A study on the influence of obesity on the protection after influenza vaccination in children aged 9-17 years.
A prospective pilot study investigating the impact of obesity on seroprotection after influenza vaccination in children aged 9-17 years.
Women's and Children's Hospital
50 participants
Jul 4, 2019
Interventional
Conditions
Summary
Influenza is a highly infectious respiratory virus that can affect people of all ages. Every year, influenza causes 35 million cases of severe disease worldwide including more than 250,000 deaths. The most effective method of protection from influenza infection is by vaccination. However vaccination is often not 100% effective, and various factors can influence the immune response achieved following vaccination. One such factor that may play an important role in altering the immune responses to influenza vaccination is obesity. Studies among adults have shown that significant obesity puts individuals at increased risk of more severe disease and a more prolonged disease course from influenza. In addition, the effectiveness of influenza vaccination may differ between obese and non-obese individuals. Studies among adults vaccinated with influenza vaccination showed that obese individuals developed significantly higher rates of influenza as compared to non-obese individuals suggesting that influenza vaccination may be less effective in obese than in non-obese adults. Other studies have shown that obese individuals had a reduced cell-mediated immune response to influenza vaccination as compared to non-obese individuals. Most of the studies exploring vaccine effectiveness in obese individuals have been conducted in adults and there are currently no published studies examining differences in immune responses between obese and non-obese children or adolescents in response to influenza vaccine. It is important to further explore and understand how the obese state alters immune function and response to influenza vaccination, and the impact that young age may have on these changes. Understanding mediators of lowered immune responses following vaccination is important for public health policy and programs, and will provide evidence which could be highly translatable to immunization policy and inform vaccination strategies for obese populations. This study will enrol 25 non-obese (BMI 5-<95th percentile) and 25 obese (BMI >=95th percentile) children aged 9-17 years of age (N=50) and include 3 study visits. Participants will receive a single dose of licensed quadrivalent influenza vaccine at visit 1. Blood samples will be collected at all 3 visits (visit 2 and 3 will occur 1 and 6 months post-vaccination). Influenza specific antibody concentrations and haemaggluttination inhibition assay (HIA) titres will be measured on blood samples from all three time-points. A HIA titre of 1:40 is the established level of protection for influenza vaccination. Serum antibody concentrations will be log transformed to provide geometric mean concentrations (GMC). The protective HIA titres and GMC will be compared between obese and non-obese cohorts using linear regression models with effects expressed as mean differences and 95% confidence intervals. Both unadjusted and adjusted analyses will be performed, with adjustment for biologically plausible potential confounders.
Eligibility
Inclusion Criteria7
- All participants must satisfy ALL the following criteria at study entry:
- Participants are healthy children aged between 9-17 years at the time of enrolment.
- Participants who, in the opinion of the study staff, can and will comply with the requirements of the protocol (eg return for follow-up visits, blood collection).
- Participants who can provide assent and have a parent willing to provide consent.
- Additional criteria specific to cases and controls include:
- Cases - Obese children (BMI >=95th percentile for age and gender) aged 9-17 years. Total number to be enrolled is 25 cases.
- Controls - Non-obese children (BMI 5th - <95th percentile for age and gender) aged 9-17 years. Total number to be enrolled is 25 controls.
Exclusion Criteria12
- Presence of any of the following criteria will exclude the subject from receipt of influenza vaccination as part of the study:
- History of serious medical conditions (eg cardiac, respiratory, renal, hepatic disorders, diabetes mellitus requiring treatment with insulin).
- Any syndromal and/or endocrinological causes for obesity.
- History of seasonal influenza vaccination within the last six months prior to enrolment.
- History of any immunosuppressive condition (eg HIV infection) or on immunosuppressing medication.
- Any contraindication to influenza immunisation according to the Australian Immunisation Handbook.
- Anaphylaxis following a previous dose of any influenza vaccine
- Anaphylaxis following any vaccine component.
- History of egg allergy.
- History of Guillain Barre syndrome.
- Bleeding diathesis or condition associated with prolonged bleeding that may contraindicate intramuscular injection or blood draw.
- Any major illness that, in the investigator’s judgment, will substantially increase the risk associated with the subject’s participation in the study, or interfere with the evaluation of the study objectives.
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Interventions
This is a pilot case control study to study the effect, if any, of obesity, on the immune response to the annual licensed quadrivalent influenza vaccination in Australian children aged 9-17 years. Cases - 25 obese children (BMI >=95th percentile for age and gender) aged 9-17 years. Controls - 25 non-obese children (BMI 5th - <95th percentile for age and gender) aged 9-17 years. The dose of the influenza vaccine is 0.5 ml administered as a single dose IM injection. All vaccines will be administered by a qualified and experienced practitioners (medical officer or registered nurse) within the unit, according to current vaccination guidelines. All participants will have bloods samples collected by the recruiting medical officer before vaccination and at the follow-up visits at 1 and 6 months after vaccination.
Locations(1)
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ACTRN12617001086358