Epidemiological traits of measles in infectious hospital staff

Abstract

The maximum incidence rates of measles were recorded on the eve of the development of the COVID-19 pandemic in 2019 in many countries of the world, including Russia. One of the features of the epidemic process of this infection in the period from 2011 to 2019 was the involvement of employees of medical organizations (MO) with the formation of large foci. Current features for the development of the measles epidemic situation can be assessed using serological studies. Aim: to assess the epidemiological features of measles in medical workers in Moscow, including by assessing the prevalence of specific IgG antibodies to the measles virus using the example of an infectious disease’s hospital in Moscow. Materials and methods. Using data from state reports on the sanitary and epidemiological well-being of the population in Moscow and form No. 2 of the Federal State Statistical Observation «Information on Infectious and Parasitic Diseases». To study the strength of immunity against measles by the method of enzyme-linked immunosorbent assay (ELISA) using test systems «Vecto-measles IgG» (CJSC «Vector-Best», Russia), 191 blood serum samples from the collection of the Department of Epidemiology of the National Research Center for Epidemiology were examined and Microbiology named after Honorary Academician N. F. Gamaleya (Moscow), taken from the employees of the infectious hospital of the city of Moscow (aged 22 to 65 years) with a different vaccination history. Positive (seropositive) was considered the result of a study of the level of IgG antibodies to measles virus more than 0.18 IU / ml. Results. A feature of the epidemic process of measles in Moscow (for the period from 2014 to 2020) was the annual (except for 2016) registration of measles cases among medical workers and hospital patients of various profiles (in 2019–2020, only among patients). Reasonable doubts about the reliability of the vaccination coverage of the population according to official statistics (exceeds the level of 95 % since 2013), including medical workers, arise due to the availability of data on the previous vaccination in some cases of measles. Measles vaccination data were recorded in 28 people (4.7 %) out of 191 surveyed. In two of them, antibodies to the measles virus could not be detected, and the median of their level in seropositive individuals was 1.75 IU / ml (0.5; 3.0). 10 health workers had a history of measles in the past, which was confirmed by serological examination (the level of IgG antibodies was higher than 3.3 IU / ml). 152 people (79.6 %) had no information about vaccination and measles in the past. Among them, eight people were seronegative (5.3 %), and the level of antibodies in the seropositive was higher than in the vaccinated, and amounted to 2.4 IU / ml [0.74; 3.68]. Conclusion. It was found that the proportion of seronegative among the surveyed individuals did not exceed 7 %. However, the predominance of individuals with a low level of immunity, both among vaccinated and unvaccinated individuals, indicates the need for periodic serological studies for the timely detection of seronegative individuals.