The Lancet Regional Health. Europe (Apr 2021)

Infection and transmission of SARS-CoV-2 in London care homes reporting no cases or outbreaks of COVID-19: Prospective observational cohort study, England 2020

  • Anna Jeffery-Smith,
  • Kate Dun-Campbell,
  • Roshni Janarthanan,
  • Jonathan Fok,
  • Emma Crawley-Boevey,
  • Amoolya Vusirikala,
  • Elena Fernandez Ruiz De Olano,
  • Marina Sanchez Perez,
  • Suzanne Tang,
  • Thomas AJ Rowland,
  • Edward Wynne-Evans,
  • Anita Bell,
  • Bharat Patel,
  • Zahin Amin-Chowdhury,
  • Felicity Aiano,
  • Karthik Paranthaman,
  • Thomas Ma,
  • Maria Saavedra-Campos,
  • Joanna Ellis,
  • Angie Lackenby,
  • Heather Whitaker,
  • Richard Myers,
  • Katja Höschler,
  • Kevin Brown,
  • Mary E Ramsay,
  • Nandini Shetty,
  • J. Yimmy Chow,
  • Shamez Ladhani,
  • Maria Zambon

Journal volume & issue
Vol. 3
p. 100038

Abstract

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Background: Care homes have been disproportionately affected by the COVID-19 pandemic. We investigated the potential role of asymptomatic infection and silent transmission in London care homes that reported no cases of COVID-19 during the first wave of the pandemic. Methods: Five care homes with no cases and two care homes reporting a single case of COVID-19 (non-outbreak homes) were investigated with nasal swabbing for SARS-CoV-2 RT-PCR and serology for SARS-CoV-2 antibodies five weeks later. Whole genome sequencing (WGS) was performed on RT-PCR positive samples. Serology results were compared with those of six care homes with recognised outbreaks. Findings: Across seven non-outbreak homes, 718 (387 staff, 331 residents) individuals had a nasal swab and 651 (386 staff, 265 residents) had follow-up serology. Sixteen individuals (13 residents, 3 staff) in five care homes with no reported cases were RT-PCR positive (care home positivity rates, 0 to 7.6%) compared to 13 individuals (3.0 and 10.8% positivity) in two homes reporting a single case.Seropositivity across these seven homes varied between 10.7-56.5%, with four exceeding community seroprevalence in London (14.8%). Seropositivity rates for staff and residents correlated significantly (rs 0.84, [95% CI 0.51-0.95] p <0.001) across the 13 homes. WGS identified multiple introductions into some homes and silent transmission of a single lineage between staff and residents in one home. Interpretation: We found high rates of asymptomatic infection and transmission even in care homes with no COVID-19 cases. The higher seropositivity rates compared to RT-PCR positivity highlights the true extent of the silent outbreak. Funding: PHE

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