Asthma Reported Not a Risk Factor for Serious Illness Among Children With Influenza

A new study reported that ‘asthma was not a risk factor for serious illness among children with influenza.’

This study was published on January 14, 2020, and examined whether school‐aged children with asthma were at an increased risk of serious outcomes associated with medically attended, laboratory‐confirmed influenza illness and whether the impact of the influenza vaccination on serious outcomes differed between children with and without asthma.

These researchers found the 1,764 children with lab-confirmed influenza, only 287 (16.3%) had confirmed asthma.

Furthermore, the odds of a serious outcome did not differ between those with confirmed asthma and those without asthma, after adjusting for vaccination status, influenza type/subtype, age, sex, and presence of a high‐risk condition other than asthma.

The children with a serious outcome in this study over 10 flu seasons were more likely to be 5‐8 years old and have ≥5 outpatient visits in the previous year. The incidence of serious outcomes varied by season, but not by influenza type/subtype.

A serious outcome was defined in this study as hospitalization, emergency department visit, and/or pneumonia diagnosis within 30 days of symptom onset.

This study’s finding is good news since children are often hospitalized during flu seasons with asthma the most common underlying condition reported. Some studies have identified asthma as a risk factor for more severe influenza illness, including asthma exacerbations and the need for intensive care. 

These new findings differ from the 2009 flu season when several studies reported ‘asthma was associated with influenza hospitalizations in children.’

‘Asthma may have contributed to influenza severity in children during the 2009 pandemic, but it is unclear whether there is a similar increased risk during seasonal epidemics,’ said this new study.

It is not known whether influenza vaccination reduces the risk of serious influenza illness among children with asthma.

The strengths of this study include systematic recruitment and sample collection from a community cohort with medically attended, laboratory‐confirmed influenza, access to a validated immunization registry, and complete capture of Emergency Department (ED) visits and hospital admissions from the electronic health record. 

This study also has important limitations. 

During most seasons, enrollments occurred in the primary care and urgent care setting, and most children who initially presented to the ED with severe influenza illness were not enrolled. As a result, the study enrollments may have been biased toward children with stable, well‐controlled asthma.

These researchers from Marshfield Clinic Research Institute said ‘additional studies are needed to better understand the role of influenza vaccination in preventing serious outcomes among children with asthma.’

Both studies highlight the importance of influenza prevention through vaccination among all children.

Although vaccination against influenza does not reduce or shorten asthma exacerbations, the intramuscular trivalent vaccine is safe and has a beneficial effect on the quality of life of children with asthma, says the Centers for Disease Control and Prevention (CDC).

Asthma is the most common chronic disease in childhood and is one of the leading causes of hospitalization in the pediatric population. Viral infections of the respiratory tract, including influenza, are the main causes of asthma exacerbations.

The CDC recommends that people 6 months of age and older get a flu vaccine every year to protect against getting the flu and complications from flu.

During 2017, about 63 percent of children with current asthma had a flu vaccination. Flu vaccination percent decreased with age and did not differ by sex and race/ethnicity, reported the CDC.

Funding information: This work was supported by the CDC through a cooperative agreement (U01 IP000471 and U01 IP001038) with Marshfield Clinic Research Institute and in part through philanthropic support of Marshfield Clinic Research Institute's Summer Research Internship Program. Two researchers reported support from Seqirus for unrelated studies. All other authors report no conflicts of interest.

Children’s vaccination news published by Precision Vaccinations.