Modelling of Waning of Immunity and Reinfection Induced Antibody Boosting of SARS-CoV-2 in Manaus, Brazil

Haozhen Wei, Salihu S. Musa, Yanji Zhao, Daihai He

Research output: Journal article publicationJournal articleAcademic researchpeer-review

2 Citations (Scopus)


It was reported that the Brazilian city, Manaus, likely exceeded the herd immunity thresh-old (presumably 60–70%) in November 2020 after the first wave of COVID-19, based on the serological data of a routine blood donor. However, a second wave started in November 2020, when an even higher magnitude of deaths hit the city. The arrival of the second wave coincided with the emergence of the Gamma (P.1) variant of SARS-CoV-2, with higher transmissibility, a younger age profile of cases, and a higher hospitalization rate. Prete et al. (2020 MedRxiv 21256644) found that 8 to 33 of 238 (3.4–13.9%) repeated blood donors likely were infected twice in Manaus between March 2020 and March 2021. It is unclear how this finding can be used to explain the second wave. We propose a simple model which allows reinfection to explain the two-wave pattern in Manaus. We find that the two waves with 30% and 40% infection attack rates, respectively, and a reinfection ratio at 3.4–13.9%, can explain the two waves well. We argue that the second wave was likely because the city had not exceeded the herd immunity level after the first wave. The reinfection likely played a weak role in causing the two waves.

Original languageEnglish
Article number1729
Pages (from-to)1-7
Number of pages7
JournalInternational Journal of Environmental Research and Public Health
Issue number3
Publication statusPublished - 1 Feb 2022


  • Boosting of immunity
  • COVID-19
  • Reinfection
  • Waning of immunity

ASJC Scopus subject areas

  • Pollution
  • Public Health, Environmental and Occupational Health
  • Health, Toxicology and Mutagenesis


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