What's recommended for the 2019 flu shot

Flor M. Munoz, MD, MSc

The American Academy of Pediatrics has released its recommendations for the upcoming flu season, with this year’s recommendation once again including the live, intranasal vaccine.

The American Academy of Pediatrics (AAP) published its recommendations in Pediatrics, and match the recommendations issued this year by the Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices (ACIP).

Flor M. Munoz, MD, MSc, associate professor of pediatrics and molecular virology and microbiology at Baylor College of Medicine and medical director for the transplant infectious diseases program at Texas Children’s Hospital in Houston, helped draft the new recommendations and says this is the first year since the live vaccine was reinstated that the AAP and CDC’s recommendations match. Last year, CDC offered the live, intranasal version of the influenza vaccine as an option for children, but the AAP held back on recommending the vaccine in favor of a longer surveillance period.

“The difference this year is that the AAP and the CDC recommendations match, meaning that they both agree that either the injectable or intranasal influenza vaccine can be used,” Munoz says. “There is not a strong argument to recommend one over the other.”

The ACIP made a preferential recommendation for the intranasal vaccine, FluMist, in 2014 for children aged 2 to 8 years because it appeared to offer better protection. The recommendation was reversed in 2015 over concerns about the vaccine’s efficacy against the 2009 H1N1 strain of influenza. The ACIP reinstated its recommendation for FluMist in 2018, after the vaccine manufacturer was able to demonstrate improved efficacy. The AAP, however, withheld its recommendation in favor of reinstating FluMist, noting that it would prefer to observe the new formulation’s efficacy for a longer period of time before making a decision.

Munoz says AAP’s decision to recommend FluMist is the result of better data showing similar efficacy results between the intranasal and injectable influenza flu vaccines. She notes that protection against H3N2 wasn’t great in either formulation of the vaccine, but both were effective against H1N1.

“This year we do anticipate the majority of the vaccine used will be injectables,” Munoz says, adding that children aged younger than 2 years cannot receive the live, intranasal vaccine.

Munoz also notes that all pediatric influenza vaccines recommended this year are quadrivalent. This has been an ongoing transition from trivalent formulations, she notes. As far as which strains the vaccine will cover, this year’s composition of the flu vaccines this year has been updated to include the influenza A (H1N1) pdm09 and A (H3N2) components. Coverage for B strains is unchanged from previous seasons, according to AAP.

According to ACIP, the 2019-20 quadrivalent flu vaccine will include protection against the A/Brisbane/02/2018 (H1N1) pdm09-like virus, an A/Kansas/14/2017 (H3N2)-like virus, a B/Colorado/06/2017–like virus (Victoria lineage), and a B/Phuket/3073/2013-like virus (Yamagata lineage). Additionally, the US Food and Drug Administration (FDA) expanded the age indication for the Afluria Quadrivalent vaccine this year. The vaccine was previously approved for use in children aged 5 and up, and now can be used in children aged 6 to 35 months. Children aged 6 to 25 months should receive the 0.25 mL dose, and children who are over 36 months of age should receive the 0.5 mL dose, according to ACIP. Pediatricians will have to watch which vaccine they are using, as there are several variations now for children aged 6 to 35 months, Munoz notes.

“Make sure to look at the vaccine brand and formulation,” Munoz advises. “There are different options for babies aged 6 to 35 months.”

There are now 4 egg-based quadrivalent flu vaccines licensed for children aged 6 months and older, 1 inactivated cell-based quadrivalent vaccine for children aged 4 years and older, and 1 quadrivalent live attenuated vaccine for children aged 2 years and older. New formulas of vaccines with a volume of 0.5 mL have been approved for children aged 6 to 36 months depending on the vaccine formula used. Children aged 36 months and older should receive the 0.5 mL dose, according to the recommendations. The ACIP recommends that a 0.25 mL dose is indicated for Afluria Quadrivalent, 0.5 mL doses are indicated for Fluarix and FluLaval quadrivalents, and either a 0.25 mL or 0.5 mL dose can be used of Fluzone Quadrivalent. The dose for the intranasal vaccine, FluMist, is 0.2 mL, or 0.1 mL in each nostril.

Which vaccine is chosen may also depend on supplies, with some manufacturer’s anticipating shipping delays due to the timing of the World Health Organization’s decision on which flu strains to include in this year’s vaccine.

As for timing, AAP recommends that children aged 6 months to 8 years who are receiving the flu vaccine for the first time, or who received only 1 dose prior to July 2019, be vaccinated with 2 doses of the vaccine by the end of October. Children who need only 1 dose, regardless of age, should also be vaccinated by the end of October, AAP states, reflecting the recommendation from ACIP.

There is also a new antiviral treatment available to pediatric patients, according to AAP. Baloxavir marboxil was licensed in 2018 for early treatment of influenza in patients aged older than 12 years who have been sick for less than 2 days. The new medication requires only a single dose, notes AAP, adding that clinical trials of the drug are still ongoing in hospitalized patients. The AAP recommends that any children hospitalized with suspected or confirmed influenza be treated with some form of antiviral medication approved for their age group, regardless of the duration of symptoms.