Abstract
BackgroundIn 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.MethodsWe 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.ResultsIn 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.ConclusionBased 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.
Highlights
IntroductionIt is not surprising that one of the first attempts to create a vaccine was an attempt to develop a vaccine against the plague
Since plague has taken many human lives in the past
In Kazakhstan, a live plague vaccine EV 76 NIIEG has been used for plague prophylaxis since the mid-1930s
Summary
It is not surprising that one of the first attempts to create a vaccine was an attempt to develop a vaccine against the plague. The first effective plague vaccine was created by The Institut Pasteur in late 1890s. Two types of plague vaccines are used globally: killed-whole cell (KWC) and live whole-cell (LWC). KWC vaccines use virulent strains killed by heating or adding formaldehyde, whereas LWC vaccines are created on the basis of virulent Y. pestis strains [2, 3, 4, 5,6]. Similar practices are used in other former Soviet Union countries To this day, the effectiveness period of the vaccine is unknown. It is not clear how different factors can affect the effectiveness of the vaccine over time
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