{
  "abstract": "Background: Costa Rica introduced universal one-dose varicella vaccination in 2007 using a one-dose schedule administered at 15 months of age through the Costa Rican Social Security Fund (CCSS). A previous national study described epidemiological changes through 2014 by comparing pre- and post-vaccination periods; however, contemporary data on subsequent patterns and residual disease burden are limited. We characterized varicella epidemiology and healthcare burden in Costa Rica using the most recent nationally available data. Methods: We conducted a nationwide retrospective descriptive study using aggregated surveillance and administrative data. Outcomes included incidence of reported varicella cases (2015-2022), outpatient and emergency department visits (2019-2024), hospitalizations (2015-2024), in-hospital deaths with a recorded varicella diagnosis (2018-2020), institutional outbreaks, and first-dose vaccination coverage (2018-2024). Results: From 2015 to 2022, reported incidence declined by 84% in males and 83% in females, after increasing through 2019 and declining markedly during the COVID-19 pandemic. Children aged 1-9 years accounted for the largest proportion of reported cases. Among 354 hospitalizations, adults aged 20-44 years accounted for 30.5%. Hospitalizations among children aged ≤4 years decreased by approximately 56% between 2015-2018 and 2021-2024, while annual hospitalizations among adults aged 20-44 years increased from 7 in 2015 to 21 in 2024, representing a 200% increase over the study period. Three deaths occurred during hospitalizations with a varicella diagnosis, all among adults, and one institutional outbreak was identified. First-dose vaccination coverage averaged approximately 94% during 2018-2022 and remained high thereafter. Conclusions: Reported varicella incidence declined substantially during the study period, but circulation and healthcare burden persisted, with hospitalizations increasingly concentrated among adults. Because our analysis lacks a pre-vaccination comparator, these trends cannot be causally attributed to vaccination based on our data alone. The findings support maintaining high first-dose coverage and strengthening surveillance. Further information on individual vaccination history and population susceptibility is needed to evaluate the potential contribution of a two-dose vaccination strategy in Costa Rica.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Pediatrics, Hospital Nacional de Niños \"Dr. Carlos Sáenz Herrera\", Caja Costarricense de Seguro Social (CCSS), San Jose 10101, Costa Rica.",
    "Department of Pediatric Infectious Diseases, Hospital Nacional de Niños \"Dr. Carlos Sáenz Herrera\", Caja Costarricense de Seguro Social (CCSS), San Jose 10101, Costa Rica.",
    "Faculty of Medicine, Universidad de Ciencias Médicas (UCIMED), San Jose 10101, Costa Rica.",
    "Center for Infectious Disease Modeling and Analysis, Yale University School of Public Health, New Haven, CT 06520, USA."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 7,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Oscar Hidalgo-Mora",
      "orcid": "0000-0002-2974-0964"
    },
    {
      "affs": [
        1
      ],
      "name": "Helena Brenes-Chacón",
      "orcid": "0000-0002-2207-7450"
    },
    {
      "affs": [
        2
      ],
      "name": "Sebastián Ospina-Henao",
      "orcid": "0000-0002-1328-0609"
    },
    {
      "affs": [
        1
      ],
      "name": "Alejandra Soriano-Fallas"
    },
    {
      "affs": [
        2
      ],
      "name": "Gabriela Naranjo-Zúñiga"
    },
    {
      "affs": [
        0
      ],
      "name": "Gabriela Ivankovich-Escoto"
    },
    {
      "affs": [
        3
      ],
      "name": "María L Ávila-Agüero",
      "orcid": "0000-0002-1979-0431"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/d4t1gx2qr1h3f.bib",
  "cited_by": 0,
  "doi": "10.3390/vaccines14100909",
  "fulltext_url": "https://europepmc.org/articles/PMC13709432",
  "id": "d4t1gx2qr1h3f",
  "issns": [
    "2076-393X"
  ],
  "landing_url": "https://europepmc.org/article/MED/42931438",
  "language": "eng",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2713|Herpesvirus Infections and Treatments"
    ]
  ],
  "openalex": "W7213234424",
  "pdf_url": "https://europepmc.org/articles/PMC13709432?pdf=render",
  "pmcid": "PMC13709432",
  "pmid": "42931438",
  "published": "2026-10-19",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/d4t1gx2qr1h3f.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:01Z",
      "native_id": "MED:42931438",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42931438"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2713|Herpesvirus Infections and Treatments",
      "subfield": "epidemiology-public-health"
    }
  ],
  "title": "Persistent Varicella Transmission in a High-Coverage Single-Dose Vaccination Program: Costa Rica, 2015-2024.",
  "title_text": "Persistent Varicella Transmission in a High-Coverage Single-Dose Vaccination Program: Costa Rica, 2015-2024.",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:22:01Z",
  "url": "https://research.draconitic.com/paper/d4t1gx2qr1h3f",
  "venue": "Vaccines",
  "versions": []
}