well."

Explaining the AAFP's position on LAIV4, which Stevermer noted is similar to that of the American Academy of Pediatrics, he said: "We were concerned about the lack of evidence of actual effectiveness, but also acknowledge the pragmatic issues. Where possible, family physicians should use the IIV or RIV vaccines. But we realize there will be logistic or patient-related issues that make the LAIV the best way to get a person immunized."

The end-all, according to Stevermer, is that the influenza vaccine continues to prevent serious illness and death.

"We think that immunization for as many people as possible is the primary goal, and while there is some remaining concern about LAIV for A (H1N1)pdm09, the vaccine still should work against the other strains it contains," he said.

Additional Flu Vaccine Updates

Beyond the ACIP's recommendation for LAIV's inclusion, there weren't many changes made for the 2018-19 flu season.

Vaccine virus strains included in the 2018-19 U.S. trivalent influenza vaccines will be an A/Michigan/45/2015 (H1N1)pdm09-like virus, an A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus and a B/Colorado/06/2017-like virus (Victoria lineage).

Quadrivalent influenza vaccines will contain those three viruses and an additional influenza B vaccine virus, a B/Phuket/3073/2013-like virus (Yamagata lineage).

Next, two of the recommended IIV4 vaccines had their age indications expanded, Stevermer said.

"Afluria Quadrivalent's age range was expanded from 18 years and older to 5 years and older," he said. "Fluarix Quadrivalent was previously licensed for age 3 and older and is now licensed for age 6 months and older."

In addition, the CDC updated its list of acceptable, age-appropriate indicated vaccines for patients with a history of egg allergy to include LAIV4.

"People who have had a reaction to eggs involving symptoms beyond urticaria should receive their vaccine in a setting prepared to manage a severe allergic reaction," Stevermer said. "A history of a severe allergic reaction to influenza vaccine remains a contraindication to future use of the vaccine."

Stevermer's final note to family physicians as they prepare for the upcoming flu season: "Vaccinate your patients; start as soon as you can, and vaccinate as many as you can."

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