Study of the General Toxic Properties of the Vaccine CoviVac in Immature Rats

Relevance . During 2021 and early 2022, the prevalence of COVID-19 in the child population was 9.5%, the frequency of hospitalizations of children and adolescents increased, and fatal outcomes began to be recorded. And in 2022–2023, the proportion of children infected with COVID-19 increased to 18%. At the same time, vaccination remains the most effective way to protect against infection. Studying the safety of vaccines for the prevention of coronavirus infection is an urgent task. Objective of the study . To study the safety of a vaccine for the prevention of a new coronavirus infection in immature animals. Materials and methods . The study was conducted on Wistar rats (60 males and 52 females). During the study, the vaccine or placebo was administered four times with an interval of 2 weeks, in doses of 0.125; 0.25 or 0.5 ml / animal. The dynamics of body weight, animal behavior in the open field test, mass coefficients of internal organs, spermogram were assessed, and histological assessment of the reproductive system organs and the injection site was performed. Results and discussion . No toxic effect of the KoviVak vaccine on animal behavior was revealed, positive dynamics of body weight of experimental animals were recorded. When assessing toxicity in relation to the reproductive system, no effect of placebo or vaccine on spermogram parameters and histological structure of organs was revealed. No effect of placebo and KoviVak vaccine on mass coefficients of internal organs was revealed. Histological changes at the injection site recorded in animals receiving placebo and KoviVak vaccine are explained by the mechanism of action of aluminum hydroxide, which is part of the placebo and vaccine. Conclusion . The preclinical study on juvenile animals showed the safety of the KoviVak vaccine.