Immune response to SARS-CoV-2 and the risk of COVID-19 among different groups of healthcare workers
Authors: Fatkhutdinova Liliya M. , Badamshina Gulnara G. , Sizova Elena P. , Patyashina Marina A. , Stavropolskaya Lidiya V. , Gabidinova Gulnaz F. , Zalyalov Ramil R. 
Published: July 2021

Introduction. To date, issues related to the protection of medical workers from COVID-19 infection, including immunological protection, are of particular interest. The aim of the study was to explore seroprevalence of the IgG to SARS-CoV-2 N-protein in various groups of medical workers with the following assessment of the risk of COVID-19, depending on the seropositivity and occupational group. Materials and methods. The study of the strength of immunity to COVID-19 was carried out within the framework of the large-scale Rospotrebnadzor program to assess population immunity to the SARS-CoV-2 virus in the population of the Russian Federation, considering the protocol recommended by WHO, on the basis of the laboratories of the Center for Hygiene and Epidemiology in the Republic of Tatarstan. From the sample of the study conducted in the Republic of Tatarstan, medical workers (301) were selected without a history of a new coronavirus infection and with no clinical symptoms of this disease at the time of biomaterial sampling (June 2020); the absence of the transferred new coronavirus infection was verified by the Unified State Information System "Electronic Health of the Republic of Tatarstan". The comparison group included 52 employees belonging to the engineering and technical personnel and not employed in medical institutions who met the above inclusion criteria. In the aggregate, the observation group (medical workers and the comparison group) included 12.1% of the participants in the population study. Results. The rate of seropositivity was 36.5% in the control groups, 23.7% - in doctors, and 38.9% - in nurses. Compared to doctors, seroprevalence was higher in nurses. The employment of medical workers in temporary infectious diseases hospitals did not affect the production of the IgG to SARS-CoV-2 N-protein. A relatively low prevalence of seropositivity among doctors of temporary infectious diseases hospitals was revealed. The probability of seroconversion decreased with age and did not depend on gender or history of recent contacts with COVID-19 patients. The survival analysis showed that the probability of remaining healthy by the end of the follow-up was the lowest among doctors from medical and preventive institutions that did not serve as temporary infectious diseases hospitals. The risk of COVID-19 in seronegative individuals was higher, but without statistical significance. Conclusion. According to the data of immunological studies for the presence of IgG antibodies to the nucleocapsid protein of the SARS-CoV-2 virus, it was found that the prevalence of seroprevalence in nurses is significantly higher than that of doctors, nurses of medical and prophylactic organizations of young age have higher seroprevalence to the nucleocapsid protein of the SARS-CoV-2. According to prospective observation, it was revealed that doctors of medical and prophylactic organizations that are not classified as temporary infectious diseases hospitals have a higher risk of developing a symptomatic form of COVID-19, which may be due to both the insufficient effectiveness of anti-epidemic measures and the peculiarities of the immune response and approaches, used to evaluate it. In the current epidemic situation, the detection of IgG antibodies to the SARS-CoV-2 virus can be used to decide on the distribution of responsibilities among medical personnel.