Imported Infections Versus Herd Immunity Gaps; A Didactic Demonstration of Compartment Models Through the Example of a Minor Measles Outbreak in Hungary

  • Katalin Böröcz* Department of Immunology and Biotechnology, Clinical Centre, University of Pécs Medical School, Pécs, Hungary
  • Ákos Markovics Department of General and Physical Chemistry , Faculty of Natural Sciences, University of Pécs, Pécs, Hungary
  • Zsuzsanna Csizmadia Department of Immunology and Biotechnology, Clinical Centre, University of Pécs Medical School, Pécs, Hungary
  • Joseph Najbauer Department of Immunology and Biotechnology, Clinical Centre, University of Pécs Medical School, Pécs, Hungary
  • Timea Berki Department of Immunology and Biotechnology, Clinical Centre, University of Pécs Medical School, Pécs, Hungary
  • Péter Németh Department of Immunology and Biotechnology, Clinical Centre, University of Pécs Medical School, Pécs, Hungary

Abstract

Introduction: In Hungary, where MMR vaccine coverage is 99%, in 2017, a minor measles epidemic started from imported cases due to two major factors – latent susceptible cohorts among the domestic population and the vicinity of measles-endemic countries. Suspended immunization activities due to the COVID-19 surge are an ominous precursor to a measles resurgence.  This epidemiological demonstration is aimed at promoting a better public understanding of epidemiological data.


Materials and Methods: Our previous MMR sero-epidemiological measurements (N of total measles cases = 3919, N of mumps cases = 2132, and N of rubella cases = 2132) were analyzed using open-source epidemiological data (ANTSZ) of a small-scale measles epidemic outbreak (2017, Hungary). A simplified SEIR model was applied in the analysis.


Results: In case of measles, due to a cluster-specific inadequacy of IgG levels, the cumulative seropositivity ratios (measles = 89.97%) failed to reach the herd immunity threshold (HIT Measles = 92–95%). Despite the fact that 90% of overall vaccination coverage is just slightly below the HIT, unprotected individuals may pose an elevated epidemiological risk. According to the SEIR model, ≥74% of susceptible individuals are expected to get infected. Estimations based on the input data of a local epidemic may suggest an even lower effective coverage rate (80%) in certain clusters of the population.


Conclusion: Serological survey-based, historical and model-computed results are in agreement. A practical demonstration of epidemiological events of the past and present may promote a higher awareness of infectious diseases. Because of the high R0 value of measles, continuous large-scale monitoring of humoral immunity levels is important.

Published
Apr 28, 2021
How to Cite
BÖRÖCZ*, Katalin et al. Imported Infections Versus Herd Immunity Gaps; A Didactic Demonstration of Compartment Models Through the Example of a Minor Measles Outbreak in Hungary. Southeastern European Medical Journal, [S.l.], v. 5, n. 1, p. 1-16, apr. 2021. ISSN 2459-9484. Available at: <http://seemedj.mefos.unios.hr/index.php/seemedj/article/view/199>. Date accessed: 03 aug. 2021. doi: http://dx.doi.org/10.26332/seemedj.v5i1.199.
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Articles