Diphtheria in the Kazakh SSR in 1958–1961: Epidemiological Dynamics and Initial Results of Mass Immunisation

Abstract

The article examinesthe change in the epidemiological situation in the Kazakh SSR at theturn of the 1950s and 1960s, considering the shift towards the mass immunisation of children. The objective of the study is to identify the rates, territorial characteristics and factors of the dynamics of incidence in 1958 –1961, as well as to evaluate the initial results of the vaccination program. The source base consisted of archival reports and statistical documents from health authorities and the sanitary-epidemiological service. These documents contained information on regions, urban and rural areas, age groups, vaccination status, disease focality, clinical forms, laboratory confirmation and disease outcomes. The comparative-historical, problemchronological and statistical methods were employed. The material was analysed using the endogenousprimary approach, which links epidemiological results with the internal capabilities of the republican healthcare system. The scientific novelty lies in the comprehensive introduction of little-studied statistical tables to research circulation, which made it possible to reconstruct regional processes that were not reflected in All-Union or average republic dynamics. A review of the evidence suggests that the situation remained tense at the end of the 1950s. Following a decline in the number of patients, 10,733 cases were registered in 1959. In 1960, their number decreased to 7,500, and in 1961 it was approximately half that of the previous period. However, it should be noted that the positive dynamics were not synchronous: in 1959–1960, growth continued in some areas, while the directions of change in cities and rural areas often differed. Despite the overall decline in 1961, cases in several territories continued to exceed the national average. A comparison of age and vaccination data confirmed the protective effect of vaccination but showed that nominal coverage alone was not sufficient for protection. The diseases observed in vaccinated and revaccinated children required consideration of the completeness of the vaccination course, the timing of the revaccination and the quality of the vaccines. Continued active transmission of the infection was indicated by cases in organised groups, multiple focal spots and registered outbreaks. It was concluded that mass immunisation was a decisive factor in the epidemiological shift. However, its impact was gradual and uneven across different territories. By 1961, the Republic had entered a period of steady decline in disease incidence, though it had not yet achieved full control of the infection. The effectiveness of the campaign was determined by a combination of factors, including vaccination coverage, organisational quality, laboratory surveillance, early diagnosis, hospitalisation and timely treatment.