Quality of Life Impact of Varicella on Children and Their Families in the UK: The QoLPoX Study.

Background: Varicella (chickenpox) is a ubiquitous disease of childhood in the UK, yet highly effective and safe vaccines have been routinely used in other countries for years. Previous UK assessments of varicella vaccines did not meet the National Institute of Health and Care Excellence £20-30k/quality-adjusted life year (QALY) cost utility threshold, in part due to limited data quantifying the quality of life (QoL) lost.

Methods: We carried out a prospective multicenter observational study recruiting families while their child had acute varicella or secondary complications. We recruited severe cases admitted to hospital and mild community cases from childcare. QoL was assessed using standard tools: EQ5D-5L + CHU9 for children and EQ5D-5L for both carers. Assessments were carried out daily in the hospitalized arm until discharge, weekly for 1 month and then at 6 months. In the community arm, assessments were daily until back to normal health.

Results: Between 2018 and 2022, we obtained data on 55 community and 140 hospitalized cases. Mean QALY loss in children was 6.7 (6.1-7.0)/1000 community cases and 46.7 [95% confidence interval (CI): 44.5-51.6]/1000 hospitalized. Primary carers lost 2.4 (95% CI: 2.2-2.8)/1000 community cases or 20.2 (95% CI: 19.4-22.3)/1000 hospitalized. Secondary carers lost 0.7 (0.3-0.7)/1000 community cases or 15.8 (95% CI: 15.5-18.1)/1000 hospitalized.

Conclusions: This detailed prospective assessment of QoL loss from varicella found it to be 1.5-10× larger in children than used in previous economic assessments and quantified the QALY loss for both primary and secondary carers. These data have been used to parameterize new assessments of UK varicella vaccine cost utility.