Cargando…

Vaccination and Clinical Severity: Is the Effectiveness of Contact Tracing and Case Isolation Hampered by Past Vaccination?

While contact tracing and case isolation are considered as the first choice of interventions against a smallpox bioterrorist event, their effectiveness under vaccination is questioned, because not only susceptibility of host and infectiousness of case but also the risk of severe clinical manifestati...

Descripción completa

Detalles Bibliográficos
Autores principales: Mizumoto, Kenji, Ejima, Keisuke, Yamamoto, Taro, Nishiura, Hiroshi
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3709287/
https://www.ncbi.nlm.nih.gov/pubmed/23446821
http://dx.doi.org/10.3390/ijerph10030816
_version_ 1782276727884480512
author Mizumoto, Kenji
Ejima, Keisuke
Yamamoto, Taro
Nishiura, Hiroshi
author_facet Mizumoto, Kenji
Ejima, Keisuke
Yamamoto, Taro
Nishiura, Hiroshi
author_sort Mizumoto, Kenji
collection PubMed
description While contact tracing and case isolation are considered as the first choice of interventions against a smallpox bioterrorist event, their effectiveness under vaccination is questioned, because not only susceptibility of host and infectiousness of case but also the risk of severe clinical manifestations among cases is known to be reduced by vaccine-induced immunity, thereby potentially delaying the diagnosis and increasing mobility among vaccinated cases. We employed a multi-type stochastic epidemic model, aiming to assess the feasibility of contact tracing and case isolation in a partially vaccinated population and identify data gaps. We computed four epidemiological outcome measures, i.e., (i) the threshold of a major epidemic under the interventions; (ii) the expected total number of cases; (iii) the probability of extinction, and (iv) the expected duration of an outbreak, demonstrating that all of these outcomes critically depend on the clinical impact of past vaccination on the diagnosis and movement of vaccinated cases. We discuss that, even in the absence of smallpox in the present day, one should consider the way to empirically quantify the delay in case detection and an increase in the frequency of contacts among previously vaccinated cases compared to unvaccinated during the early stage of an epidemic so that the feasibility of contact tracing and case isolation in a vaccinated population can be explicitly assessed.
format Online
Article
Text
id pubmed-3709287
institution National Center for Biotechnology Information
language English
publishDate 2013
publisher MDPI
record_format MEDLINE/PubMed
spelling pubmed-37092872013-07-12 Vaccination and Clinical Severity: Is the Effectiveness of Contact Tracing and Case Isolation Hampered by Past Vaccination? Mizumoto, Kenji Ejima, Keisuke Yamamoto, Taro Nishiura, Hiroshi Int J Environ Res Public Health Article While contact tracing and case isolation are considered as the first choice of interventions against a smallpox bioterrorist event, their effectiveness under vaccination is questioned, because not only susceptibility of host and infectiousness of case but also the risk of severe clinical manifestations among cases is known to be reduced by vaccine-induced immunity, thereby potentially delaying the diagnosis and increasing mobility among vaccinated cases. We employed a multi-type stochastic epidemic model, aiming to assess the feasibility of contact tracing and case isolation in a partially vaccinated population and identify data gaps. We computed four epidemiological outcome measures, i.e., (i) the threshold of a major epidemic under the interventions; (ii) the expected total number of cases; (iii) the probability of extinction, and (iv) the expected duration of an outbreak, demonstrating that all of these outcomes critically depend on the clinical impact of past vaccination on the diagnosis and movement of vaccinated cases. We discuss that, even in the absence of smallpox in the present day, one should consider the way to empirically quantify the delay in case detection and an increase in the frequency of contacts among previously vaccinated cases compared to unvaccinated during the early stage of an epidemic so that the feasibility of contact tracing and case isolation in a vaccinated population can be explicitly assessed. MDPI 2013-02-27 2013-03 /pmc/articles/PMC3709287/ /pubmed/23446821 http://dx.doi.org/10.3390/ijerph10030816 Text en © 2013 by the authors; licensee MDPI, Basel, Switzerland. http://creativecommons.org/licenses/by/3.0/ This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/3.0/).
spellingShingle Article
Mizumoto, Kenji
Ejima, Keisuke
Yamamoto, Taro
Nishiura, Hiroshi
Vaccination and Clinical Severity: Is the Effectiveness of Contact Tracing and Case Isolation Hampered by Past Vaccination?
title Vaccination and Clinical Severity: Is the Effectiveness of Contact Tracing and Case Isolation Hampered by Past Vaccination?
title_full Vaccination and Clinical Severity: Is the Effectiveness of Contact Tracing and Case Isolation Hampered by Past Vaccination?
title_fullStr Vaccination and Clinical Severity: Is the Effectiveness of Contact Tracing and Case Isolation Hampered by Past Vaccination?
title_full_unstemmed Vaccination and Clinical Severity: Is the Effectiveness of Contact Tracing and Case Isolation Hampered by Past Vaccination?
title_short Vaccination and Clinical Severity: Is the Effectiveness of Contact Tracing and Case Isolation Hampered by Past Vaccination?
title_sort vaccination and clinical severity: is the effectiveness of contact tracing and case isolation hampered by past vaccination?
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3709287/
https://www.ncbi.nlm.nih.gov/pubmed/23446821
http://dx.doi.org/10.3390/ijerph10030816
work_keys_str_mv AT mizumotokenji vaccinationandclinicalseverityistheeffectivenessofcontacttracingandcaseisolationhamperedbypastvaccination
AT ejimakeisuke vaccinationandclinicalseverityistheeffectivenessofcontacttracingandcaseisolationhamperedbypastvaccination
AT yamamototaro vaccinationandclinicalseverityistheeffectivenessofcontacttracingandcaseisolationhamperedbypastvaccination
AT nishiurahiroshi vaccinationandclinicalseverityistheeffectivenessofcontacttracingandcaseisolationhamperedbypastvaccination