Varicella: is it time for a global vaccination programme?

Area of Science:

• Virology
• Epidemiology
• Public Health

Background:

• Varicella, or chickenpox, is a viral illness caused by the varicella zoster virus (VZV), affecting millions globally each year.
• While often self-limiting in children, VZV causes significant disability-adjusted life years, disproportionately impacting lower-income regions and posing risks to immunocompromised individuals and neonates.
• Disease epidemiology differs geographically, with earlier onset in temperate climates compared to tropical regions.

Purpose of the Study:

• To review the epidemiology of varicella and the impact of vaccination programs.
• To assess the effectiveness of varicella vaccination, including single and two-dose regimens (alone or as MMRV).
• To evaluate the cost-effectiveness of varicella vaccination and identify areas for future research.

Main Methods:

• Review of existing epidemiological data on varicella zoster virus (VZV) incidence and burden.
• Analysis of data from countries with universal varicella vaccination programs (single or two-dose, monovalent or MMRV).
• Examination of cost-effectiveness studies in high-resource settings and identification of research gaps for lower-resource regions.

Main Results:

• Over 40 countries utilize universal varicella vaccination, demonstrating reduced cases and hospitalizations.
• Two-dose regimens are more effective at preventing breakthrough infections and may reduce shingles incidence.
• Vaccination is cost-effective in high-resource settings, but feasibility and cost-effectiveness in lower-resource areas need further investigation.

Conclusions:

• Varicella vaccination is a key strategy for reducing disease burden, with two-dose schedules offering enhanced protection against VZV and shingles.
• While global elimination is challenging, vaccination significantly mitigates varicella's impact based on regional factors.
• Further research is crucial to optimize vaccination strategies, particularly in resource-limited settings, and to understand long-term shingles incidence.