Carryn S, Cheuvart B, Povey M, et al. - Data from countries with universal varicella vaccination yielded no consistent evidence of decreased varicella-zoster virus (VZV) exposure among older adults.

• Humoral and cell-mediated immunity (CMI), as markers of varicella-zoster virus (VZV) exposure, were assessed among adults aged ≥ 50 years.

• Data from placebo recipients in a large multinational clinical trial (ZOE-50, NCT01165177) were repurposed.

• On the basis of their varicella vaccination program characteristics, countries were clustered as having high, moderate or low VZV circulation.

• Between 17 countries (12 high, two moderate, three low circulation), significant variation in VZV-specific humoral immunity was evident, but no variation was seen based on VZV circulation.

• Participants from two high vs one low circulation countries showed no significant differences in VZV-specific CMI.

• In 3/5 sensitivity analyses, high VZV circulation countries more frequently showed increases in CMI.