Live, Attenuated Influenza Vaccine Safe in Children with Asthma

NEW ORLEANS, LA—Concerns about administering live, attenuated influenza vaccine (LAIV) in children with asthma “may not be warranted,” according to authors of a study presented at IDWeek.

“Among children and adolescents with a history of asthma, we found no evidence that LAIV was associated with an increased risk of asthma exacerbations regardless of severity,” reported Nicola P. Klein, MD, PhD of the Kaiser Permanente Vaccine Study Center, Oakland, CA.

Although the Advisory Committee on Immunization Practices has cautioned against use of LAIV in children with asthma, the evidence base on LAIV safety in these children is limited, she noted.

To investigate whether or not LAIV, is associated with asthma exacerbations in children compared with inactivated influenza vaccine (IIV), Dr. Klein and colleagues identified IIV and LAIV immunizations administered to children with asthma aged 2 to 17 years, between July 1, 2007 and March 31, 2014 in the Kaiser Permanente Northern California health care system.

Children were categorized by asthma severity at the time of immunization: “active, persistent”; “active, not-persistent”; or “remote history.” Asthma exacerbation was defined as a hospitalization or emergency department visit during which the child received a principal diagnosis of asthma.

In children with remote history of asthma, chart-confirmed outpatient exacerbations were analyzed.

Using a case-centered approach—and calculating separately for LAIV and IIV—the investigators determined the odds of a child being vaccinated in the exposure interval, defined as 1 to ≤14 days, and in the comparison interval, defined as 29 to ≤42 days prior to the asthma exacerbation, and calculated the ratio of those odds. 

The team identified 387,633 immunizations representing 143,013 children receiving IIV and 35,624 receiving LAIV. Children who were administered LAIV compared with IIV were less likely to have active, persistent, asthma, 25% vs. 44%, respectively, and more likely to have remote history of asthma, 47% vs. 25%.

Among children with asthma (all types) who were vaccinated with IIV, the odds ratio (OR) of exacerbation of asthma was 0.97 (95% CI, 0.82–1.15); for LAIV, the adjusted OR was 0.39 (95% CI, 0.17–0.90). In a difference-in-differences analysis adjusted for age, gender, calendar time and time since immunization, LAIV vs. IIV was associated with a decreased risk of asthma exacerbations (OR 0.40; 95% CI, 0.17–0.95), Dr. Klein reported. After analyzing outpatient exacerbations, no differences were found between the vaccines (difference-in-differences OR 0.63; 95% CI, 0.35–1.15, n.s.). 

LAIV was not associated with increased risk of outpatient asthma exacerbations among patients with remote histories, Dr. Klein noted. That finding is “reassuring since these children would be the most likely to receive LAIV,” she said.

“This study suggests that, among children 2 years old or older with asthma, those vaccinated with LAIV compared with IIV did not have an increased risk of asthma exacerbations,” Dr. Klein concluded.