A population-based study in Kilifi, Kenya, highlights significant gaps in immunity to varicella zoster virus (VZV), with nearly 40% of adults remaining vulnerable to infection.

New research conducted in Kilifi, Kenya, has uncovered concerning trends in immunity to varicella zoster virus (VZV), commonly known as chickenpox. The study analyzed blood samples collected between 2009 and 2021, revealing that a substantial portion of the population, particularly adults, remains susceptible to the virus. This is especially notable as Kenya does not currently include the varicella vaccine in its national infant immunization program.

The findings show that only 38.4% of children under 15 years of age had developed immunity to VZV, with seroprevalence increasing with age. Among children aged 0–4 years, just 13.3% were immune, while this figure rose to 60.9% in those aged 10–14 years. The study also identified that children aged 5–9 years experienced the highest rate of new infections, underscoring the virus’s rapid spread within this age group.

Alarmingly, the research indicates that approximately 40% of individuals entering adulthood remain vulnerable to VZV, posing a heightened risk of severe complications, particularly for pregnant women and older adults. Experts suggest that introducing a varicella vaccine into Kenya’s immunization program could significantly reduce infections across both pediatric and adult populations, potentially preventing severe disease outcomes and improving public health.