Background: In 2003, the WHO aimed for a 75% or higher influenza vaccination rate among at-risk populations. However, this target was achieved in a few groups during selected seasons in some European countries, and never in Germany. Adults with underlying conditions (UCs) are a critical negleted group for influenza vaccination. This study aimed to identify data gaps in influenza burden and vaccination coverage among adults under 60 with UCs in Germany and bridge these gaps using real-world data.Material and Methods: We conducted systematic research and analyses using German administrative and claims databases from June 2016 to April 2024. We report on epidemiology, direct care costs, indirect costs from work incapacity, vaccination coverage rates, and describe data gaps.Results: Influenza data for high-risk populations are limited. Comprehensive data on influenza epidemiology and vaccination coverage rates (VCR) is available, though with a delay in data availability. Before and after the pandemic, individuals aged 50-59 had the highest rates of influenza-related hospitalization and ICU admission compared to younger age groups. Across all age groups and seasons, individuals with UC experienced higher rates of medically attended influenza cases, hospitalizations, and healthcare costs, with those aged 35-59 being particularly vulnerable. Vaccine coverage was higher in adults aged 35-59 compared to those aged 18-24, and in females compared to males.Limitations: Discrepancies of vaccination status, limited data availability, and variations among the extent of UCs.Conclusion: In Germany, recent policy measures have mainly targeted those aged 60 and above. While this elderly population experiences the highest disease-related impact, influenza can also lead to substantial healthcare resource utilization (HCRU) and costs in younger populations with chronic UCs; Facilitating vaccination access for this group, such as through pharmacies, is essential. Definition of quantifiable vaccination targets and measures to increase vaccination rates based on these targets are required.

A recent study reported that the high-dose quadrivalent influenza vaccine provided superior immunogenicity and efficacy versus the standard-dose quadrivalent vaccine in the elderly. However, we need to view these results in terms of public health benefits as well. The Number Needed to Vaccinate (NNV) is an important tool to measure the benefit of a given vaccine. Further, NNV evaluates the benefits of a vaccine in preventing and controlling communicable diseases. Considering the target of vaccination and coverage of 75% not met in the elderly in Europe, it is important not to prioritize one vaccine over the other, but rather to increase the vaccine coverage with all the available vaccines.

Purpose: People with noncommunicable diseases (NCDs) have a high risk of contracting flu and suffering from its associated complications; however, in many countries flu vaccine uptake in this group is sub-optimal. This survey assessed the knowledge, attitudes, and gaps toward vaccination in general and flu in particular among adults with NCDs in Europe. Patients and Methods: The survey was conducted in France, Italy, Spain, Germany, Poland, Belgium, Portugal, and the Czech Republic. A structured web-based questionnaire was administered to the subjects. Results: In total, 1106 subjects were enrolled, with 61% aged between 41 and 60 years. The main reasons for getting vaccinated were disease prevention and healthcare practitioner recommendations. Protection against infection and the risks of not receiving a vaccination was the most common vaccine information received, followed by information about possible side effects, duration of protection, and need for a booster dose. In the unvaccinated group, there was a lack of belief in the need for a flu vaccine, with a lack of recommendation from treating practitioners, and the experience of mild severity of flu being the main barriers against the vaccine. The physician remained the most preferred and tapped resource for information followed by dedicated websites. Understanding of flu vaccine benefits was particularly widespread among vaccinated patients, yet > 50% wanted to know more about them. There was less clarity of the benefits of flu vaccine among unvaccinated patients; however, approximately 50% of them wanted to know more about it. Between January 2021 and December 2022, about 30% and 36% of the vaccinated and unvaccinated individuals, respectively, reported having suffered from flu. Conclusion: Healthcare practitioners are the key influencers for people to get vaccinated. The dissemination of information about the importance of flu vaccines needs to be increased, and clear and explanatory messaging based on country-specific characteristics is important.

To understand physicians’ knowledge and perception regarding the effectiveness of influenza vaccines and to communicate the importance of understanding the differences in terms of vaccine efficacy and vaccine effectiveness. This cross-sectional quantitative online survey was conducted using a questionnaire comprising 20 questions, between September 11 and 19, 2021. The survey was conducted across 14 cities in Germany, including physicians actively involved in influenza vaccine purchasing decisions. Descriptive statistics were used to summarize the data and paired t-test was performed to compare the physicians’ understanding of efficacy and effectiveness. Eighty physicians (21%) completed the survey. Physicians defined the terms vaccine efficacy and effectiveness similarly, with only minimal distinctions. Forty-one percent agreed that both terms can be used interchangeably in clinical practice. A higher proportion used the phrase “observational study” for vaccine efficacy and 21% associated “controlled environment” with effectiveness. The majority of physicians indicated that antigen match to circulating strain plays a large role in overall effectiveness and vaccine coverage strongly influences overall influenza case prevention. Vaccine performance in observational studies under so-called “real-world conditions” and (vaccine independent) strain match were the most important factors to assess vaccine performance and vaccine choice. These findings show that physicians in Germany use the terms vaccine efficacy and vaccine effectiveness interchangeably. A better knowledge of the differences between these terms will help to make informed decisions on the choice of influenza vaccine for its population. Finally, and most important, increasing the annual flu vaccine uptake rates will have more and the greatest beneficial impact on reducing flu-related disease and public health, regardless of the expression of the benefits for different vaccine types.

A recent study by Zimmerman et al. (2023) reported non-significant higher relative vaccine effectiveness of recombinant (RIV4) over the standard-dose influenza vaccines (SDIV) against outpatient illness during the 2018-19 and 2019-20 vaccination seasons. We agree with the authors' conclusions and would like to emphasize minimal difference between RIV4 and SDIV using Number Needed to Vaccinate (NNV). The NNV analysis showed 8.9 for the RIV4 and 10 for the SDIV in the 50-64 age group. In the 65+ age group, the NNV was 10.6 for the RIV4 and 11.4 for the SDIV. This indicates a minimal difference between both vaccines and hence they both can be used in immunization programs to improve vaccine coverage.