Clinical effectiveness of conventional influenza vaccination in asthmatic children

Abstract

SUMMARYInfluenza immunization rates among young asthmatics remain unsatisfactory due to persistent concern about the impact of influenza and the benefits of the vaccine. We assessed the effectiveness of the conventional inactivated trivalent sub-unit influenza vaccine in reducing acute respiratory disease in asthmatic children. We conducted a two-season retrospective cohort study covering the 1995-6 and 1996-7 influenza outbreaks in 22 computerized primary care practices in the Netherlands. In total, 349 patients aged between 0 and 12 years meeting clinical asthma-criteria were included ; 14 children were lost to follow-up in the second season. The occurrence of physician-diagnosed acute respiratory disease episodes including influenzalike illness, pneumonia, bronchitis, bronchiolitis, asthma exacerbation and acute otitis media in vaccinated and unvaccinated children were compared after adjustments for age, prior health care and medication use. The occurrence of acute respiratory disease in unvaccinated children was 28 % and 24 % in the 1995-6 and 1996-7 season, respectively, and was highest in children under 6 years of age (43 %). The overall pooled clinical vaccine effectiveness was 27 % (95 % confidence interval k7 to 51%, P l 0n11) after adjustments. A statistically higher vaccine protectiveness of 55 % (95 % CI 20-75 %, P l 0n01) was observed among asthmatics under 6 years of age compared with k5 % in older children (95 % CI k81 to 39 %).

Clinical Effectiveness of Influenza Vaccination in Persons Younger Than 65 Years With High-Risk Medical Conditions

“…32 The number of febrile influenza A episodes was reduced by 68% 33 in a study among children, and acute respiratory disease was reduced by 55% among children with asthma in a previous small cohort study by our group. 34 In the present study, we observed a 43% reduction in GP visits for acute respiratory disease and acute otitis media during the 1999-2000 influenza epidemic, an estimate that is in accordance with most of these earlier small-scale studies. However, we lacked adequate power to establish a potential association between vaccination status and the more severe end points (ie, hospitalization or death) among these children.…”

Risk factors and outcomes among children admitted to hospital with pandemic H1N1 influenza

“…Such studies should focus on age and underlying asthma in particular. There are limited data to support the efficacy of influenza vaccination in reducing asthma exacerbations, 17 particularly in older children, 18 although previous concerns about safety in asthma have been assuaged. Asthma has therefore been an indication for influenza vaccination for several years, but uptake is low.…”

Prevention and Control of Seasonal Influenza with Vaccines

“…In a nonrandomized controlled trial during the 1992-93 season involving 137 children who had moderate to severe asthma, vaccine efficacy against laboratory-confirmed influenza A(H3N2) infection was 54% among children aged 2 through 6 years and 78% among children aged ≥7 through 14 years; vaccine efficacy against laboratory-confirmed influenza B infection was 60% among children aged ≥7 through 14 years, but nonsignificant for the younger age group (193). In a two-season study of 349 asthmatic children, IIV3 vaccine was associated with a 55% reduction in the occurrence of ARI in children aged <6 years (95% CI = 20-75; p = 0.01), but no association was noted among children aged 6 through 12 years (194).…”