Immune Netw.  2022 Jun;22(3):e23. 10.4110/in.2022.22.e23.

Modeling Incorporating the SeverityReducing Long-term Immunity: Higher Viral Transmission Paradoxically Reduces Severe COVID-19 During Endemic Transition

  • 1Department of Mathematical Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
  • 2Biomedical Mathematics Group, Institute for Basic Science (IBS), Daejeon 34126, Korea
  • 3Laboratory of Immunology and Infectious Diseases, Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
  • 4Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul 02841, Korea
  • 5Department of Statistics, Kyungpook National University, Daegu 41566, Korea
  • 6Division of Fundamental Research on Public Agenda, National Institute for Mathematical Sciences, Daejeon 34047, Korea
  • 7Division of Big Data Science, Korea University, Sejong 30019, Korea
  • 8The Center for Viral Immunology, Korea Virus Research Institute, Institute for Basic Science (IBS), Daejeon 34126, Korea


Natural infection with severe acute respiratory syndrome-coronavirus-2 or vaccination induces virus-specific immunity protecting hosts from infection and severe disease. While the infection-preventing immunity gradually declines, the severity-reducing immunity is relatively well preserved. Here, based on the different longevity of these distinct immunities, we develop a mathematical model to estimate courses of endemic transition of coronavirus disease 2019 (COVID-19). Our analysis demonstrates that high viral transmission unexpectedly reduces the rates of progression to severe COVID-19 during the course of endemic transition despite increased numbers of infection cases. Our study also shows that high viral transmission amongst populations with high vaccination coverages paradoxically accelerates the endemic transition of COVID-19 with reduced numbers of severe cases. These results provide critical insights for driving public health policies in the era of ‘living with COVID-19.’


COVID-19; SARS-CoV-2; Immunity; Severity; Endemic transition
Full Text Links
  • IN
export Copy
  • Twitter
  • Facebook
Similar articles
Copyright © 2023 by Korean Association of Medical Journal Editors. All rights reserved.     E-mail: