Abstract

Varicella, known as chickenpox, is caused by the varicella zoster virus (VZV), with an estimated 84 million cases annually. It primarily affects children, for most of whom it is a self-limiting illness. However, there are an estimated 950 000 disability-adjusted life years attributed to VZV annually, disproportionately affecting lower-income settings. Children with impaired immunity and neonates are particularly at risk for severe varicella. Epidemiology varies between tropical and temperate regions with infections occurring at an earlier age in temperate climates.

Varicella is a vaccine-preventable disease and over 40 countries have a universal one-dose or two-dose paediatric immunisation programme, either administered alone or combined with the measles, mumps and rubella vaccination (MMRV). The UK’s Joint Committee on Vaccination and Immunisation recommended the introduction of MMRV in November 2024. The vaccine, whether monovalent or MMRV, is effective in reducing varicella cases and hospital admissions, and two-dose regimens have further reduced breakthrough infections of shingles, a recognised concern in varicella vaccination programmes. Long-term data on shingles incidence in later life are not yet available and may be mitigated through paired universal shingles vaccination programmes for adults.

Cost-effectiveness studies in high-resource settings support vaccination due to reduced hospitalisations and societal costs, such as missed caregiver employment. However, more research is needed for lower-resource regions to determine whether universal vaccination is feasible and cost-effective. While global varicella elimination is unlikely without sterilising immunity, vaccination can significantly reduce the disease burden, depending on regional epidemiology and available resources.