Severe Obesity in Children May Not Pose Independent Risk for Influenza Complications

Highlights

• Severe obesity is not an independent risk factor in this study population.

• Fifteen (100%) of 188 cases with BMI ≥99% had a known high-risk condition for influenza complications.

• Fourteen (7%) of 188 cases had no known high-risk condition for influenza complications, all had BMI <99%.

• One hundred seventy four (93%) of 188 cases 2 to <20 years old had a high-risk condition for influenza complications.

Abstract

Purpose

Subsets of children are targeted for influenza vaccination due to known conditions that increase the risk of influenza complications. The purpose of this study was to determine if severe obesity in children suggests targeted vaccination.

Design and methods

A retrospective chart review of a large Midwestern pediatric hospital identified 188 cases of influenza complications (defined as requiring hospitalization or death) aged 2 to <20 years old from August 1, 2010 through June 30, 2013. Severe obesity was defined as body mass index (BMI) ≥99% for age and gender, with patients grouped by severe obesity status (yes vs. no). Cases were reviewed for previously identified risk conditions for influenza complications (e.g., asthma, pneumonia, diabetes), and were classified as having or not having a known high risk condition.

Results

Of 188 cases, 174 (93%) had a high-risk condition, while only 14 (7%) had no known condition. All 14 (100%) with no known high-risk condition had a BMI <99%. All 15 (100%) with BMI ≥99% had a known high-risk condition. The association between severe obesity status and influenza complications was not statistically significant (p = 0.61).

Conclusions

This suggests that severe obesity in children is not an independent high-risk condition for influenza complications defined as requiring hospitalization or resulting in death, once other known influenza risk factors are considered.

Implications

Based on this data, clinicians should not target children for influenza vaccination based on weight status. We cannot comment about whether severe obesity represents increased risk for less severe cases of influenza.

Introduction

Every year otherwise healthy children die from influenza (American Academy of Pediatrics [APA], 2016; Centers for Disease Control and Prevention [CDC], 2017). The Centers for Disease Control and Prevention (2015) reported 146 pediatric influenza related deaths during 2014–2015 influenza season. Overall, the annual total economic burden of influenza is estimated at $87.1 billion, including projected lost earnings from illness and loss of life (Molinari et al., 2007). Children are at an increased risk of hospitalization and death because of influenza complications, compared with adults (Centers for Disease Control and Prevention, 2017). In 2010 the Advisory Committee on Immunization Practice (ACIP) first recommended universal influenza vaccination for all children at least 6 months of age without contraindications (Centers for Disease Control and Prevention, 2011). Despite the availability of a safe and effective influenza vaccination (American Academy of Pediatrics, 2017; Centers for Disease Control and Prevention, 2017; World Health Organization [WHO], 2012) and universal recommendations for influenza vaccination of children and adolescents, many children and adolescents remain unvaccinated each year (Molinari et al., 2007).

In addition to universal vaccination, experts recommend targeted vaccination of high-risk populations, such as children and adolescents with asthma and diabetes to decrease morbidity and mortality related to influenza infection (American Academy of Pediatrics, 2017; Centers for Disease Control and Prevention, 2017; World Health Organization, 2012). Identification of target populations for vaccination is also recommended by World Health Organization (2012) in relation to pandemic preparation and response. Targeting vaccinations to accurately identified, high-risk groups also allows for effective allocation of resources in situations where vaccine supplies do not meet demand.

Starting in 2010 and reconfirmed in 2018 (Centers for Disease Control and Prevention, 2010; Centers for Disease Control and Prevention, 2018b), the CDC indicated that “people who are morbidly obese [Body Mass Index, or BMI, of 40 or greater]” were at increased risk of severe influenza complications, and should be targeted for vaccination. Additional research highlights morbid obesity as a high-risk condition for influenza complications in adults (The Australian and New Zealand Intensive Care (ANZIC) Influenza Investigators, 2009; Barrau et al., 2012; Bergman, Livornese, Sambhara, Santoro, & Dessain, 2011; Gilca et al., 2011; Karlsson, Marcelin, Webby, & Schultz-Cherry, 2012; Kwong, Campitelli, & Rosella, 2011; Louie et al., 2009; Morgan et al., 2010). The CDC does not clearly define what age groups are included in their recommendation. Thus is it unclear whether children and adolescents age 2 to 19 years old, where severe obesity is defined using age- and gender-specific BMI percentiles rather than static BMI values (Ogden, Carroll, Curtin, Lamb, & Flegal, 2010), are at increased risk for complications and should therefore be a targeted vaccination group. Considering the universal vaccination guidelines and subgroup targeting strategies already in place for children and adolescents, it remains unclear if severe obesity represents an increased risk in children.

The objective of this study was to address two questions: First, is severe obesity a risk factor for severe influenza complications (defined as requiring hospitalization or resulting in death) in children and adolescents, beyond already-targeted conditions? Second, should clinicians be targeting children and adolescents with severe obesity for influenza vaccination beyond universal vaccination recommendations?