{
  "abstract": "BackgroundRespiratory syncytial virus (RSV) remains a leading cause of hospitalization in infancy, with severe outcomes influenced by both contact patterns and passive immunity. Non-pharmaceutical interventions (NPIs) during the COVID-19 pandemic suppressed RSV circulation and reduced opportunities for maternal immune boosting, potentially altering protection among newborns. We evaluated whether incorporating time-varying maternal immunity improves the ability of an age-structured transmission model to predict post-pandemic RSV hospitalization patterns in infants.\n\nMethodsWe analyzed population-based RSV hospitalizations among Ontario (Canada) infants (<1 year) from July 2, 2017 to June 25, 2024, using linked administrative databases. A deterministic compartmental model across seven age classes was calibrated against pre-pandemic data using Latin Hypercube Sampling. We compared a model incorporating time-varying contact rates alone against a specification that additionally included time-varying maternal immunity.\n\nResultsBoth specifications accurately reproduced pre-pandemic seasonality and macro-level post-pandemic resurgence features. The constant maternal immunity model showed slightly better accuracy in capturing the 2021/22 peak compared to the time-varying maternal immunity specification. However, both qualitatively captured the continued near-absence of RSV and the observed peak was captured within the 95% credible intervals. While both models precisely captured the timing and overwhelming surge of admissions that occurred in 2022/23, they failed to capture the premature peak timing and magnitude in 2023/24.\n\nConclusionsIncorporating time-varying maternal immunity did not improve model accuracy post-pandemic. While maternal protection is essential for evaluating infant immunizations, population-level contact shifts primarily shaped post-pandemic RSV seasonality, indicating that models must account for these mechanisms of RSV transmission dynamics.\n\nSummaryUsing population-based Ontario hospitalization data, we evaluated whether incorporating time-varying maternal immunity improves an age-structured transmission model s ability to reproduce infant RSV disease patterns. While maternal immunity did impact post-pandemic RSV resurgences, we found that population-level contact pattern shifts were primarily responsible.",
  "abstract_shown": true,
  "affiliations": [
    "Public Health Ontario"
  ],
  "article_type": "PUBLISHAHEADOFPRINT",
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "name": "A. Parpia"
    },
    {
      "name": "J. Wright"
    },
    {
      "name": "A. Gharouni"
    },
    {
      "name": "N. Thampi"
    },
    {
      "affs": [
        0
      ],
      "name": "T. Fitzpatrick"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/b17d26v9hee2c.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.08.28.26361657",
  "fulltext_url": "https://www.medrxiv.org/content/10.64898/2026.08.28.26361657v1.full",
  "id": "b17d26v9hee2c",
  "issns": [],
  "landing_url": "https://www.medrxiv.org/content/10.64898/2026.08.28.26361657v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "medrxiv",
      "epidemiology"
    ],
    [
      "openalex",
      "2713|Respiratory viral infections research"
    ]
  ],
  "openalex": "W7204808068",
  "pdf_url": "https://www.medrxiv.org/content/10.64898/2026.08.28.26361657v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-28",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/b17d26v9hee2c.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:24Z",
      "native_id": "10.64898/2026.08.28.26361657",
      "source": "medrxiv",
      "url": "https://www.medrxiv.org/content/10.64898/2026.08.28.26361657v2"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "medrxiv:epidemiology",
      "subfield": "epidemiology-public-health"
    }
  ],
  "title": "Understanding RSV Resurgence Following COVID-19 in Ontario, Canada: Evaluating the Roles of Contact Patterns and Maternal Immunity",
  "title_text": "Understanding RSV Resurgence Following COVID-19 in Ontario, Canada: Evaluating the Roles of Contact Patterns and Maternal Immunity",
  "type": "preprint",
  "updated_at": "2026-10-30T12:18:03Z",
  "url": "https://research.draconitic.com/paper/b17d26v9hee2c",
  "venue": "medRxiv",
  "versions": []
}