UNASSIGNED: Vaccination is one of the most effective available public health tools, preventing infectious diseases to safeguard public health and save millions of lives annually. However, in recent years vaccine hesitancy has increased among all populations, including healthcare workers. Healthcare providers are central to vaccination efforts due to their increased exposure to disease and vulnerable patients, and their role in patient confidence and decision-making. These decreasing uptake rates highlight a critical need to address specific barriers within this target group. This systematic review aims to explore the strategies used to improve vaccine uptake among healthcare providers.
UNASSIGNED: A literature search was conducted in PubMed, EMBASE, and MEDLINE databases, alongside a grey literature search, to identify studies describing interventions to improve vaccine uptake among healthcare providers. This was followed by de-duplication and double-blinded screening processes using Rayyan. Data extraction and thematic analysis focused on categorising interventions and identifying frequencies of use, to develop recommendations for further interventions tailored to target regions.
UNASSIGNED: 60 studies were identified, predominantly concerning influenza vaccination. Interventions included educational initiatives, reminders, incentives, access solutions, feedback, and policy implementation. Key strategies included targeted educational lectures, posters, and pamphlets; mobile vaccination units; extended vaccination hours; and leadership engagement. The findings underscore the importance of a multifaceted approach combining educational efforts, enhanced accessibility, and motivational incentives to improve vaccination rates within the healthcare providers, especially where mandatory vaccination is controversial.
UNASSIGNED: This review evaluates tailored strategies to enhance vaccine confidence and uptake among healthcare providers, advocating for a holistic approach that includes educational initiatives, reminder systems, incentives, improved access, feedback mechanisms, and policy enactment to effectively address hesitancy and promote public health.

UNASSIGNED: The potential association between influenza vaccination and SARS-CoV-2 infection and related outcomes is still controversial. The aim of this umbrella review is to represent the impact of previous influenza vaccination and COVID-19 outcomes using evidence currently available in literature.
UNASSIGNED: A literature search of MEDLINE, EMBASE, Scopus, Web of Science and Cochrane Library was conducted. The paper selection was conducted using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) method by two-blinded authors. The quality of meta-analyses was assessed using the AMSTAR 2 scale (A MeaSurement Tool to Assess systematic Reviews). The outcomes investigated were SARS-CoV-2 infection after influenza vaccination, hospitalization, intensive care unit admission, mechanical ventilation and mortality.
UNASSIGNED: The literature research identified 7 ecological studies and 6 meta-analyses. All the ecological studies show a negative relationship between influenza vaccination and COVID-19. The meta-analyses suggest a protective action of influenza vaccination against SARS-CoV-2 infection. Regarding the outcomes evaluated, only two studies reported a statistically significant reduction of 12% and of 17% in hospitalization and intensive care unit admission, respectively. Regarding mechanical ventilation, three studies showed a risk reduction of 31%, 27% and 28%. A substantial reduction of mortality risk was also observed in one study.
UNASSIGNED: These results suggest that influenza vaccination could be associated with reduced susceptibility to SARS-CoV-2 infection, mechanical ventilation and mortality. Our findings highlighted how the administration of flu vaccine in subjects at risk could lead to a reduction in mortality, particularly in the over 65y.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19 and has brought a huge burden in terms of human lives. Strict social distance and influenza vaccination have been recommended to avoid co-infections between influenza viruses and SARS-CoV-2. Scattered reports suggested a protective effect of influenza vaccine on COVID-19 development and severity. We analyzed 51 studies on the capacity of influenza vaccination to affect infection with SARS-CoV-2, hospitalization, admission to Intensive Care Units (ICU), and mortality. All subjects taken into consideration did not receive any anti-SARS-CoV-2 vaccine, although their status with respect to previous infections with SARS-CoV-2 is not known. Comparison between vaccinated and not-vaccinated subjects for each of the four endpoints was expressed as odds ratio (OR), with 95% confidence intervals (CIs); all analyses were performed by DerSimonian and Laird model, and Hartung-Knapp model when studies were less than 10. In a total of 61 029 936 subjects from 33 studies, influenza vaccination reduced frequency of SARS-CoV-2 infection [OR plus 95% CI = 0.70 (0.65-0.77)]. The effect was significant in all studies together, in health care workers and in the general population; distance from influenza vaccination and the type of vaccine were also of importance. In 98 174 subjects from 11 studies, frequency of ICU admission was reduced with influenza vaccination [OR (95% CI) = 0.71 (0.54-0.94)]; the effect was significant in all studies together, in pregnant women and in hospitalized subjects. In contrast, in 4 737 328 subjects from 14 studies hospitalization was not modified [OR (95% CI) = 1.05 (0.82-1.35)], and in 4 139 660 subjects from 19 studies, mortality was not modified [OR (95% CI) = 0.76 (0.26-2.20)]. Our study emphasizes the importance of influenza vaccination in the protection against SARS-CoV-2 infection.

Adults aged 18-64 years comprise most of the working population, meaning that influenza infection can be disruptive, causing prolonged absence from the workplace, and reduced productivity and the ability to care for dependents. Influenza vaccine uptake is relatively low, even among the older adults in this population (i.e., aged 50-64 years), reflecting a lack of perceived need for vaccination. This systematic literature review (SLR) aimed to characterize the global burden of influenza in the 18-64 years population.
An electronic database search was conducted and supplemented with conference and gray literature searches. Eligible studies described at least one of clinical, humanistic, or economic outcomes in adults aged 18-64 years and conducted across several global regions. Included studies were published in English, between January 1, 2012, and September 20, 2022.
A total of 40 publications were included, with clinical, humanistic, and economic outcomes reported in 39, 5, and 15, respectively. Risk of influenza-associated clinical outcomes were reported to increase with age among the 18-64 years population, including hospitalizations (Yamana et al. in Intern Med 60:3401-3408, 2021; Derqui et al. in Influenza Other Respir Viruses 16:862-872, 2022; Fuller et al. in Influenza Other Respir Viruses 16:265-275, 2022; Ortiz et al. in Crit Care Med 42:2325-2332, 2014; Yandrapalli et al. in Ann Transl Med 6:318, 2018; Zimmerman et al. in Influenza Other Respir Viruses 16:1133-1140, 2022). ICU admissions, mortality, ER/outpatient visits, and use of mechanical ventilation were recorded. Adults aged 18-64 years with underlying comorbidities were at higher risk of influenza-related hospitalizations, ICU admission, and mortality than otherwise healthy individuals. Length of hospital stay increased with age, although a lack of stratification across other economic outcomes prevented identification of further trends across age groups.
High levels of hospitalization and outpatient visits demonstrated a clinical influenza-associated burden on patients and healthcare systems, which is exacerbated by comorbidities. Considering the size and breadth of the general population aged 18-64 years, the limited humanistic and economic findings of this SLR likely reflect an underreported burden. Greater investigation into indirect costs and prolonged absenteeism associated with influenza infection is required to fully understand the economic burden in this population.

Influenza is common in healthy children and adolescents and is associated with a high rate of hospitalization in this group, especially for those <5 years. Although the WHO has recommended vaccination in children under 5 years of age since 2012, it is really implemented in few countries today. The aim of this paper was to review the available evidence on the efficacy/effectiveness of influenza vaccination in healthy children <18 years of age through a non-systematic search of studies conducted between 2010 and 2020. Despite the high variability in results due to differences in design, vaccine type and season included in the 41 selected studies, statistically significant studies show efficacy values for the influenza vaccine of between 25.6% and 74.2%, and effectiveness from 26% to 78.8%. Although a systematic review would be necessary to corroborate the evidence, this review suggests that paediatric vaccination is generally an effective measure for preventing influenza in healthy children in line with international organisms\' recommendations.

Vaccination is the most effective intervention to prevent influenza. Adults at risk of complications are among the targets of the vaccination campaigns and can be vaccinated with different types of quadrivalent influenza vaccines (QIVs). In the light of assessing the relative immunogenicity and efficacy of different QIVs, a systematic review was performed. Randomized controlled trials conducted in adults aged 18-64 years until 30 March 2021 were searched through three databases (Medline, Cochrane Library and Scopus). Twenty-four RCTs were eventually included. After data extraction, a network meta-analysis was not applicable due to the lack of common comparators. However, in the presence of at least two studies, single meta-analyses were performed to evaluate immunogenicity and efficacy; on the contrary, data from single studies were considered. Seroconversion rate for H1N1 was higher for standard QIVs, while for the remaining strains it was higher for low-dose adjuvanted QIVs. For seroprotection rate, the recombinant vaccine recorded the highest values for H3N2, while for the other strains, the cell-based QIVs achieved better results. In general, standard and cell-based QIVs showed an overall good immunogenicity profile. Nevertheless, as a relative comparative analysis was not possible, further research would be deserved.

UNASSIGNED: A number of cost-effectiveness analysis of influenza vaccination have been conducted to estimate value of influenza vaccines in elderly and health workers (HWs). This study aims to summarize cost-effectiveness evidence by pooling the incremental net monetary benefit (INMB) of influenza vaccination.
UNASSIGNED: A systematic review was performed in electronic databases from their inceptions to February 2022. Cost-effectiveness studies reporting quality-adjusted life year (QALY), or life year (LY) of influenza vaccination were included. Stratified meta-analyses by population, perspective, country income-level, and herd-effect were performed to pool INMB across studies. The protocol was registered at PROSPERO (CRD42021246746).
UNASSIGNED: A total of 21 studies were included. Eighteen studies were conducted in elderly, two studies were conducted in HWs, and one study was conducted in both elderly and HWs. According to pre-specified analyses, studies for elderly in high-income economies (countries) (HIEs) and upper-middle income economies (UMIEs) without herd effect could be pooled. For HIEs under a societal perspective, the perspective which identify all relevant costs occurred in the society including direct medical cost, direct non-medical cost and indirect cost, pooled INMB was $217·38 (206·23, 228·53, I2 =28.2%), while that for healthcare provider/payer perspective was $0·20 (-11,908·67, 11,909·07, I2 = 0.0%). For societal perspective in UMIEs, pooled INMB was $28·39 (-190·65, 133·87, I2 = 92.8%). The findings were robust across a series of sensitivity analyses for HIEs. Studies in HWs indicated that influenza vaccination was cost-effective compared to no vaccination or current practice.
UNASSIGNED: Influenza vaccination might be cost-effective for HWs and elderly in HIEs under a societal perspective with relatively small variations among included studies, while there remains limited evidence for healthcare provider/payer perspective or other level of incomes. Further evidence is warranted.
UNASSIGNED: This study was funded by a grant of Immunization, Vaccine and Biologicals department of the World Health Organization. The authors would like to acknowledge the contributions of the US CDC which provided financial support to the development and publication of this report. Grant number US CDC, WHO IVR (U50CK000431).

Influenza is an acute respiratory disease caused by the influenza virus which often occurs in outbreaks and epidemics worldwide. The World Health Organization recommends annual vaccination of healthcare workers (HCWs) against influenza, because most of them are involved in the direct care of patients with a high risk of influenza-related complications. Given the significance of the disease burden, a targeted literature review was conducted to assess issues related to influenza vaccination among HCWs. The primary aim of this review was to assess the incidence of influenza among medical personnel and healthcare-associated influenza, and to outline the benefits of influenza vaccination for patients and HCWs themselves. Vaccination of HCWs seems to be an important strategy for reducing the transmission of influenza from healthcare personnel to their patients and, therefore, for reducing patient morbidity and mortality, increasing patient safety, and reducing work absenteeism among HCWs. The benefits of influenza vaccination for their patients and for HCWs themselves are addressed in literature, but the evidence is mixed and often of low-quality. Int J Occup Med Environ Health. 2022;35(2):127-39.

A systematic review and meta-analysis was conducted to estimate the pooled effect of influenza vaccinations for health workers (HWs). Nine databases were screened to identify randomized clinical trials and comparative observational studies that reported the effect of influenza vaccination among HWs. The risk ratio (RR), standardized mean difference, and 95% confidence interval (CI) were employed to study the effect size using fixed/random-effect models. Subgroup analyses and sensitivity analyses were conducted accordingly. Publication bias was examined. Sixteen studies (involving 7971 HWs from nine countries) were included after a comprehensive literature search. The combined RR regarding the incidence of laboratory-confirmed influenza was 0.36 (95% CI: 0.25 to 0.54), the incidence of influenza-like illness (ILI) was 0.69 (95% CI: 0.45 to 1.06), the absenteeism rate was 0.63 (95% CI: 0.46 to 0.86), and the integrated standardized mean difference of workdays lost was -0.18 (95% CI: -0.28 to -0.07) days/person. The subgroup analysis indicated that vaccination significantly decreases the incidence of laboratory-confirmed influenza in different countries, study populations, and average-age vaccinated groups. Influenza vaccinations could effectively reduce the incidence of laboratory-confirmed influenza, absenteeism rates, and workdays lost among HWs. It is advisable, therefore, to improve the coverage and increase the influenza vaccination count among HWs, which may benefit both workers and medical institutions.

This study aimed to identify effective strategies for improving the uptake of influenza vaccination and to inform recommendations for influenza vaccination programs in Australia. A rapid systematic review was conducted to assimilate and synthesize peer-reviewed articles identified in PubMed. The National Health and Medical Research Council (NHMRC) Hierarchy of Evidence was used to appraise the quality of evidence. A systematic search identified 4373 articles and 52 that met the inclusion criteria were included. The evidence suggests influenza vaccination uptake may be improved by interventions that (1) increase community/patient demand and access to influenza vaccine and overcome practice-related barriers; (2) reinforce the critical role healthcare providers play in driving influenza vaccination uptake. Strategies such as standing orders, reminder and recall efforts were successful in improving influenza vaccination rates. Community pharmacies, particularly in regional/remote areas, are well positioned to improve influenza vaccine coverage. The findings of this rapid review can be utilized to improve the performance of influenza immunization programs in Australia and other countries with comparable programs; and recommend priorities for future evaluation of interventions to improve influenza vaccination uptake.