COVID-19 optimal vaccination policies: A modeling study on efficacy, natural and vaccine-induced immunity responses

Manuel Adrian Acuña-Zegarra, Saúl Díaz-Infante*, David Baca-Carrasco, Daniel Olmos-Liceaga

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

About a year into the pandemic, COVID-19 accumulates more than two million deaths worldwide. Despite non-pharmaceutical interventions such as social distance, mask-wearing, and restrictive lockdown, the daily confirmed cases remain growing. Vaccine developments from Pfizer, Moderna, and Gamaleya Institute reach more than 90% efficacy and sustain the vaccination campaigns in multiple countries. However, natural and vaccine-induced immunity responses remain poorly understood. There are great expectations, but the new SARS-CoV-2 variants demand to inquire if the vaccines will be highly protective or induce permanent immunity. Further, in the first quarter of 2021, vaccine supply is scarce. Consequently, some countries that are applying the Pfizer vaccine will delay its second required dose. Likewise, logistic supply, economic and political implications impose a set of grand challenges to develop vaccination policies. Therefore, health decision-makers require tools to evaluate hypothetical scenarios and evaluate admissible responses. Following some of the WHO-SAGE recommendations, we formulate an optimal control problem with mixed constraints to describe vaccination schedules. Our solution identifies vaccination policies that minimize the burden of COVID-19 quantified by the number of disability-adjusted years of life lost. These optimal policies ensure the vaccination coverage of a prescribed population fraction in a given time horizon and preserve hospitalization occupancy below a risk level. We explore “via simulation” plausible scenarios regarding efficacy, coverage, vaccine-induced, and natural immunity. Our simulations suggest that response regarding vaccine-induced immunity and reinfection periods would play a dominant role in mitigating COVID-19.

Original languageEnglish
Article number108614
JournalMathematical Biosciences
Volume337
DOIs
StatePublished - Jul 2021

Bibliographical note

Funding Information:
The authors acknowledge support from grant DGAPA-PAPIIT IV100220 and the Laboratorio Nacional de Visualización Científica UNAM, Mexico . MAAZ acknowledges support from PRODEP Programme, Mexico (No. 511-6/2019-8291 ). DBC acknowledges support from PRODEP Programme, Mexico (No. 511-6/2019-8022 ). We thank Dr. Jorge X. Velasco-Hernandez for useful comments and discussions of this work. Finally, the authors would like to acknowledge the anonymous referees for their invaluable comments and insight to our work.

Funding Information:
The authors acknowledge support from grant DGAPA-PAPIIT IV100220 and the Laboratorio Nacional de Visualizaci?n Cient?fica UNAM, Mexico. MAAZ acknowledges support from PRODEP Programme, Mexico (No. 511-6/2019-8291). DBC acknowledges support from PRODEP Programme, Mexico (No. 511-6/2019-8022). We thank Dr. Jorge X. Velasco-Hernandez for useful comments and discussions of this work. Finally, the authors would like to acknowledge the anonymous referees for their invaluable comments and insight to our work.

Publisher Copyright:
© 2021 Elsevier Inc.

Keywords

  • COVID-19
  • DALYs
  • Natural immunity
  • Optimal control
  • Reinfection
  • Vaccination policy
  • Vaccine efficacy
  • Vaccine profile
  • Vaccine-induced immunity
  • WHO-SAGE

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