Prevalence of circulating antibodies against hemagglutinin of influenza viruses in epidemic season 2021/2022 in Poland.

The aim of the study was to determine the level of anti-hemagglutinin antibodies in the serum of patients during the 2021/2022 epidemic season in Poland. A total of 700 sera samples were tested, divided according to the age of the patients into 7 age groups: 0-4 years of age, 5-9 years of age, 10-14 years of age, 15-25 years of age, 26-44 years of age, 45-64 years of age and ≥65 years of age, 100 samples were collected from each age group. Anti-hemagglutinin antibody levels was determined using the haemagglutination inhibition assay (OZHA). The results obtained confirm the presence of anti-hemagglutinin antibodies for the antigens A/Victoria/2570/2019 (H1N1) pdm09, A/Cambodia/e0826360/2020 (H3N2), B/Washington/02/2019 and B/Phuket/3073/2013 recommended by World Health Organization (WHO) for the 2021/2022 epidemic season. The analysis of the results shows differences in the levels of individual anti-hemagglutinin antibodies in the considered age groups. In view of very low percentage of the vaccinated population in Poland, which was 6.90% in the 2021/2022 epidemic season, the results obtained in the study would have to be interpreted as the immune system response in patients after a previous influenza virus infection.

Molecular Determinants of Drug Resistance and Mutation Patterns in Influenza Viruses Circulating in Poland Across Multiple Epidemic Seasons: Implications for Vaccination Strategies.

BACKGROUND According to the WHO, up to 650 000 people die each year from seasonal flu-related respiratory illnesses. The most effective method of fighting the virus is seasonal vaccination. However, if an infection does occur, antiviral medications should be used as soon as possible. No studies of drug resistance in influenza viruses circulating in Poland have been systematically conducted. Therefore, the aim of the present study was to investigate the drug resistance and genetic diversity of influenza virus strains circulating in Poland by determining the presence of mutations in the neuraminidase gene. MATERIAL AND METHODS A total of 258 clinical specimens were collected during the 2016-2017, 2017-2018, and 2018-2019 epidemic seasons. The samples containing influenza A and B were analyzed by RT-PCR and Sanger sequencing. RESULTS Differences were found between the influenza virus strains detected in different epidemic seasons, demonstrating the occurrence of mutations. Influenza A virus was found to be more genetically variable than influenza B virus (P<0.001, Kruskal-Wallis test). However, there was no significant difference in the resistance prevalence between the influenza A subtypes A/H1N1/pdm09 (4.8%) and A/H3N2/ (6.1%). In contrast, more mutations of drug-resistance genes were found in the influenza B virus (P<0.001, chi-square test). In addition, resistance mutations appeared en masse in vaccine strains circulating in unvaccinated populations. CONCLUSIONS It seems important to determine whether the influenza virus strains tested for drug resistance as part of global influenza surveillance are equally representative of viruses circulating in populations with high and low vaccination rates, for all countries. Our results suggest that countries with low levels of influenza immunization may constitute reservoirs of drug-resistant influenza viruses.

Influenza and Influenza-Like Virus Infection in Children Under 14 Years of Age: An Investigation of 725 Cases in the 2021/2022 Influenza Epidemic Season in Poland.

BACKGROUND Influenza in children poses a significant health problem worldwide. In this study we investigated 725 cases of influenza and influenza-like virus infection in children under 14 years of age in the 2021/2022 influenza epidemic season in Poland. MATERIAL AND METHODS The material for the study (nose and throat swabs) was collected during the 2021/2022 epidemic season. We analyzed 725 samples from the National Influenza Center, Department of Influenza Research at the National Institute of Public Health NIH-NRI or at 16 Voivodship Sanitary Epidemiological Stations across Poland. Quantitative polymerase chain reaction (qRT-PCR) was applied to determine the influenza virus type and subtype (in RNA isolated from positive samples). RESULTS This study shows the high incidence of influenza among children under the age of 14. Most confirmed infections were caused by influenza A. The genetic material of the A/H1N1/pdm09 subtype was not found among the analyzed samples. The highest number of influenza A infections was among the youngest children (the 0-4 years age group). The most common influenza-like virus was respiratory syncytial virus (RSV). The greatest number of cases caused by this respiratory virus was registered among the youngest children (0-4 years). CONCLUSIONS This study, which shows the high incidence of influenza among children under the age of 14, highlights the importance of regular influenza vaccination. Since children often play a dominant role in spreading influenza virus in the community, regular vaccination can have both health and economic benefits for all age groups.

The Impact of the COVID-19 Pandemic on Influenza Transmission in Poland.

BACKGROUND: The aim of this study was to determine whether the occurrence of the SARS-CoV-2 pandemic affected the incidence of influenza in Poland and the efficiency of the SENTINEL influenza surveillance system. METHODS: The analysis was based on virologic data from the 2018/2019-2021/2022 epidemic seasons. The data in question were obtained from the SENTINEL influenza surveillance system, which is utilized in Poland. RESULTS: In the 2020/2021 epidemic season, only one positive case was confirmed. In the epidemic season of 2021/2022, the number of positive cases increased. There was a delay in the peak of the season, since the start of pandemic, which was observed in the 14th week of 2022. Previously, it was recorded in the 5-10th week, depending on the season. Before the pandemic, the number of positive samples in relation to the tested ones oscillated between 41-49.4%. After the pandemic, it was 0.3% and below 20%, respectively, for season 2020/2021 and season 2021/2022. CONCLUSIONS: The COVID-19 pandemic caused a decline in many other infectious diseases, including influenza, as a result of the numerous lockdowns and from people shifting to remote work. Other safety measures, such as obligatory protective masks and the use of disinfectants, had a significant impact on reducing the number of cases.

Association between the Seroprevalence of Antibodies against Seasonal Alphacoronaviruses and SARS-CoV-2 Humoral Immune Response, COVID-19 Severity, and Influenza Vaccination.

The present study assesses the seroprevalence of antibodies against seasonal human alphacoronaviruses 229E and NL63 among adult patients infected with SARS-CoV-2, and its association with the humoral response to SARS-CoV-2 infection and its severity, and influenza vaccination. A serosurvey was conducted to quantify the presence of IgG antibodies against the nucleocapsid of 229E (anti-229E-N) and NL63 (anti-NL63-N), and anti-SARS-CoV-2 IgG antibodies (against nucleocapsid, receptor-binding domain, S2 domain, envelope, and papain-like protease) for 1313 Polish patients. The seroprevalence of anti-229E-N and anti-NL63 in the studied cohort was 3.3% and 2.4%. Seropositive individuals had a higher prevalence of anti-SARS-CoV-2 IgG antibodies, higher titers of the selected anti-SARS-CoV2 antibodies, and higher odds of an asymptomatic SARS-CoV-2 infection (OR = 2.5 for 229E and OR = 2.7 for NL63). Lastly, the individuals vaccinated against influenza in the 2019/2020 epidemic season had lower odds of seropositivity to 229E (OR = 0.38). The 229E and NL63 seroprevalence was below the expected pre-pandemic levels (up to 10%), likely due to social distancing, increased hygiene, and face masking. The study also suggests that exposure to seasonal alphacoronaviruses may improve humoral responses to SARS-CoV-2 while decreasing the clinical significance of its infection. It also adds to accumulating evidence of the favorable indirect effects of influenza vaccination. However, the findings of the present study are of a correlative nature and thereby do not necessarily imply causation.

Hemagglutinin Antibodies in the Polish Population during the 2019/2020 Epidemic Season.

The aim of the study was to determine the level of antibodies against hemagglutinin of influenza viruses in the serum of subjects belonging to seven different age groups in the 2019/2020 epidemic season. The level of anti-hemagglutinin antibodies was tested using the hemagglutination inhibition (HAI) test. The tests included 700 sera from all over Poland. Their results confirmed the presence of antibodies against the following influenza virus antigens: A/Brisbane/02/2018 (H1N1)pdm09 (48% of samples), A/Kansas/14/2017/ (H3N2) (74% of samples), B/Colorado/06/ 2017 Victoria line (26% of samples), and B/Phuket/3073/2013 Yamagata line (63% of samples). The level of antibodies against hemagglutinin varied between the age groups. The highest average (geometric mean) antibody titer (68.0) and the highest response rate (62%) were found for the strain A/Kansas/14/2017/ (H3N2). During the epidemic season in Poland, only 4.4% of the population was vaccinated.

IgG autoantibodies against ACE2 in SARS-CoV-2 infected patients.

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.

In vitro immune evaluation of adenoviral vector-based platform for infectious diseases.

New prophylactic vaccine platforms are imperative to combat respiratory infections. The efficacy of T and B memory cell-mediated protection, generated through the adenoviral vector, was tested to assess the effectiveness of the new adenoviral-based platforms for infectious diseases. A combination of adenovirus AdV1 (adjuvant), armed with costimulatory ligands (ICOSL and CD40L), and rRBD (antigen: recombinant nonglycosylated spike protein rRBD) was used to promote the differentiation of T and B lymphocytes. Adenovirus AdV2 (adjuvant), without ligands, in combination with rRBD, served as a control. In vitro T-cell responses to the AdV1+rRBD combination revealed that CD8+ platform-specific T-cells increased (37.2 ± 0.7% vs. 23.1 ± 2.1%), and T-cells acted against SARS-CoV-2 via CD8+TEMRA (50.0 ± 1.3% vs. 36.0 ± 3.2%). Memory B cells were induced after treatment with either AdV1+rRBD (84.1 ± 0.8% vs. 82.3 ± 0.4%) or rRBD (94.6 ± 0.3% vs. 82.3 ± 0.4%). Class-switching from IgM and IgD to isotype IgG following induction with rRBD+Ab was observed. RNA-seq profiling identified gene expression patterns related to T helper cell differentiation that protect against pathogens. The analysis determined signaling pathways controlling the induction of protective immunity, including the MAPK cascade, adipocytokine, cAMP, TNF, and Toll-like receptor signaling pathway. The AdV1+rRBD formulation induced IL-6, IL-8, and TNF. RNA-seq of the VERO E6 cell line showed differences in the apoptosis gene expression stimulated with the platforms vs. mock. In conclusion, AdV1+rRBD effectively generates T and B memory cell-mediated protection, presenting promising results in producing CD8+ platform-specific T cells and isotype-switched IgG memory B cells. The platform induces protective immunity by controlling the Th1, Th2, and Th17 cell differentiation gene expression patterns. Further studies are required to confirm its effectiveness.

Analysis of Infections Caused by Influenza Viruses and Influenza-Like Viruses in the Population of People over 65 Years of Age in the 2019-2020 Epidemic Season in Poland.

BACKGROUND Influenza can be the most dangerous for people in risk groups, for example for seniors, in whom it can lead to serious and life-threatening complications. The aim of this research was to analyze the activity of influenza viruses and influenza-like viruses in patients over 65 years of age in the 2019-2020 epidemic season in Poland. MATERIAL AND METHODS A total of 1269 samples collected from patients over 65 years of age with suspected influenza or other respiratory viruses in the 2019-2020 epidemic season (from October 1, 2019, to September 30, 2020) were analyzed. The test material was nose and throat swabs collected during the 2019-2020 epidemic season. Quantitative polymerase chain reaction was used to determine the influenza virus type and subtype for positive samples. RESULTS Among the confirmed infections with influenza viruses, cases due to influenza A were dominant, and the dominant subtype was influenza A subtype A/H1N1/pdm09. Infections with influenza-like viruses were also confirmed in the patients participating in the study, with the presence of genetic material of respiratory syncytial viruses confirmed most often. CONCLUSIONS Seasonal vaccinations can significantly reduce the number of cases and thus the risk of post-influenza complications and deaths among seniors. This is very important, especially now, due to the current epidemiological situation related to the ongoing SARS-CoV-2 respiratory virus pandemic.

Relationship between Humoral Response in COVID-19 and Seasonal Influenza Vaccination.

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.

Importance of Influenza Anti-Hemagglutinin Antibodies During the SARS-CoV-2 Pandemic in the 2019/2020 Epidemic Season in Poland.

BACKGROUND The aim of this study was to determine the level of anti-hemagglutinin antibodies in the serum of recovered patients during the SARS-CoV-2 pandemic in the 2019/2020 epidemic season in Poland, and the course of COVID-19. MATERIAL AND METHODS The material for the study consisted of the sera of COVID-19 convalescents obtained from the following 9 Regional Blood Donation and Blood Supply Centers located in 8 voivodeships. The hemagglutination inhibition reaction assay (HAI) using 8 viral hemagglutination units was used to determine antibody levels, in accordance with WHO recommendations. RESULTS This research confirms that a patient's declared severity of the course of SARS-CoV-2 infection is influenced by the patient's age and concomitant diseases. There was no statistically significant correlation between the level of anti-hemagglutinin antibodies and the severity of the course of a SARS-CoV-2 infection. Based on the serological tests conducted, it can be unequivocally concluded that both vaccinated and influenza-infected patients had a response rate in line with the requirements of the European Commission and the Committee for Medicinal Products for Human Use hemagglutinin antibodies for 4 influenza virus antigens tested. CONCLUSIONS Patients who confirmed their antibody levels with the Commission of the European Communities and the Committee for Propriety Medicinal Products (CPMP) requirements had a mild COVID-19 course. The results of our research emphasize the role of anti-hemagglutinin antibodies in the course of SARS-CoV-2 infection. COVID-19 convalescents have a higher response rate against all 4 types of anti-hemagglutinin antibodies analyzed.

The determination of haemagglutinin influenza antibodies in the Polish population in the epidemic season 2020/2021 during the SARS-CoV-2 pandemic.

The aim of the study was to prove the level of antibodies against haemagglutinin in the sera of people from seven age groups in the epidemic season 2020/2021 in Poland to determine the differentiation of the antibody level and the protection rate depending on age. The level of anti-haemagglutinin antibodies was established by haemagglutinin inhibition test (HAI). A total of 700 randomly selected sera from people belonging to 7 different age groups were tested. The results confirmed the presence of antibodies against the following influenza antigens: A/Guangdong-Maonan/SWL1536/2019 (H1N1)pdm09-like virus, A/Hong Kong/2671/2019 (H3N2)-like virus, B/Washington/02/2019 (B/Victoria lineage)-like virus and B/Phuket/3073/2013 (B/Yamagata lineage)-like virus. The level of haemagglutinin antibodies varied between the studied age groups, with the highest values in the 5-9 age group and the lowest in the 0-4 age group. It was also proven that the protection rate was the highest for the A/Hong Kong/2671/2019(H3N2)-like virus antigen, which exceeded the protection level in the 5 age groups. Considering the very low percentage of people vaccinated in the epidemic season 2020/2021 in Poland, which amounted to only 6.1%, the results should be interpreted as the immune system's response to an infection with influenza virus.

Influenza and Influenza-Like Respiratory Virus Infections in Children During the 2019/20 Influenza Seazon and the COVID-19 Pandemic in Poland: Data from the Department of Influenza Research, the National Influenza Center at the National Institute of Public Health, National Institute of Hygiene-National Research Institute and 16 Voivodeship Sanitary and Epidemiological Stations

BACKGROUND This population study aimed to investigate influenza and influenza-like respiratory virus infections in children during the 2019/20 influenza season and the coronavirus disease 2019 (COVID-19) pandemic in Poland. MATERIAL AND METHODS This study analyzed data from the National Influenza Centre, the Department of Influenza Research at the National Institute of Public Health, and 16 Voivodeship Sanitary and Epidemiological Stations in Poland. Nose and throat swabs were obtained from children during the 2019/20 influenza season and the COVID-19 pandemic. Viral RNA detection was performed using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to diagnose influenza virus infection and viral subtypes. RESULTS In the analyzed group, both cases of influenza A and B and infections with influenza-like viruses were confirmed. Among all cases caused by influenza viruses, influenza A was more frequent than B, with predominance of the A/H1N1/pdm09 subtype. The flu-like virus which infected most children was the human respiratory syncytial virus (RSV). The greatest number of cases with RSV was registered in the group of the youngest children (0-4 years). CONCLUSIONS This population study from Poland showed that during the COVID-19 pandemic, and during the winter influenza season of 2019/20, influenza and influenza-like viral infections in children showed some differences from previous influenza seasons. The findings highlight the importance of viral infection surveillance and influenza vaccination in the pediatric population.

Seasonal Influenza and Low Flu Vaccination Coverage as Important Factors Modifying the Costs and Availability of Hospital Services in Poland: A Retrospective Comparative Study.

Introduction: Influenza infection is associated with potential serious complications, increased hospitalization rates, and a higher risk of death. Materials and Methods: A retrospective comparative analysis of selected indicators of hospitalization from the University Hospital in Wroclaw, Poland, was carried out on patients with confirmed influenza infection in comparison to a control group randomly selected from among all other patients hospitalized on the respective wards during the 2018-2019 influenza season. Results: The mean laboratory testing costs for the entire hospital were 3.74-fold higher and the mean imaging test costs were 4.02-fold higher for patients with confirmed influenza than for the control group; the hospital expenses were additionally raised by the cost of antiviral therapy, which is striking when compared against the cost of a single flu vaccine. During the 2018-2019 influenza season, influenza infections among the hospital patients temporarily limited the healthcare service availability in the institution, which resulted in reduced admission rates to the departments related to internal medicine; the mean absence among the hospital staff totaled approximately 7 h per employee, despite 7.3% of the staff having been vaccinated against influenza at the hospital's expense. Conclusions: There were significant differences in the hospitalization indicators between the patients with confirmed influenza and the control group, which markedly increased the hospital care costs in this multi-specialty university hospital.

Epidemiology of Influenza Viruses and Viruses Causing Influenza-Like Illness in Children Under 14 Years Old in the 2018-2019 Epidemic Season in Poland.

BACKGROUND This study aimed to investigate the epidemiology of influenza viruses and viruses that caused influenza-like disease in children under 14 years of age in the 2018-2019 epidemic season in Poland, and to identify the public health lessons that can be learned. MATERIAL AND METHODS Nose and throat swabs were used to obtain samples. The samples were analyzed in the National Influenza Center, Department of Influenza Research at the National Institute of Public Health-National Institute of Hygiene as well as in 16 Voivodship Sanitary Epidemiological Stations across the country. Methods of RNA isolation depended on the laboratory where the isolation was performed. In all laboratories, quantitative polymerase chain reactions were used to determine the influenza virus type as well as the subtype. RESULTS The study group was confirmed to be infected with influenza A and B, with influenza A/H1N1/pdm09 as the dominant subtype. Among the age group of children up to 14 years of age, cases of infection with viruses that cause influenza-like disease were also reported. It was noticeable that the largest number of confirmed cases of infection was recorded in the group of the youngest children (0-4 years). In addition, several different variants of co-infection were registered. CONCLUSIONS This population study showed that in the 2018-2019 epidemic season in Poland children aged under 14 years were at risk of influenza virus infection and its complications. The presented data support increasing the percentage of children being vaccinated in Poland.

Immunogenicity of Split Inactivated Quadrivalent Influenza Vaccine in Adults with Obesity in the 2017/2018 Season.

BACKGROUND Obesity is associated with susceptibility to severe influenza infection and several disturbances of the immune response to the influenza vaccine. However, the effect of obesity on the immunogenicity of the influenza vaccine is not fully understood. Our objective here was to assess the immunogenicity of the split, inactivated quadrivalent influenza vaccine (QIV) in Polish adults with obesity. MATERIAL AND METHODS Fifty-three subjects with obesity aged 21-69 years were vaccinated with the QIV in 2017/2018 season. Antibody titers against the 4 vaccine strains were measured using the hemagglutination inhibition (HI) assay. The mean fold antibody increase (MFI), seroprotection rate (protection rate, PR), and seroconversion rate (response rate, RR) were calculated to assess vaccine immunogenicity. RESULTS The vaccine elicited a significant increase in the anti-HI titers against the QIV antigens. The MFI, PR, and RR for the QIV antigens also reached the required age-specific values, indicating the QIV meets current immunogenicity criteria. Individuals with class I and class II/III obesity had similar anti-HI titers, MFI, PR, and RR to each of the vaccine strains. Adults aged <60 years had similar anti-HI titers, MFI, PR, and RR to the QIV strains to those aged ≥60 years. CONCLUSIONS Our results indicate that the split virion, inactivated QIV is immunogenic in adults with obesity regardless of their degree of obesity and age (ie, <60 and ≥60 years).

Spread of Influenza Viruses in Poland and Neighboring Countries in Seasonal Terms.

In Poland, flu supervision is coordinated by the National Influenza Center at the National Institute of Public Health-National Institute of Hygiene. In this publication, we want to determine geographical trends in influenza virus circulation in the region. A detailed analysis of virological and epidemiological data showed the course of the epidemic season in Poland, as well as in neighboring countries. The spatial differentiation of the incidence of infection between voivodships was examined, as well as compared to countries that border a given voivodship. The results show a significant variation in the incidence of infection in terms of time and space. This points to the need to increase the number of tests and to raise awareness among health care professionals and the public about the probability of an influenza pandemic, as undetected viruses can spread further into the European Union.

Subtypes of Influenza Virus Infection and Outcomes in Individuals Older than 65 Years of Age in Poland in the 2016/2017 to 2019/2020 Epidemic Seasons.

BACKGROUND Influenza is a viral disease causing many deaths each season. With aging, the human immune system becomes weaker, so people over the age of 65 years are at higher risk of complications after influenza infections. This population study, conducted in Poland, aimed to identify the subtypes of influenza virus infection and outcomes in individuals more than 65 years of age in the 2016/2017 to 2019/2020 epidemic seasons. MATERIAL AND METHODS The research materials were nose and throat swabs. Research was conducted in 16 Voivodship Sanitary and Epidemiological Stations and in the Department of Influenza Research, National Influenza Centre, NIPH-NIH. Methods of RNA isolation depended on the laboratory where the isolation was performed. In all laboratories, quantitative polymerase chain reaction (qRT-PCR) was used to determine the influenza virus type and subtype. RESULTS The analysis of the incidence of influenza among people over the age of 65 included the 2016/2017, 2017/2018, 2018/2019, and 2019/2020 influenza epidemic seasons. We analyzed the percentage of positive samples, the dynamics of epidemic seasons, and the percentage share of influenza viruses in the 65+ age group, according to the epidemic season and percentage of deaths. CONCLUSIONS This population study showed that, in Poland, between the 2016/2017 and 2019/2020 epidemic seasons, people who were more than 65 years of age were at higher risk of influenza virus infection and its complications. The findings support the importance of seasonal influenza vaccination in the population over age 65 years.

Serum Vitamin D and Immunogenicity of Influenza Vaccination in the Elderly.

Vaccination is the most effective preventive measure that reduces the risk of influenza and post-influenza complications. It prevents influenza-related hospitalizations and deaths in 50-60% and about 80% of patients aged over 65, respectively. There is the clinical plausibility of the association between serum vitamin D (VIT D) content and viral respiratory infections. In this study, we addressed the issue of a vitamin D modulatory effect on the immune response to seasonal influenza vaccination in elderly persons. The study comprised 96 participants aged 60-75 during the 2016/17 epidemic season. After the determination of the baseline content of VIT D and anti-hemagglutinin antibodies (H1, H3, and HB), participants were vaccinated with a trivalent vaccine. The content of the anti-hemagglutinin antibodies was rechecked 4-5 weeks afterward, showing inappreciable alterations. The negative findings of this study make the influence of serum VIT D content on the immunogenicity of influenza vaccination highly unlikely in elderly persons.