Seroprevalence of SARS-CoV-2 antibodies in the county town of Slovakia - a pilot study from the Trencin city.

Slovakia is a country with only 5.45 million inhabitants. However, the past two years of the COVID-19 pandemic have shown huge inter-regional differences. These were represented by different numbers of diagnosed SARS-CoV-2 cases and the vaccination rates in the regions, as well as by the willingness of the inhabitants to comply with anti-pandemic measures or to undergo testing. The occurrence of such regional disparities provided a rational basis for monitoring the epidemic situation within smaller areas, e.g. at city level. Trencin is a medium-sized Slovak county town with about 55 000 inhabitants. The city administration gave its residents the opportunity to assess their current level of antibodies against the SARS-CoV-2 virus, and received an additional benefit in the form of data on the real epidemic situation in the city, which helped in further management of anti-pandemic measures. The primary aim of the study, conducted in January and February 2022, was to determine the levels of antibodies against the SARS-CoV-2 virus in the inhabitants of Trencin. The results showed that 75% of the study participants, representing the adult population of the city, had detectable IgG antibodies against the SARS-CoV-2 spike protein. Noteworthy, at the time of the study, 13% of the Trencin city population who were unaware of overcoming COVID-19 had specific antibodies against the virus. Furthermore, the antibody levels in recovered unvaccinated subjects increased not only with the severity of their COVID-19 symptoms, but also after multiple recoveries from the disease. On the other hand, the severity of side effects after vaccination did not influence the antibody levels. The results of the study are in line with the current view that hybrid immunity (vaccination plus SARS-CoV-2 infection in any order) offers greater protection than immunity elicited by vaccination or COVID-19 separately. Keywords: SARS-CoV-2 coronavirus; COVID-19; ELISA; seroprevalence; antibodies; vaccination.

Ferrate (VI), Fenton Reaction and Its Modification: An Effective Method of Removing SARS-CoV-2 RNA from Hospital Wastewater.

The outbreak of the coronavirus disease 2019 (COVID-19) raises questions about the effective inactivation of its causative agent, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in medical wastewater by disinfectants. For this reason, our study of wastewater from a selected hospital evaluated several different advanced oxidation methods (Fenton reaction and Fenton-like reaction and ferrate (VI)) capable of effectively removing SARS-CoV-2 RNA. The obtained results of all investigated oxidation processes, such as ferrates, Fenton reaction and its modifications achieved above 90% efficiency in degradation of SARS-CoV-2 RNA in model water. The efficiency of degradation of real SARS-CoV-2 from hospital wastewater declines in following order ferrate (VI) > Fenton reaction > Fenton-like reaction. Similarly, the decrease of chemical oxygen demand compared to effluent was observed. Therefore, all of these methods can be used as a replacement of chlorination at the wastewater effluent, which appeared to be insufficient in SARS-CoV-2 removal (60%), whereas using of ferrates showed efficiency of up to 99%.

Sorption of SARS-CoV-2 Virus Particles to the Surface of Microplastics Released during Washing Processes.

The research aims at washing processes as possible sources of microplastics, specifical microfibers in wastewater, and the behavior of the virus particles SARS-CoV-2 in wastewater after the washing process as well as their ability to sorb to the surface of microfibers, released from washing processes. The conclusions of the research point to the ability of the virus to attach to possible solid impurities such as textile fibers (microfibers) occurring in the sewer and to the ability of wash water to influence their possible occurrence in the sewer. The highest efficiency (more than 99%) of removal virus particles was after washing process, using liquid washing powder, and washing soda. These findings may gradually contribute to a better understanding of the behavior of the virus particles in the sewer.

Seroprevalence of SARS-CoV-2 IgG antibodies in the staff of the Slovak Academy of Sciences in response to COVID-19 and/or vaccination: situation in August 2021.

Cross-sectional seroprevalence study of SARS-CoV-2 IgG antibodies was accomplished in the Slovak Academy of Sciences to inform authorities of research institutions about the situation at their workplaces, to assess the risk of next exposure to SARS-CoV-2, and to guide decisions on institutional measures sustaining essential research in evolving epidemic situation. Study participants provided informed consent, anamnestic information, and self-collected dry blood spot samples that were analyzed by ELISA for SARS-CoV-2 S protein-specific IgG antibodies. Relative antibody levels detected in 1928 subjects showed seroprevalence of 84.13% and led to the following main findings consistent with the current knowledge: (1) mRNA-based vaccines induce better humoral response compared to adenovirus vaccines, (2) antibody levels reflect severity of COVID-19 symptoms, (3) post-COVID vaccination results in marked elevation of IgG levels particularly in asymptomatic and mild cases, (4) antibody levels decrease with increasing time elapsed from vaccination or COVID-19. In addition, data sorting to distinct research institutes and their clustering to three principal scientific sections of the Slovak Academy of Sciences revealed marked differences in seroprevalence, and allowed to identify workplaces with relatively high seropositivity and response rate that can potentially provide a safer working environment than those, where seroprevalence was low or unknown due to low participation. Thus, findings of this study can have direct implications on management decisions during the next pandemic development, with the necessity to keep in mind the phenomenon of time-dependent immunity waning and current spread of more contagious Delta variant of SARS-CoV-2. Keywords: SARS-CoV-2 coronavirus; COVID-19; spike protein; seroprevalence; antibodies; vaccination.