«Оценка возрастной структуры больных корью c первичным и вторичным иммунным ответом за период 2010-2016 годы в Российской Федерации.

The blood serum samples of 5539 patients aged < 1 - 60 years with clinically and laboratory confirmed measles for the period of 2010-2016 were studied. The type of immune response was determined for all measles cases – primary or secondary. Studies included children aged <1 -14 years (2381), adolescents 15-17 years old (189) and adults 18-60 years old (2969). The specific activity of IgM antibodies in sera was determined by ELISA test systems "VektoKor’ IgM" (Russia), the concentration and avidity of specific IgG – by “Anti-Measles Viruses ELISA / IgG” and “Avidity: Anti-Measles Viruses ELISA / IgG” (EUROIMMUN, Germany). The interpretation of primary immune response was based on the presence of the serum specific IgM and IgG of low avidity. Secondary immune response was characterized by positive IgM result and IgG of high avidity in concentration of ≥5.0 IU / ml. The results of IgM testing demonstrated that in 2010-2016 the measles incidence was mainly supported by children aged 1-2 years - 39.9% of the total number of children with measles <1 - 14 years old and adults 18-40 years old - 80.1% of the total number of patients 15-60 years old.The serum specific IgG testing showed that in 15.0% of cases the IgG antibodies were detected at a concentration of ≥5.0 IU / ml. The additional dilution of sera resulted in the IgG titer values in the range of 8.5 - 45.0 IU / ml (21.4 ± 0.36) with a high degree of avidity: 80-100% (92.5 ± 0.2). In the rest 85.0% of cases IgG in sera of measles patients had a low degree of avidity (<30%) with a concentration of 0.2 - 3.46 IU / ml (1.73 ± 0.03). An age-based analysis of the results obtained demonstrated that all children under 14 years of age with laboratory confirmed measles had a primary immune response. The part of measles patients aged 15-60 with a primary immune response for whom measles could have been prevented by timely vaccination consisted 73.7%; persons with “vaccine failures” - 26.3%. The percentage of patients with “vaccine failures” in the years of relative epidemic well-being in 2010 (0.09 per 100 thousand people) and 2016 (0.12 per 100 thousand people) was 35.3% and 18.2% accordingly, exceeding 9.9% (p <0.001) - an indicator of the period of high incidence in 2014 (3.24 per 100 thousand people).The obtained results indicate the measles virus circulation among people with “vaccine failures,” which may be the potential for the spread and infection of unprotected populations and cause measles outbreaks during the period of epidemic well-being.