The COVID-19 vaccination campaigns were met with a varying level of vaccine hesitancy in Europe. We analyzed the potential relationships between COVID-19 vaccine coverage in different countries of the European Economic Area and rates of infection, hospitalizations, admissions to intensive care units (ICU), and deaths during the autumn 2021 SARS-CoV-2 wave (September−December). Significant negative correlations between infection rates and the percentage of fully vaccinated individuals were found during September, October, and November, but not December. The loss of this protective effect in December is likely due to the emergence of the omicron (B.1.1.529) variant, better adapted to evade vaccine-induced humoral immunity. For every considered month, the negative linear associations between the vaccine coverage and mean number of hospitalizations (r= −0.61 to −0.88), the mean number of ICU admissions (r= −0.62 to −0.81), and death rate (r= −0.64 to −0.84) were observed. The results highlight that vaccines provided significant benefits during autumn 2021. The vaccination of unvaccinated individuals should remain the primary strategy to decrease the hospital overloads, severe consequences of COVID-19, and deaths.

There is evidence that vaccination against seasonal influenza can improve innate immune responses to COVID-19 and decrease disease severity. However, less is known about whether it could also impact the humoral immunity in SARS-CoV-2 infected patients. The present study aimed to compare the SARS-CoV-2 specific humoral responses (IgG antibodies against nucleocapsid; anti-N, receptor binding domain; anti-RBD, subunit S2; anti-S2, and envelope protein; anti-E) between non-hospitalized, COVID-19 unvaccinated, and mild COVID-19 convalescent patients who were and were not vaccinated against influenza during the 2019/2020 epidemic season (n = 489 and n = 292, respectively). The influenza-vaccinated group had significantly higher frequency and titers of anti-N antibodies (75 vs. 66%; mean 559 vs. 520 U/mL) and anti-RBD antibodies (85 vs. 76%; mean 580 vs. 540 U/mL). The prevalence and concentrations of anti-S2 and anti-E antibodies did not differ between groups (40–43%; mean 370–375 U/mL and 1.4–1.7%; mean 261–294 U/mL) and were significantly lower compared to those of anti-RBD and anti-N. In both groups, age, comorbidities, and gender did not affect the prevalence and concentrations of studied antibodies. The results indicate that influenza vaccination can improve serum antibody levels produced in response to SARS-CoV-2 infection.

How frequently autoantibodies against angiotensin‐converting enzyme 2 (ACE2) occur in patients infected by SARS‐CoV‐2 is understudied and limited to investigations on a small sample size. The presence of these antibodies may contribute to the long‐lasting effects of COVID‐19 observed in some individuals, particularly if IgG‐class antibodies would emerge in patients. This study assessed the prevalence of IgG autoantibodies against ACE2 in 1139 patients infected with SARS‐CoV‐2 and examined their relationship with severity, demographic characteristics, and status of vaccination against influenza. The overall prevalence of anti‐ACE IgG antibodies in our cohort was 1.5%. Most of these individuals were men (76.5%) and underwent mild COVID‐19, but some severe and asymptomatic cases were also observed. Patients with severe infection had twofold higher titers than mild and asymptomatic cases. Age, comorbidities, and influenza vaccination status were not related to antibody prevalence. The prevalence of IgG anti‐SARS‐CoV‐2 antibodies (against nucleocapsid protein and S2 subunit, but not against receptor‐binding domain) was higher in the subset with ACE2 autoantibodies. Further research is required to understand the potential spectrum and duration of effects of IgG autoantibodies against ACE2 in patients after SARS‐CoV‐2 infection, particularly concerning long COVID‐19.

This study aimed to compare the occurrence and nuisance of adverse events following administration of each COVID-19 vaccine dose between two groups: individuals given three doses of mRNA vaccine (homologous group, 3 × mRNA, n = 252) and those given two doses of adenoviral vector vaccine further boosted with mRNA vaccine (heterologous group, 2 × AZ + 1 × mRNA, n = 205). Although the studied groups differed significantly in the frequency and number of side effects after the first and second vaccine dose, no relevant differences were seen following the booster administration. Arm pain and fatigue were the most common effects, regardless of the vaccination group and vaccine dose. In the homologous group, female sex, lower BMI, and no history of regular influenza vaccination were associated with a higher frequency of side effects of a booster dose. In the heterologous group, the history of COVID-19 was associated with an increased number of side effects seen after a booster. In both groups, the number of side effects related to the first and second dose correlated with the number observed after administration of a booster dose. Individuals receiving a homologous booster reported a higher nuisance of side effects than the heterologous group. It was similar to the level reported after the second dose in both groups. The use of pharmaceuticals to counteract the side effects was more frequent after a first dose in the 2 × AZ + 1 × mRNA group, but higher after second dose in individuals receiving the 3 × mRNA vaccination scheme. The frequency of pharmaceutical use after a booster dose was similar in both groups (approx. 60%). Paracetamol was most frequently chosen, regardless of the group and vaccine dose. In addition, the vast majority of participants (93%) declared to accept future doses of the COVID-19 vaccine if their administration would be recommended. This study provides an overview of the response to homologous and heterologous mRNA vaccine booster dose that may be valuable in shaping accurate and honest communication with vaccinated individuals, especially in those regions which are yet to pursue booster strategies.

The vaccination campaigns brought hope to minimizing the coronavirus disease 2019 (COVID‐19) burden. However, the emergence of novel, highly transmissible Omicron lineage of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) and the waning of neutralizing antibodies a few months after vaccination has brought concerns over the vaccine efficacy. The present work analyzed the relationships between COVID‐19 vaccine coverage (completion of primary course and booster dose intake) in the European Economic Area and rates of infection, hospitalizations, admissions to intensive care units (ICU), and deaths during the Omicron wave in the first quarter of 2022 (January–April). As demonstrated, infection rates were not correlated to vaccine coverage in any considered month. For January and February, the rates of hospitalizations, intensive care unit (ICU) admissions, and death due to COVID‐19 were strongly negatively correlated ( r =− 0.54 to −0.82) with the percentage of individuals who completed initial vaccination protocol and the percentage of those who received a booster dose. However, in March and April, the percentage of the population with primary vaccination course correlated negatively only with ICU admissions ( r = −0.77 and −0.46, respectively). The uptake of boosters in March still remained in significant negative correlation with hospitalizations ( r = −0.45), ICU admissions ( r = −0.70) and deaths due to COVID‐19 ( r = −0.37), although in April these relationships were no longer observed. The percentage of individuals with confirmed SARS‐CoV‐2 infection did not correlate with the pandemic indices for any considered month. The study indicates that COVID‐19 vaccination, including booster administration, was beneficial in decreasing the overwhelming of healthcare systems during the Omicron wave, but novel vaccine strategies may be required in the long term to enhance the effectiveness and durability of vaccine‐induced protection during future waves of SARS‐CoV‐2 infections.

No abstract

No abstract

Introduction. Probiotics are live microorganisms which, administered in appropriate amounts, have a beneficial effect on human health. Food products that contain these microorganisms are known as natural probiotics. Probiotic food include the group of dairy products in which fermented milk products are majority. Objective. The aim of the study is to review current data and summarize knowledge on the effects of consumption of dairy probiotics on human health. The review also aims at discussing the potential of these health-supporting microorganisms as a prevention factor against civilization diseases. State of knowledge. Consumption of probiotic food, especially natural dairy probiotic food, may have a positive effect on health due to the presence of probiotic bacteria or by the presence of their metabolites (postbiotics) demonstrating bioactive effects. The intake of these products is associated with the improvement of parameters such as lipid profile, insulin sensitivity, cardiovascular risk parameters, or presents protective effect on bones. Studies show a correlation between the consumption of natural probiotics and reduction in duration of diarrhea or alleviation of the course of inflammatory bowel diseases. Conclusion. The influence of natural dairy probiotics consumption on the state of health has recently been broadly investigated. Regular consumption of these products has shown beneficial effect on gut microbiota and on a wide range of health parameters. However, further studies are necessary to draw a precise conclusion.