Dynamics of SARS-CoV-2 Major Genetic Lineages in Moscow in the Context of Vaccine Prophylaxis.

Findings collected over two and a half years of the COVID-19 pandemic demonstrated that the level immunity resulting from vaccination and infection is insufficient to stop the circulation of new genetic variants. The short-term decline in morbidity was followed by a steady increase. The early identification of new genetic lineages that will require vaccine adaptation in the future is an important research target. In this study, we summarised data on the variability of genetic line composition throughout the COVID-19 pandemic in Moscow, Russia, and evaluated the virological and epidemiological features of dominant variants in the context of selected vaccine prophylaxes. The prevalence of the Omicron variant highlighted the low effectiveness of the existing immune layer in preventing infection, which points to the necessity of optimising the antigens used in vaccines in Moscow. Logistic growth curves showing the rate at which the new variant displaces the previously dominant variants may serve as early indicators for selecting candidates for updated vaccines, along with estimates of efficacy, reduced viral neutralising activity against the new strains, and viral load in previously vaccinated patients.

Sputnik V Effectiveness against Hospitalization with COVID-19 during Omicron Dominance.

Mass vaccination campaigns against COVID-19 affected more than 90% of the population in most developed countries. The new epidemiologic wave of COVID-19 has been ongoing since the end of 2021. It is caused by a virus variant B.1.1.529, also known as "Omicron" and its descendants. The effectiveness of major vaccines against Omicron is not known. The purpose of this study is to evaluate the efficacy of the Sputnik V vaccine. The main goal is to assess its protection against hospitalization in the period of Omicron dominance. We conducted our study based on a large clinical center in Moscow (Russia) where 1112 patients were included. We used the case-population method to perform the calculations. The data we obtained indicate that the Omicron variant causes at least 90% of infections in the studied cohort. The effectiveness of protection against hospitalization with COVID-19 in our study was 85.9% (95% CI 83.0-88.0%) for those who received more than one dose. It was 87.6% (95% CI 85.4-89.5%) and 97.0% (95% CI 95.9-97.8%) for those who received more than two or three doses. The effectiveness in cases of more severe forms was higher than for less severe ones. Thus, present study indicates the high protective efficacy of vaccination against hospitalization with COVID-19 in case of Omicron lineage.