Study: Live Attenuated Virus Flu Vaccines Do Not Exacerbate Asthma in Children

There is no increased risk of asthma exacerbation for children (age 2-18) as a result of influenza immunizations with live attenuated influenza vaccines (LAIV), concluded a May 2017 study published in the journal Vaccine.

The joint study investigated whether nasally-administered LAIVs, such as FluMist, had an increased risk of exacerbating asthma symptoms in children, as compared to IIV vaccinations.

Researchers from the Kaiser Permanente Vaccine Study Center and Division of Research in Oakland, California, and the Immunization Safety Office of the Centers for Disease Control and Prevention in Atlanta, Georgia noted that LAIV may offer a decreased risk of exacerbations compared to inactivated influenza vaccine (IIV) that is currently recommended for children and adolescents with asthma.

G. Thomas Ray, MBA (pictured), Senior Data Consultant at Kaiser Permanente’s Division of Research, led the analysis of study data collected between 2007 and 2014 from Kaiser Permanente Northern California (KPNC). The aim of the investigation was to determine whether there was a difference between the live versus the inactive virus vaccines among children with asthma.

Ray noted that from the 2007 to the 2016 influenza seasons the “Advisory Committee on Immunization Practices (ACIP) recommended the use of either LAIV or IIV in healthy children and adolescents [over] 2 years of age, but either recommended, or cautioned, against use of LAIV in children with asthma, depending on the age of the child.”

The recommendation from the ACIP to avoid use of LAIV in children with asthma was based on a 2004 safety trial on the use of cold-adapted trivalent intranasal influenza virus vaccine (CAIV) also conducted by Kaiser Permanente’s Vaccine Study Center associates.

The 2004 double blind, placebo-controlled, trial, published in The Pediatric Infectious Disease Journal concluded that there was an increased risk of wheezing in children between 18-35 months of age after use of the CAIV. Ray pointed out that the 2004 trial did not focus on asthma specifically as an endpoint of that study, and that prior to the 2017 study, little research “examined adverse outcomes following LAIV in children with asthma or related respiratory conditions.”

The 2017 study focused exclusively on children with a history of asthma with the goal of evaluating the safety of LAIV in comparison to IIV “with respect to asthma exacerbations and other adverse outcomes in children and adolescents.” The study data were drawn from a large pool of retained information on all IIV and LAIV immunizations of children with asthma performed on KPNC patients between the ages of 2 and eighteen. The study classified children into 3 groups based on asthma severity: children with current or recent persistent asthma, children with current or recent, not persistent asthma, and children with a remote history of asthma.

The study monitored asthma exacerbation based on acute inpatient hospitalization, ED visits, and “chart-confirmed outpatient asthma” visits to KNPC facilities. According to Ray, medical records were reviewed to “validate that the [outpatient] visits were for acute asthma exacerbations rather than routine asthma management or follow up.”

Data were examined to determine if there was a difference in the odds of an asthma event occurring post-immunization for children with asthma. The team analyzed 154,994 children’s medical records, many of whom had received several influenza vaccinations in the 7-year span between 2007 and 2014. Of the 387,633 vaccinations analyzed, 85% were IIV and 15% were LAIV.

The study results determined that there was no temporal pattern connecting IIV or LAIV immunizations with asthma exacerbations in the 42 days following immunization. The study also determined that risk factors for asthma exacerbations with patients receiving LAIV were statistically lower than with patients receiving IIV.

The findings, Ray noted, were “consistent for each asthma severity subset.” The authors suggested that “despite the ACIP’s caution against it”…”concerns about administering LAIV to children with asthma — especially those with current or recent, not persistent asthma or only a remote history of asthma – may not be warranted.”

The article “Asthma Exacerbations among Asthmatic Children Receiving Live Attenuated versus Inactivated Influenza Vaccines” was published in the May 2017 issue of Vaccine.

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