Background: The long-term consequences of COVID-19 infection are becoming increasingly evident in recent studies. This repeated cross-sectional study aimed to explore the long-term health and cognitive effects of COVID-19, focusing on how virus variants, vaccination, illness severity, and time since infection impact post-COVID-19 outcomes. Methods: We examined three cohorts of university students (N = 584) and used non-parametric methods to assess correlations of various health and cognitive variables with SARS-CoV-2 infection, COVID-19 severity, vaccination status, time since infection, time since vaccination, and virus variants. Results: Our results suggest that some health and cognitive impairments may persist, with some even appearing to progressively worsen-particularly fatigue in women and memory in men-up to four years post-infection. The data further indicate that the ancestral SARS-CoV-2 variant may have the most significant long-term impact, while the Omicron variant appears to have the least. Interestingly, the severity of the acute illness was not correlated with the variant of SARS-CoV-2. The analysis also revealed that individuals who contracted COVID-19 after vaccination had better health and cognitive outcomes compared to those infected before vaccination. Conclusions: Overall, our results indicate that even in young individuals who predominantly experienced only mild forms of the infection, a gradual decline in health and fitness can occur over a span of four years post-infection. Notably, some negative trends-at least in men-only began to stabilize or even reverse during the fourth year, whereas in women, these trends showed no such improvement. These findings suggest that the long-term public health impacts of COVID-19 may be more severe and affect a much broader population than is commonly assumed.

• Keywords
• SARS-CoV-2, cognition, long COVID, long-term effects, mental health,
• Publication type
• Journal Article MeSH

The gradual decrease in the prevalence of serious infectious diseases over the last century has been followed by increase in so called "modern" diseases, including allergies, chronic inflammatory conditions, psychiatric, and metabolic disorders. Between 2019 and 2022, public awareness of the threat of infectious diseases in humans was renewed by the global pandemic of a new type of a coronavirus, the SARS-COV-2. This public interest opened improved possibilities to test hypotheses on the factors associated with inter-individual variation in susceptibility to infectious and "modern" diseases. Based on the Hygiene hypothesis and Biodiversity hypothesis, we predicted that contacts with natural environment and wildlife in childhood and/or in adulthood can improve general health and decrease the risks of severe COVID-19 progression or prevalence of the "modern" diseases, namely the allergies. Here we report the results of an online, self-evaluating questionnaire survey conducted in the Czech Republic, where we contrasted selected health issues, and linked them to the living environment, including the level of contacts with biodiversity. In a sample of 1188 respondents, we revealed a significant association of time spent in nature or contacts with biodiversity with physical and mental health, or incidence of allergies. This is unlike the COVID-19 progression, which was related to age, physical health, smoking, allergies, and interaction of age with smoking, but not to contacts with the natural environmental diversity. Our findings regarding to physical and mental health and allergies are in agreement with the Biodiversity hypothesis of allergy and, linking human and environmental health, they urge for One Health approach application.

• Keywords
• Allergies, Biodiversity antigen richness, Civilization diseases, Contacts with nature, Infectious diseases, Wildlife,
• MeSH
• Hypersensitivity epidemiology   MeSH
• Biodiversity * MeSH
• COVID-19 * epidemiology   MeSH
• Adult MeSH
• Mental Health MeSH
• Middle Aged MeSH
• Humans MeSH
• Young Adult MeSH
• Pandemics MeSH
• Surveys and Questionnaires MeSH
• SARS-CoV-2 * isolation & purification   pathogenicity   MeSH
• Aged MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Young Adult MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic epidemiology   MeSH

COVID-19 affects a variety of organs and systems of the body including the central nervous system. Recent research has shown that COVID-19 survivors often experience neurological and psychiatric complications that can last for months after infection. We conducted a large Internet study using online tests to analyze the effects of SARS-CoV-2 infection, COVID-19 severity, and vaccination on health, intelligence, memory, and information processing precision and speed in a cohort of 4445 subjects. We found that both SARS-CoV-2 infection and COVID-19 severity were associated with negative impacts on patients' health. Furthermore, we observed a negative association between COVID-19 severity and cognitive performance. Younger participants had a higher likelihood of SARS-CoV-2 contraction, while the elderly had a higher likelihood of severe COVID-19 and vaccination. The association between age and COVID-19 severity was primarily mediated by older participants' impaired long-term health. Vaccination was positively associated with intelligence and the precision of information processing. However, the positive association between vaccination and intelligence was likely mediated by achieved education, which was itself strongly associated with the likelihood of being vaccinated.

• Keywords
• COVID-19, SARS-CoV-2, cognition, cognitive performance, long-term effects, mental health,
• Publication type
• Journal Article MeSH

The confirmed number of SARS-CoV-2 infections up to 18 October 2022 is 626 million worldwide, but information about factors affecting the probability of infection or a severe course of COVID-19 remains insufficient and often speculative. Only a small number of factors have been rigorously examined, mostly by retrospective or cross-sectional studies. We ran a preregistered study on 5164 Internet users who shared information with us about their exposure to 105 risk factors and reported being COVID-19 negative before the beginning of the fourth wave of COVID-19 in the Czech Republic. After the fourth wave, in which 709 (13.7%) of participants were infected, we used a partial Kendall test controlled for sex, age, and urbanization to compare the risk of infection and a severe course of the disease in subjects who initially did and did not report exposure to particular risk factors. After the correction for multiple tests, we identified 13 factors - including male sex, lower age, blood group B, and larger household size - that increased the risk of infection and 16 factors - including mask-wearing, borreliosis in the past, use of vitamin D supplements, or rooibos drinking - that decreased it. We also identified 23 factors that increased the risk of a severe course of COVID-19 and 12 factors that decreased the risk. This preregistered longitudinal study is of explorative nature. Therefore, although the observed effects were strong and remained highly significant even after correction for multiple tests, it will be necessary to confirm their existence in future independent studies.

• Keywords
• Borelia, COPD, Rh factor, SARS-CoV-2, autoimmunity, blood goups, cats, course, dogs, epidemiology, immunodeficiency, masks, risk factors, rooibos, tobacco smoking, use of sauna, vitamin D,
• Publication type
• Journal Article MeSH