OBJECTIVES : Over 99% of people aged ≥50 years old have been infected with the varicella-zoster virus (VZV), which causes chickenpox. VZV remains dormant in a person’s body but reactivates in about 33% to cause herpes zoster (HZ, shingles), associated with age-related decline in immunity. This systematic literature review (SLR) aims to summarize worldwide HZ incidence in the ≥ 50 years old population.

METHODS : A systematic search on HZ incidence was conducted in PubMed, Embase and the Virtual Health Library from January 2002 until December 2018. Articles were screened against pre-determined criteria. This review follows guidelines set by the Cochrane Collaboration and PRISMA.

RESULTS : Overall, 70 studies were included; 69 articles and 1 grey literature source. Twenty studies were conducted in North America, 30 in Europe, 19 in Asia-Pacific and 1 in Middle East. There were no studies included from South America or Africa. Most studies (n=52) used International Classification of Diseases codes or equivalent codes to define HZ cases, though methodological differences were observed. When comparing the geographical regions, the cumulative incidence was 5.49–8.67 for North America, 5.77–9.85 for Europe and 2.9–19.5 per 1000 population for Asia-Pacific. For the incidence rate, these were 6.6–9.03 for North-America, 5.23–10.9 for Europe and 10.9 per 1000 person-years in Asia-Pacific (one study only). HZ incidence was reported by age group (n=59), gender (n=34), year (n=24), immunocompromised status (n=5) and ethnicity (n=4).

CONCLUSIONS : This SLR showed that HZ incidence in adults ≥50 years old is similar across the geographic regions included. Most studies were conducted in North America and Europe no with a paucity of data for South America and Africa. Future research in this field could benefit from a standard methodology to identify HZ occurrence, assess HZ incidence and better define populations studied.