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Adjuvant-attenuated symptom severity of influenza infections in vaccinated children
Charlotte Switzer1, Chris P Verschoor1,2, Eleanor Pullenayegum1,3,4
1Department of Health Methods, Evaluation and Impact, McMaster University, Hamilton, ON, Canada.
Insights
Adjuvanted influenza vaccines may reduce fever and systemic symptoms in children, particularly during influenza A infections. This finding suggests potential benefits for symptom severity in vaccinated children experiencing breakthrough infections.
Area of Science:
- Pediatric Infectious Diseases
- Vaccinology
- Clinical Trials
Background:
- Young children face high risks for severe influenza complications.
- Influenza vaccination offers protection and reduces symptom severity in breakthrough cases.
- This study compared symptom severity between adjuvanted trivalent and quadrivalent inactivated influenza vaccines in children.
Purpose of the Study:
- To assess the association between adjuvanted trivalent seasonal influenza vaccine (aTIV) and symptom severity in children with laboratory-confirmed influenza.
- To compare aTIV with quadrivalent inactivated influenza vaccine (QIV) in terms of influenza symptom severity outcomes.
Main Methods:
- A cluster randomized controlled trial was conducted in Canadian Hutterite colonies over three influenza seasons (2016-2019).
- Children received either QIV or MF59-adjuvanted aTIV.
- Symptom severity outcomes in PCR-confirmed influenza cases were analyzed using multivariable generalized negative binomial regression.
Main Results:
- No significant difference in total symptoms or duration of symptoms was found between aTIV and QIV groups (p > 0.05).
- aTIV vaccination was associated with a significant 74% reduction in fever severity.
- In influenza A infections, aTIV was linked to significantly reduced systemic symptoms (IRR: 0.16, p=0.01).
Conclusions:
- Vaccine formulation impacted symptom severity, with aTIV associated with attenuated fever and reduced systemic symptoms in influenza A.
- While overall symptom burden was similar, aTIV showed a specific benefit in reducing fever severity.
- Further research may explore the nuanced effects of different influenza vaccine formulations on pediatric symptomology.
Background:
Young children are at high risk for developing complications of influenza, as well as severe clinical presentation of disease. Vaccination provides direct protection and reduces symptom severity in breakthrough infections. We assessed whether adjuvanted trivalent seasonal influenza vaccine is associated with symptom severity in children who developed laboratory-confirmed influenza, as compared to children who received quadrivalent inactivated influenza.
Methods:
A cluster randomized controlled trial of influenza vaccines in Canadian Hutterite colonies was conducted from the 2016-2017 to the 2018-2019 influenza season. Children were vaccinated with either quadrivalent inactivated influenza vaccine (QIV), or the MF59 adjuvanted trivalent influenza vaccine (aTIV). We assessed children who developed PCR-confirmed influenza infection for symptom severity outcomes using multivariable generalized negative binomial regression.
Results:
Among vaccinated children, 49 infections were observed across 1779 person-days. Vaccine formulation (aTIV vs QIV) was not significantly associated with composite symptom outcomes, including total number of symptoms or total duration of symptom presentation (p > 0.05 for all outcomes). Receipt of aTIV vaccination was significantly associated with attenuation of fever, with an estimated 74% reduction in fever severity. In influenza A type infections, adjuvanted vaccination was significantly associated with reduced systemic symptoms (incidence rate ratios: 0.16, 95% confidence intervals: 0.03, 0.64, p = 0.01). No associations were observed between vaccine formulation and symptom severity in influenza B infections.
Conclusions:
In vaccinated children who develop an influenza infection, vaccine formulation was associated with attenuated fever severity, leading to reduced systemic symptoms. In influenza A infections, adjuvanted vaccination was significantly associated with reduced systemic symptoms.
Conclusions:
Clinical Trials Registry: NCT02871206.
