, according to an analysis published in Vaccine.
Dr. James D. Nordin
The data corroborate other research indicating that live attenuated influenza vaccine (LAIV) is safe for children with asthma older than 2 years and suggest that the choice of vaccination in this population should be based on effectiveness, according to James D. Nordin, MD, MPH, a clinical researcher at HealthPartners Institute in Minneapolis, and colleagues.
Children and adolescents with asthma have an increased risk of morbidity if they contract influenza. They represent a disproportionate number of pediatric influenza hospitalizations and have been a focus of efforts to vaccinate children against influenza. Since 2003, the inactivated influenza vaccine (IIV) and the LAIV have been available. Research indicates that LAIV is more effective than IIV at preventing culture-confirmed influenza in children. Two studies found an increased risk of wheezing in children who received LAIV, but other studies failed to replicate these findings.
A retrospective cohort study
Dr. Nordin and associates conducted a retrospective observational cohort study to investigate whether use of a guideline recommending LAIV for children aged 2 years and older with asthma increased the risk of lower respiratory events within 21 or 42 days of vaccination, compared with standard guidelines to administer IIV in children with asthma. The investigators drew data from two large medical groups with independent clinical leadership that serve demographically similar populations in Minnesota. One group (the LAIV group) switched its preference for all children from IIV to LAIV in 2010. The control group continued using IIV for children with asthma throughout the study period. Each group operates more than 20 clinics.
The investigators included children and adolescents aged 2-17 years who presented during one or more influenza season from 2007-2008 through 2014-2015. Eligible participants had a diagnosis of asthma or wheezing, received one or more influenza vaccines, had continuous insurance enrollment, and had at least one primary care or asthma related subspecialty encounter. They excluded patients with contraindications for LAIV (e.g., pregnancy, malignancy, and cystic fibrosis) and those with any hospitalization, ED visit, or outpatient encounter for a lower respiratory event in the 42 days before influenza vaccination.
Dr. Nordin and colleagues used a generalized estimating equation regression to estimate the ratio of rate ratios (RORs) comparing events before and after vaccination between the LAIV guideline and control groups. The researchers examined covariates such as age, gender, race or ethnicity, Medicaid insurance for at least 1 month in the previous year, neighborhood poverty, and neighborhood rates of asthma.
No increased risk
The investigators included 4,771 children and 7,851 child-influenza records in their analysis. During the period from 2007 to 2010, there were 2,215 child-influenza records from children and adolescents included from the LAIV group and 735 from the IIV guideline group. From 2010 to 2015, there were 3,767 child-influenza records in children and adolescents from the LAIV group and 1,134 from the IIV guideline group. After the LAIV group adopted the new guideline, the proportion of patients receiving LAIV increased from 23% to 68% in the LAIV group and from 7% to 11% in the control group.