Vaccination against flu in the second and third trimesters of pregnancy with the use of Agrippal S1 is effective and meets the CPMP criteria. In our study, one month after vaccination, there was progress in the production of post-vaccination antibodies in protective values in pregnant women vaccinated in the third trimester of gestation. In neonates whose mothers had been vaccinated in the last trimester of pregnancy, there were also higher levels of protective antibodies to the flu A virus strains. Three months after childbirth, there were no significant differences in protective values of antibodies to all the strains of the flu virus in women of the compared groups. At the same time, in children born to women vaccinated in the third trimester of pregnancy, there was a significantly higher concentration of protective antibodies during the same period.

The aims of the study were to examine age-related features of immune response to measles virus in staff of a large city hospital and to define groups at risk for measles outbreaks.Methods. The study involved 1,855 staff members of a large city hospital aged ≥ 19 years old who had documented vaccination against measles or a history of measles. The participants were divided into age groups with 5-year intervals starting from 19 years of age; there were 11 groups in total. The immune response to measles virus was measured in sera by ELISA using Vector-Best IgG-Kor test system (Russia).Results. Young employers of 19 to 23 years of age were most susceptible to measles; protective antibody level was not detected in 38.5% of them. They were followed by young-to-middle-aged workers (24 to 48 years old) who were negative for anti-measles antibodies or had non-protective level of antibodies in 16.7% to 27.5%. The anti-measles antibody level was low (42.3 % to 60.0 %) in employers of 19 to 43 years of age and gradually increased to 46.3% – 92.2% in the group of 44 to 68 years old.Conclusion. Herd immunity against measles in employers of a large city hospital did not meet requirements for successful infection control which implicates ≤ 7% of seronegative individuals. This means that measles outbreak could occur at any time because the proportion of seronegative individuals (11.5%) twice exceeded the cut-off value; the antibody level was controversial in 3.2% of individuals. Therefore, monitoring anti-measles antibody level in hospital staff is necessary to detect groups at risk who should be vaccinated against measles.

It has been proven that post-vaccination immunity to measles virus after two doses of vaccine is not able to persistently protect against infection throughout life. The goal of this research was to determine the immune layer to the measles virus among women in labor and maternity ward personnel in the same medical institution. The levels of IgG antibodies to measles virus in the umbilical cord blood of 594 women in labor and 88 workers of the maternity ward were studied by ELISA. It was revealed that 22.7% of umbilical cord blood serum samples from parturient women and 21.4% of blood serum samples from maternity ward personnel were seronegative (<0.18 IU/ml). Levels of IgG antibodies to measles virus in low values (<1.0 IU/ml) were detected in 67% of blood serum samples among women in labor and 68.9% among employees of the maternity ward. Among women in labor, women under 35 years of age are at the highest risk of contracting measles; the proportion of women with low levels of protective antibodies in this age group was almost 70%, and the proportion of women without protective levels of antibodies was 23%. Compared with the age group 36–43, the age of women in labor under 35 was associated with a higher chance of not having immune protection against infection with measles virus OR [95% CI] = 2.2 [1.1–4.5] (p = 0.02) or had a low level of protection OR [95% CI] = 1.9 [1.2–3.0] (p = 0.001). It was also found that among women over 35 years of age, the proportion of persons with a high level of antibodies in women in labor was statistically significantly higher than among members of the maternity ward staff (13 and 0%, respectively, p = 0.007). Thus, maternity ward employees and women in labor constitute a risk group for measles due to the presence of a high proportion of seronegative persons among women of childbearing age (both maternity ward employees and women in labor). These conditions create the need to revise current approaches to present vaccination procedures, especially in the current epidemiological situation with COVID-19.

Within a framework of the state measles elimination program, in April, 2018 a level of measles herd immunity was assessed in 1899 Moscow hospital medical workers aged from 19 to 69 years and older. All subjects enrolled in the study were vaccinated against measles or recovered after measles infection. Serum samples were collected from subjects and examined by ELISA for measles IgG antibodies with the Vector-Best IgG-measle test system (Russia). It was found that 278 (14.6%) and 1621 (85.4%) subjects were seronegative (< 0.18 IU/mL) and seropositive (> 0.18 IU/ml), respectively. Age-related group distribution of 1855 serum samples revealed that percentage of seronegative subjects was in: aged 19—23 years was -38.5%; 24-28 and 29-33 years - 22.2%; 34-38 years - 27.5%; 39-43 years - 25.8%; 44-48 years - 16.8%; 49-53 and 54-58 years — 8.6% and 8.3%, respectively; 59-63 years old — 4.9%; 64-68 and over 69 years old — 0%. Moreover, mean level of measles IgG antibodies increased proportionally to age of medical workers from 0.58 IU/ml (19-23 years) to 2.94-2.72 IU/ml (64-68 and over 69 years). The data obtained indicate that a cohort of measles susceptible subjects (from 38.5% to 16.8%), respectively, is identified among young and middle age (from 19 to 48 years) individuals. It is assumed that two-dose measles vaccination in childhood does not contribute to the long-term preservation of protective levels of measles antibodies, thereby justifying a need to administer a three-dose measles vaccine.

Aim. Determination of intensity of immunity against measles in patients on waiting-list for lung transplantation. Materials and methods. IgG levels against measles virus were studied in blood sera of 80 adult patients (mean age 35.8± 11.4 years) on waiting-list of lung transplantation, without history of this disease. Determination of IgG levels against measles virus was carried out by ELISA using a standard kit from «Vektor-Best» (VectoMeasles-IgG). Results. Protective level of IgG against measles virus (above 0.18 I U/ml) was registered in 83.3% of examined patients. Mean level of anti-measles antibodies was within protective values - 1.53 IU/ml (95% confidence interval 1.17 - 1.89). Medium level of anti-measles antibodies (1 - 5 IU/ml) was registered in most of the analyzed samples (55.2%). A positive correlation between values of antibodies and age of patients (r=0.43) was detected. Dependence between levels of antibodies and previously executed hormonal and cytostatic therapy was not detected. Conclusion. Patients on waiting-list of solid organ transplantation are a group of risk for development of severe course of measles infection, that dictates the necessity of execution of vaccination at short terms before or after registration on the waiting-list.