Influenza Vaccine

Jessie Chung, MPH, on the Return of the Nasal Spray Flu Vaccine

When the CDC’s Advisory Committee on Immunization Practices (ACIP) released its annual vaccine recommendations for the 2018-2019 season, a familiar face had rejoined the list: FluMist, or the nasal spray vaccine.1

Also known as the quadrivalent live attenuated vaccine (LAIV4), it had not been recommended for the previous 2 influenza seasons due to poor effectiveness against H1N1 strains in children. However, this year’s LAIV4 formulation utilizes a different H1N1 virus.1

The effectiveness of LAIV4 formulations from various influenza seasons was compared with that of the inactivated influenza vaccine (IIV) in a study recently published in Pediatrics.2

Researchers found that LAIV4 and IIV demonstrated similar vaccine effectiveness against influenza types B and A/H3N2—last year’s dominant strain. However, LAIV4 was found to be only 20% effective against A/H1N1pdm09, whereas IIV was 67% effective against this strain.2

Consultant360 discussed the clinical implications of these findings further with study author Jessie Chung, MPH, epidemiologist at the CDC.

Consultant360: In your study, you and your colleagues found that LAIV4 was only 20% effective against the A/H1N1pdm09 strain, while IIV was 67% effective against this strain. Did you anticipate this finding?

Jessie Chung: Our findings of lower effectiveness of LAIV compared to IIV against A/H1N1pdm09 virus in the US are consistent with the findings from the individual studies included.

C360: Despite its reduced effectiveness compared with IIV, is LAIV4 still a beneficial option? Might the new LAIV4 formulation demonstrate greater vaccine effectiveness than previous formulations?

JC: Overall, LAIV provided statistically significant protection against medically attended influenza, although effectiveness was reduced compared with IIV. Since the influenza seasons included in our analysis, the H1N1pdm09 component in LAIV has been updated. Vaccine effectiveness estimates against H1N1 last season in the United Kingdom are encouraging and suggest effectiveness of LAIV against that virus in the United States will be higher this season.

C360: What should providers discuss with parents who express interest in having their child receive the LAIV4 vaccine instead of the IIV?

Parents should know that the most important thing they can do to protect their children against influenza is to vaccinate them. Influenza vaccination can reduce the risk of influenza-associated hospitalization and can be life-saving in children. A study published in Pediatrics in 2017 demonstrated that influenza vaccination provided protection against influenza-associated deaths among children.3

The CDC recommends annual influenza vaccination for everyone 6 months and older with any licensed, age-appropriate influenza vaccine (IIV, RIV4, or LAIV4), with no preference expressed for any one vaccine over another.

—Christina Vogt


  1. Grohskopf LA, Sokolow LZ, Broder KR, et al. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices—United States, 2018–19 influenza season. Recommendations and Reports. 67(3);1–20.
  2. Chung JR, Flannery B, Ambrose CS, et al. Live attenuated and inactivated influenza vaccine effectiveness [published online January 7, 2019]. Pediatrics. doi:10.1542/peds.2018-2094.
  3. Flannery B, Reynolds SB, Blanton L, et al. Influenza vaccine effectiveness against pediatric deaths: 2010-2014. Pediatrics. 2017;139(5). doi:10.1542/peds.2016-4244.