PLoS ONE (Jan 2022)

Epidemiological, virological and serological investigation of a SARS-CoV-2 outbreak (Alpha variant) in a primary school: A prospective longitudinal study.

  • Elsa Lorthe,
  • Mathilde Bellon,
  • Grégoire Michielin,
  • Julie Berthelot,
  • María-Eugenia Zaballa,
  • Francesco Pennacchio,
  • Meriem Bekliz,
  • Florian Laubscher,
  • Fatemeh Arefi,
  • Javier Perez-Saez,
  • Andrew S Azman,
  • Arnaud G L'Huillier,
  • Klara M Posfay-Barbe,
  • Laurent Kaiser,
  • Idris Guessous,
  • Sebastian J Maerkl,
  • Isabella Eckerle,
  • Silvia Stringhini,
  • SEROCoV-Schools Study Group

DOI
https://doi.org/10.1371/journal.pone.0272663
Journal volume & issue
Vol. 17, no. 8
p. e0272663

Abstract

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ObjectivesTo report a prospective epidemiological, virological and serological investigation of a SARS-CoV-2 outbreak in a primary school.MethodsAs part of a longitudinal, prospective, school-based surveillance study, this investigation involved repeated testing of 73 pupils, 9 teachers, 13 non-teaching staff and 26 household members of participants who tested positive, with rapid antigen tests and/or RT-PCR (Day 0-2 and Day 5-7), serologies on dried capillary blood samples (Day 0-2 and Day 30), contact tracing interviews and SARS-CoV-2 whole genome sequencing.ResultsWe identified 20 children (aged 4 to 6 years from 4 school classes), 2 teachers and a total of 4 household members who were infected by the Alpha variant during this outbreak. Infection attack rates were between 11.8 and 62.0% among pupils from the 4 school classes, 22.2% among teachers and 0% among non-teaching staff. Secondary attack rate among household members was 15.4%. Symptoms were reported by 63% of infected children, 100% of teachers and 50% of household members. All analysed sequences but one showed 100% identity. Serological tests detected 8 seroconversions unidentified by SARS-CoV-2 virological tests.ConclusionsThis study confirmed child-to-child and child-to-adult SARS-CoV-2 transmission and introduction into households. Effective measures to limit transmission in schools have the potential to reduce the overall community circulation.