The COVID-19 pandemic proceeds in waves, with variable characteristics of the clinical picture resulting from the evolution of the SARS-CoV-2 virus. This study aimed to compare the epidemiological characteristics, symptomatology, and outcomes of the disease in patients hospitalized for COVID-19 during periods of different variants dominance. Comparing the periods of dominance of variants preceding the Delta variant, the Delta period was characterized by a higher share of hospitalized females, less frequent comorbidities among patients, and a different age distribution. The lowest need for oxygen therapy and mechanical ventilation was observed under Omicron dominance. The triad of classic COVID-19 symptoms, cough, fever, dyspnoea, and fatigue, were most prevalent during the Delta period, and significantly less common under the Omicron dominance. During the Omicron period, nearly twice as many patients as in the previous periods could be discharged from the hospital within 7 days; the overall 28-day mortality was significantly lower compared to that of the Delta period. It also did not differ between periods that were dominated by the BA.1 and BA.2 subvariants. The study indicates that the Omicron SARS-CoV-2 variant that dominated between January and June 2022 caused a disease which resembled the common cold, and was caused by seasonal alpha and beta-coronaviruses with a low pathogenicity for humans. However, one should note that this effect may not only have been related to biological features of the Omicron lineage, but may additionally have been driven by the increased levels of immunization through natural infections and vaccinations, for which we could not account for due to a lack of sufficient data.

Background The real-world effectiveness of molnupiravir (MOL) during the dominance of Omicron SARS-CoV-2 lineage is urgently needed since the available data relate to the period of circulation of other viral variants. Therefore, this study assessed the efficacy of MOL in patients hospitalized for COVID-19 in a real-world clinical practice during the wave of Omicron infections. Methods Among 11,822 patients hospitalized after 1 March 2020 and included in the SARSTer national database, 590 were treated between 1 January and 31 April 2022, a period of dominance of the Omicron SARS-CoV-2 variant. MOL was administered to 203 patients, whereas 387 did not receive any antiviral regimen. Both groups were similar in terms of sex, BMI and age allowing for direct comparisons. Results Patients who did not receive antiviral therapy significantly more often required the use of Dexamethasone and Baricitinib. Treatment with MOL resulted in a statistically significant reduction in mortality during the 28-day follow-up (9.9 vs. 16.3%), which was particularly evident in the population of patients over 80 years of age treated in the first 5 days of the disease (14.6 vs. 35.2%). MOL therapy did not affect the frequency of the need for mechanical ventilation, but patients treated with MOL required oxygen supplementation less frequently than those without antivirals (31.7 vs. 49.2%). The time of hospitalization did not differ between groups. Conclusions The use of molnupiravir in patients hospitalized for COVID-19 during the dominance of Omicron variant reduced mortality. This effect is particularly evident in patients over 80 years of age.

In our study, we documented, based on objective indicators, a milder course of COVID-19 in patients hospitalized during the wave of cases in the first half of 2022 during the dominance of the Omicron variant of SARS-CoV-2 compared to cases in the second half of 2021 dominated by the Delta variant. Additionally, during Omicron wave greater use of antiviral drugs and lower use of immunomodulators was observed.

Difficult-to-treat populations with chronic hepatitis C (CHC), in the era of interferon treatment, included patients with liver cirrhosis, kidney impairment, treatment-experienced individuals, and those coinfected with the human immunodeficiency virus. The current study aimed to determine whether, in the era of direct-acting antivirals (DAA), there are still patients that are difficult-to-treat. The study included all consecutive patients chronically infected with hepatitis C virus (HCV) who started interferon-free therapy between July 2015 and December 2020 in the Department of Infectious Diseases in Kielce. The analyzed real-world population consisted of 963 patients, and most of them were infected with genotype 1 (87.6%) with the predominance of subtype 1b and were treatment-naïve (78.8%). Liver cirrhosis was determined in 207 individuals (21.5%), of whom 82.6% were compensated. The overall sustained virologic response, after exclusion of non-virologic failures, was achieved in 98.4%. The univariable analysis demonstrated the significantly lower response rates in males, patients with liver cirrhosis, decompensation of hepatic function at baseline, documented esophageal varices, concomitant diabetes, body mass index ≥25, and previous ineffective antiviral treatment. Despite an overall very high effectiveness, some unfavorable factors, including male gender, genotype 3 infection, liver cirrhosis, and treatment experience, significantly reduce the chances for a virologic response were identified.

Accumulating evidence shows that SARS‐CoV‐2 can potentially trigger autoimmune processes, which can be responsible for the long‐term consequences of COVID‐19. Therefore, this paper aims to review the autoantibodies reported in COVID‐19 convalescents. Six main groups were distinguished: (i) autoantibodies against components of the immune system, (ii) autoantibodies against components of the cardiovascular system, (iii) thyroid autoantibodies, (iv) autoantibodies specific for rheumatoid diseases, (v) antibodies against G‐protein coupled receptors, and (vi) other autoantibodies. The evidence reviewed here clearly highlights that SARS‐CoV‐2 infection may induce humoral autoimmune responses. However, the available studies share number of limitations, such as: (1) the sole presence of autoantibodies does not necessarily implicate the clinically‐relevant risks, (2) functional investigations were rarely performed and it is often unknown whether observed autoantibodies are pathogenic, (3) the control seroprevalence, in healthy, noninfected individuals was often not reported; thus it is sometimes unknown whether the detected autoantibodies are the result of SARS‐CoV‐2 infection or the accidental post‐COVID‐19 detection, (4) the presence of autoantibodies was rarely correlated with symptoms of the post‐COVID‐19 syndrome, (5) the size of the studied groups were often small, (6) the studies focused predominantly on adult populations, (7) age‐ and sex‐related differences in seroprevalence of autoantibodies were rarely explored, (8) genetic predispositions that may be involved in generation of autoantibodies during SARS‐CoV‐2 infections were not investigated, and (9) the autoimmune reactions following infection with SARS‐CoV‐2 variants that vary in the clinical course of infection remain unexplored. Further longitudinal studies are advocated to assess the link between identified autoantibodies and particular clinical outcomes in COVID‐19 convalescents.