OBJECTIVES: Data on herpes zoster (HZ) burden are scarce in Latin America. In 2023, an adjuvanted recombinant zoster vaccine (RZV) launched in Argentina, Brazil, and Mexico. To estimate HZ burden and impact of vaccinating adults aged ≥50 years in Peru, Ecuador, and five Central American and Caribbean (CARICAM) countries (Panama, Guatemala, Dominican Republic, Costa Rica, Trinidad & Tobago), modelling analyses were conducted for each country.

METHODS: A static multicohort Markov model with one-year cycle length and with a lifetime horizon was adapted into each country. Demographics were obtained from the United Nations, HZ incidence from a worldwide meta-regression, proportions of post-herpetic neuralgia (PHN) and other (ocular, neurological, cutaneous, and other non-PHN) complications from published regional studies, and vaccine efficacy from phase 3 clinical trials (ZOE-50, ZOE-70). First-dose coverage and second-dose compliance of RZV were assumed to be 35% and 75%, respectively. One-way sensitivity analyses (OWSA) were conducted to assess parameter uncertainty.

RESULTS: Without RZV, there would be total of 3,636,829 HZ cases (Peru: 1,416,753, Ecuador: 773,097, CARICAM: 1,446,979), 933,327 PHN cases (Peru: 362,780, Ecuador: 199,792, CARICAM: 370,756), and 1,089,687 non-PHN complications (Peru: 424,495, Ecuador: 231,640, CARICAM: 433,552).

Introducing RZV under 35% coverage could avoid 734,491 (20%) HZ cases (Peru: 289,841, Ecuador: 152,835, CARICAM: 291,815), 179,664 (19%) PHN cases (Peru: 70,894, Ecuador: 37,605, CARICAM: 71,165), and 220,072 (20%) non-PHN complications (Peru: 86,844, Ecuador: 45,793, CARICAM: 87,435).

The numbers needed to be vaccinated to avoid one HZ case were 9-15 across countries, and 35-68 to avoid one PHN case.

OWSA showed that first-dose coverage, HZ incidence, and vaccine efficacy waning had the largest impact on the estimated number of HZ cases avoided.

CONCLUSIONS: This modelling study suggests a substantial HZ disease burden in Central and South America and RZV vaccination may be an effective option to significantly reduce HZ burden.

Funding: GlaxoSmithKline Biologicals SA (VEO-000673).