Risk of Worsening Asthma From LAIV Unfounded

Use of live attenuated influenza vaccine (LAIV) does not present an increased risk for exacerbation of asthma in young children, according to a study published in Vaccine.¹ In fact, for children aged 2 years or older with asthma or a history of asthma, the LAIV had a reduced risk compared with the inactivated influenza vaccine (IIV).

Recommendations from the Advisory Committee on Immunization Practices (ACIP) released from 2007 to 2014^2-6 have specifically cautioned against the use of LAIV in children with asthma, based on limited evidence from 2 studies of potential wheezing as an adverse effect, although asthma was not a study outcome in either case, the authors reported.^7,8 A number of other studies conducted since then found no indication of exacerbations associated with the use of the live virus^9-16; however, this was not addressed in the ACIP recommendations.

For the current study, the investigators looked retrospectively at the actual incidence of adverse events in a large-scale database from the Kaiser-Permanente Northern California healthcare system. They captured 387,633 immunization records for children aged 2 through 17 years with any history of asthma who were vaccinated between July 1, 2007, and March 31, 2014. As adherence to ACIP recommendations was at the discretion of the medical provider, the authors found a substantial number of children in the database with asthma who were administered live virus: 56,826 (15%) were given LAIV compared with 330,807 (85%) who received IIV.

Exacerbations of asthma were associated with having a recent history of asthma, regardless of the type of vaccine administered. Confirmed exacerbations treated as outpatients occurred in 70% of both the LAIV (591/846) and IIV groups (403/572) with a remote history. Surprisingly, the exacerbation rates were higher for IIV during the risk interval of 1 to 14 days after vaccination than after LAIV (257/100,000 and 113/100,000, respectively).

The important difference, the authors noted, was that the exacerbation trends for LAIV in children with asthma indicated a mild improvement compared with the IIV. Risk rates for an inpatient or emergency department-treated exacerbation among IIV-vaccinated children showed little change between the risk interval and the comparison interval (odds ratio, 0.97; 95% CI, 0.82-1.15), whereas the comparative rate among children given LAIV was lower during the risk interval than the comparison interval (odds ratio, 0.39, 95% CI, 0.17-0.90). Likewise, the risk for an outpatient exacerbation was also lower in the LAIV group, while remaining the same in the IIV group.

“We cannot speak as to whether or not the findings are sufficient to modify ACIP guidelines,” coauthor G. Thomas Ray, MBA, senior data consultant at the Kaiser Permanente Vaccine Study Center and Division of Research, Kaiser Permanente Medical Care Program, Oakland, California, told Pulmonology Advisor. He added that despite recommendations in the 2016 season not to use the LAIV because of poor effectiveness, “some providers may elect to use LAIV, it continues to be recommended outside the [United States], and may again be recommended for use in the [United States] in future seasons.”

Disclosures

G. Thomas Ray has received research support on grants to Kaiser Permanente Division of Research in the past 3 years from Pfizer, Merck & Co, Genentech, and Purdue Pharma. Roger Baxter has received research grants through his institution from MedImmune, GlaxoSmithKline (GSK), Sanofi Pasteur, and Protein Science. Nicola P. Klein has received research grants through her institution from MedImmune, GSK, Sanofi Pasteur, Novartis (now GSK), Protein Science, Merck & Co, and Pfizer.