Human response to live plague vaccine EV, Almaty region, Kazakhstan, 2014-2015

PLoS One. 2019 Jun 14;14(6):e0218366. doi: 10.1371/journal.pone.0218366. eCollection 2019.

Abstract

Background: In Kazakhstan, a live plague vaccine EV 76 NIIEG has been used for plague prophylaxis since the mid-1930s. Vaccination is administered yearly among people living in plague-enzootic areas. Similar practices are used in other former Soviet Union countries. Yet, to this day, the effectiveness period of the vaccine is unknown. It is also not clear how different factors can affect the effectiveness of the vaccine over time.

Methods: We surveyed changes in antibody levels specific for F1 antigens of Yersinia pestis among vaccinated people 4, 8, and 12 months post- vaccination. Blood samples were taken from the participants of the study for producing sera, which was later analyzed using indirect hemagglutination reaction with antigenic erythrocyte assay (micromethod) for identifying antibodies to F1 Y.pestis.

Results: In first-time-receivers of the plague vaccine, antibody titer reached the highest level of antibody that represents a conditionally protective titer after 4 months, dropped drastically after 8 months, and dropped again after 12 months. Similar results were obtained among those who have been vaccinated previously. However, in that group, the percentage of people with a level of antibody that represents a conditionally protective titer remained statistically significant even after 8 and 12 months.

Conclusion: Based on the results of this study, we recommend initiating vaccination campaigns for the medical and veterinary staff, as well as the general population four months prior to the springtime epizootics of plague among wild rodents.

Publication types

  • Historical Article
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Female
  • Geography
  • History, 21st Century
  • Humans
  • Kazakhstan / epidemiology
  • Male
  • Middle Aged
  • Odds Ratio
  • Plague / history
  • Plague / prevention & control*
  • Plague Vaccine / administration & dosage
  • Plague Vaccine / immunology*
  • Vaccination
  • Yersinia pestis / immunology*
  • Young Adult

Substances

  • Plague Vaccine

Grant support

The study was conducted under FELTP CDC/CAR, 2013-2015 (CDC Field Epidemiology and Laboratory Training Program) to ZS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.