Influenza Vaccine Research Articles

Influenza vaccine averted illnesses in Chile, Guyana, and Paraguay during 2013-2018: a standardized approach to assess value of vaccination.

To better establish the value of vaccination against influenza viruses, we estimated vaccine-averted influenza illnesses among young children and older adults in Chile, Guyana, and Paraguay. We gathered country- and target population-specific data on monthly influenza hospitalizations, vaccine coverage, and vaccine effectiveness from surveillance records and immunization registries during 2013-2018. We applied a static compartmental model to estimate differences in the number influenza-associated respiratory disease events (symptomatic non-hospitalized illnesses, medically attended illnesses, hospitalizations) in the presence and absence of influenza vaccination programs. Between 2013 and 2018, vaccinating 68% of children aged 6-23 months in Chile averted an annual mean of 14,617 non-hospitalized, 9,426 medically attended, and 328 hospitalized influenza illnesses; vaccinating 28% of children aged 6-23 months in Paraguay averted 1,115 non-hospitalized, 719 medically attended, and 25 hospitalized influenza illnesses. Vaccinating 59% of older adults in Chile averted an annual mean of 83,429 non-hospitalized, 37,079 medically attended, and 1,390 hospitalized influenza illnesses; vaccinating 36% of older adults in Paraguay averted an annual mean of 3,932 non-hospitalized, 1,748 medically attended, and 66 hospitalized influenza illnesses. In Guyana, a hypothetical campaign vaccinating 30% of children <5 years could have prevented an annual 1,496 non-hospitalized, 971 medically attended, and 10 hospitalized influenza illnesses. Vaccinating 30% of adults ≥65 years could have prevented 568 non-hospitalized, 257 medically attended, and 10 hospitalized influenza illnesses. Influenza vaccination averted tens of thousands of illnesses and thousands of hospitalizations in Chile and Paraguay; influenza vaccination could have had a proportional benefit in Guyana.

Factors influencing nurses and nursing students' attitudes towards vaccinations: – A cross-sectional study

BackgroundVaccination hesitancy remains the main obstacle to improving vaccination coverage. Influenza and COVID-19 vaccination coverage among healthcare professionals is essential. It is crucial to study the vaccination attitudes of healthcare professionals as they significantly influence the vaccination attitudes and behaviour of the rest of the population. ObjectiveThe aim of this study was to describe the attitudes of Finnish nurses and nursing students towards COVID-19 and Influenza vaccination and explain what factors influence these attitudes. DesignA cross-sectional study. Setting and participantsA total of 1353 nurses from five hospital organisations and 580 nursing students from eight Universities of Applied Sciences participated in the survey. Participants were invited to complete the questionnaire through Webropol between March and September 2023. MethodsTo collect data anonymously, a self-reported web-based questionnaire combining the Vaccination Attitude Examination (VAX) scale and Bergen's Social Media Addiction (BSMA) scale was used. K-means cluster analysis was performed to describe vaccination attitude profiles. ResultsFour distinct vaccination attitude profiles were identified: Profile A - Confident Pro-Vaccine (n = 605) exhibited low hesitancy, with high confidence in vaccine safety and effectiveness; Profile B – Cautiously Pro-Vaccine (n = 764) showed moderate hesitancy, mainly concerned about unforeseen future effects; Profile C - Hesitant with Mistrust (n = 405) expressed high hesitancy, with significant worries about vaccine safety and mistrust in health authorities; and Profile D – Strongly Vaccine-Hesitant (n = 159) demonstrated very high hesitancy, marked by strong beliefs in potential long-term negative effects of vaccination. Significant differences in VAX-scale mean scores were found between the profiles, ranging from 1.27 for Profile A to 6.65 for Profile D. Overall, nursing students were more hesitant than practising nurses, with students being overrepresented in the more hesitant profiles. Clinical training in a COVID-19 unit was associated with more favourable vaccination attitudes among nursing students. The uptake of the full series of COVID-19 and annual Influenza vaccines was generally high in the sample (90.8 % and 87 %, respectively). However, a clear pattern between specific social media use and vaccination attitudes was not found. Major concerns related to vaccine hesitancy focused on the uncertainty of vaccines' long-term effects. ConclusionThis study provides valuable insights into the complex nature of vaccination hesitancy among nurses and nursing students. These findings underscore the need for targeted interventions to address underlying concerns and promote vaccine acceptance within this demographic. In future research, it would be essential to gather more in-depth knowledge, particularly regarding nursing students' attitudes towards vaccination and the factors influencing them.

Barriers to influenza vaccination during pregnancy in France: A national population-based study.

Despite French national recommendations since 2012 that all pregnant women be vaccinated against influenza, in 2021 this vaccine coverage is low - around 30% - in France. To identify barriers to influenza vaccination during pregnancy by assessing how often women were offered this vaccination and how often they accepted it. We used data from the French national perinatal survey (ENP), which covered all births during one week in March 2021 (N=12,614). Data came from medical files and face-to-face postpartum interviews. We excluded women who: refused to participate (n=91), agreed only to complete the minimal questionnaire (n=435), were not interviewed (N=1130), or had medical records not mentioning influenza vaccination (N=120). Factors associated with no offer of influenza vaccination during pregnancy and with refusal of offers that were made were assessed by univariate and multivariate analyses. Among the 10,838 women included, 40.7% (95% CI, 39.8-41.6) (n=4411) reported that they had not been offered this vaccination. This group was younger, (adjusted prevalence ratio (PRa) for women below 25years was 1.23 (95% CI, 1.14-1.33)), multiparous more often (PRa 1.37 (95% CI, 1.27-1.49)), born abroad more often (PRa 1.20, 95%CI, 1.12-1.29 and less well educated (PRa 1.46 (95%CI, 1.34-1.58). Among the 6427 women to whom influenza vaccination was offered during pregnancy, 3463 (53.9%) were not vaccinated. This group was also younger, (PRa 1.23 (95% CI, 1.14-1.33)), more often multiparous (PRa 1.18; 95% CI, 1.07-1.30) and had a lower education level (PRa 1.70 (95% CI, 1.56-1.85)). The low influenza vaccine coverage in France seems mainly related to the failure to offer the vaccine, in particular to those young and less educated. Our study identifies key points of leverage to improve vaccine coverage and reduce the persisting burden of this severe infection.

Immunogenicity in mice and non-human primates of an Advax-CpG55.2-adjuvanted recombinant hemagglutinin seasonal quadrivalent influenza vaccine.

There is a need to improve the effectiveness of seasonal influenza vaccines. Influenza vaccines based on recombinant hemagglutinin offer advantages over traditional approaches. We asked whether Advax-CpG55.2 or alum-CpG55.2 adjuvants could enhance the immunogenicity of a quadrivalent influenza vaccine (QIV) comprising recombinant full-length native hemagglutinins (HA0) produced in Sf9 insect cells. Adult C57BL/6 mice were immunized intramuscularly twice 10days apart with 4μg of QIV alone or with adjuvant. QIV induced only modest levels of anti-influenza IgG1 whereas the adjuvanted formulations induced significantly higher levels of IgG1 plus IgG2c. When challenged with the H1N1pdm strain, A/South Australia/348/2023, adjuvanted QIV immunized mice showed minimal illness, whereas QIV alone immunized mice all succumbed to infection. Advax-CpG55.2 adjuvanted QIV similarly increased influenza-specific IgG against all four vaccine strains in Cynomolgus macaques. Adjuvanted recombinant hemagglutinin approaches offer a promising alternative to existing seasonal influenza vaccine platforms.

Comparison of neuraminidase inhibiting antibody responses elicited by egg- and cell-derived influenza vaccines.

An immunogenicity sub-study was performed within a clinical trial comparing the effectiveness of egg, cell, and recombinant hemagglutinin (HA)-derived influenza vaccines during the 2018-2019 and 2019-2020 influenza seasons. NAI and neutralizing antibody titers against the A(H1N1)pdm09 and A(H3N2) components of the vaccines were measured in pre- and post-vaccination sera. Responses to the N1 component of eIIV and cIIV were different in both study years 1 and 2 whereas response rate and antibody titers to the N2 component of egg and cell culture-derived vaccines were similar. For example, 43.5% of eIIV and no cIIV recipients had four-fold NAI titer increases in year 1. There was a weak positive correlation between responses to N1 and N2 for both vaccine types but no correlation between NAI and HA-specific neutralizing antibody responses. Recombinant HA vaccine that does not contain NA served as a specificity control; NAI antibody titers did not increase in recipients except in two individuals presumed to have subclinical infection. Antibody responses to NA following vaccination with eIIV and cIIV were not the same; although the responses to the N1 and N2 components of eIIV were similar, there were fewer responders to N1 than N2 of cIIV. Studies to determine the impact of NA immunity on influenza vaccine effectiveness are warranted.

Effectiveness of 2023 southern hemisphere influenza vaccines against severe influenza-associated illness: pooled estimates from eight countries using the test-negative design.

Annual estimates of seasonal influenza vaccine effectiveness can guide global risk communication and vaccination strategies to mitigate influenza-associated illness. We aimed to evaluate vaccine effectiveness in countries using the 2023 southern hemisphere influenza vaccine formulation. We evaluated end-of-season influenza vaccine effectiveness across eight countries (Argentina, Australia, Brazil, Chile, New Zealand, Paraguay, Thailand, and Uruguay) that used the 2023 southern hemisphere vaccine formulation, with use of a test-negative design. All patients who attended participating hospitals with severe acute respiratory illness were tested by RT-PCR for influenza. We calculated country-specific, network-specific, and pooled vaccine effectiveness against hospitalisation. For countries with sufficient data, we also calculated vaccine effectiveness against intensive care unit (ICU) admission by comparing the odds of vaccination among test-positive cases to that among test-negative controls. We evaluated vaccine effectiveness for groups prioritised for vaccination (young children aged 1-4 years, people aged 5-64 years with underlying health conditions, and older adults aged ≥65 years). From March 5 to Nov 27, 2023, 31 368 individuals were admitted to hospital with severe acute respiratory infection in the eight included countries. Of these, 12 609 individuals admitted to hospital (6452 [51·2%] female and 6157 [48·8%] male) who met inclusion criteria and had complete data were included in the analysis, including 4388 test-positive cases and 8221 test-negative controls. Pooled vaccine effectiveness against hospitalisation with any influenza virus was 51·9% (95% CI 37·2-66·7), with substantial heterogeneity across countries (I2 74%). Vaccine effectiveness against ICU admission from any influenza virus was 67·7% (44·5-81·2) in Chile and 69·7% (45·3-83·3) in Australia. Vaccine effectiveness estimates against hospitalisation were highest for young children (70·9% [47·5-94·4]) and lowest for older adults (47·7% [24·9-70·5]). Across eight countries, 2023 southern hemisphere vaccines were effective in reducing hospitalisations from influenza illness. Use of common protocols can facilitate data pooling to provide a comprehensive evaluation of vaccine effectiveness across settings. US Centers for Disease Control and Prevention cooperative agreements to the Pan American Health Organization and the Thailand Ministry of Public Health; the Australian Government Department of Health and Aged Care; and the New Zealand Ministry of Health.

Promoting aged care COVID-19 and influenza vaccination through education of Australian residential aged care staff: A mixed methods project evaluation.

Vaccination coverage against COVID-19 and influenza among Australian aged care residents remains suboptimal, placing this vulnerable population at heightened risk of severe illness, frailty, and death. Health care professionals' recommendations significantly influence vaccination uptake. Aged care staff, with their unique proximity to residents, play a pivotal role in promoting vaccination. The aims of this study were to evaluate the acceptance of a vaccine education project and determine the impact on vaccine conversation confidence. This quality improvement project aimed to enhance aged care staff's knowledge and confidence in discussing vaccination with residents and their families. It included a 30-min face-to-face educational session for staff members of residential aged care facilities. The session featured a didactic component on COVID-19 and influenza vaccines, an interactive question and answer component, and role-play exercises to demonstrate effective vaccine conversation skills. Evaluation of the project involved participant survey data collected immediately after the sessions and then again at a delayed timepoint. Project developers, co-ordinators, and facilitators also provided feedback on their experience which was analysed through qualitative thematic analysis. The educational program was delivered to 27 facilities across 32 sessions, with 316 staff members attending (median session attendance: 9, IQR 8-13). 95.4% of attendees reported improved knowledge and skills, 95.8% reported increased confidence in vaccine conversations, and 94.2% would recommend the session to others. Qualitative feedback was positive, highlighting the adequacy of content and improved confidence in discussing vaccines. In-house, face-to-face education is a well-received method of delivering education to residential aged care staff. However, facilities in most need of education may be less proactive in seeking it out. Further research is needed to understand barriers to uptake of staff education and strategies for fostering a culture of quality improvement and ongoing learning within facilities.

Effect of Childcare Influenza Vaccine Requirement on Vaccination Rates, New York City, 2012-2020.

In 2014, New York City initiated a childcare influenza vaccine requirement to increase influenza vaccination rates among children aged 6-59 months attending city-regulated childcare, including prekindergarten. We evaluated the requirement's effect on vaccination rates in childcare-aged children in New York City. We examined influenza vaccination rates in children aged 6-59 months and by age groups of 1, 2, 3, and 4 years for 8 influenza seasons (2012-2013 through 2019-2020), representing 2 seasons before the requirement, 2 seasons during the requirement, 2 seasons after its suspension, and 2 seasons after its reinstatement. We also assessed rates in a comparison group of children aged 5-8 years. We performed a difference-in-differences analysis to compare rate differences in age groups when the requirement was and was not in effect. We considered P < .05 as significant based on the Wald χ2 test. Influenza vaccination rates among children aged 6-59 months increased 3.7 percentage points (from 47.7% to 51.4%) by the requirement's second year and declined 6.7 percentage points to 44.7% after suspension. After reinstatement, rates increased 10.7 percentage points to 55.4%. Rate changes were most pronounced among 4-year-olds, increasing 12.7 percentage points (from 45.3% to 58.0%) by the requirement's second year, declining 14.1 percentage points to 43.9% after suspension, and increasing 22.2 percentage points to 66.1% after reinstatement. In the comparison group, rates increased 4.9 percentage points (from 36.5% to 41.4%) after reinstatement. Rates increased significantly among 4-year-olds before versus at the initial requirement and decreased significantly after suspension. After reinstatement, rates increased significantly among all groups except 1-year-olds. The New York City influenza vaccine requirement improved influenza vaccination rates among preschool-aged children, adding to the evidence base showing that vaccine requirements raise vaccination rates.

Critical assessment of uncertainty in economic evaluations on influenza vaccines for the elderly population in Spain

BackgroundInfluenza is a seasonal infection with a huge impact on morbidity and mortality in older adults, for whom vaccination is recommended. New influenza vaccines for this population have been introduced in Spain in the past 5 years, and a number of cost-effectiveness analyses (CEA) have been published to aid healthcare decision-making. The objective of this study was to assess possible sources of uncertainty in the CEAs of influenza vaccines for the older adults in Spain.MethodsA systematic review was performed to identify Spanish CEAs published since 2016. Potential sources of structural, methodologic and parametric uncertainty in CEA results were systematically analysed using the TRansparent Uncertainty ASsessmenT (TRUST) Tool, quality assessment checklists, and the WHO guidance on economic evaluations of influenza vaccine strategies. The primary sources of efficacy/effectiveness were analysed in depth to ascertain whether they could support the conclusions of the respective CEAs.ResultsSeven CEAs were included. Overall, they were designed and performed in accordance with the applicable guidelines; however, some critical sources of uncertainty were detected, mainly: (1) the choice and use of efficacy/effectiveness data (real-world single season studies, meta-analyses including studies with high risk of bias and/or high heterogeneity with biased interpretation); (2) use of fewer than 5 seasons to estimate influenza burden; (3) generalized use of influenza-like illness data to estimate effectiveness and burden, among others.ConclusionsSeemingly well-designed studies may conceal important sources of uncertainty that affect the results. This must be taken into account when interpreting results to support decision-making.

Receipt of respiratory vaccines among patients with heart failure in a multicenter health system registry.

Heart failure affects people of all ages and is a leading cause of death for both men and women in most racial and ethnic groups in the United States. Infections are common causes of hospitalizations in heart failure, with respiratory infections as the most frequent diagnosis. Vaccinations provide significant protection against preventable respiratory infections. Despite being an easily accessible intervention, prior studies suggest vaccines are underused in patients with heart failure. An observational study of 5089 adults with heart failure was conducted using data from an integrated, multicenter, academic health system in Southern California from 2019 to 2022. Logistic regression models were used to determine the rates of influenza, pneumococcal, and COVID-19 vaccination among a population of patients with heart failure (heart failure preserved ejection fraction [HFpEF], heart failure mildly reduced ejection fraction [HFmrEF], and heart failure reduced ejection fraction [HFrEF], and identify whether heart failure phenotype is associated with vaccination status. Vaccination rates varied between influenza, pneumococcal, and COVID-19 vaccines. Of the three respiratory vaccines, 58.0% of patients had received an influenza vaccine, 76.2% had received a pneumococcal vaccine, and 83.3% had received a COVID-19 vaccine. There were no sex-based differences by vaccination status. Differences were seen within age, race/ethnicity, insurance type, whether the patient was a member of an Accountable Care Organization (ACO), primary language, Social Vulnerability Index (SVI) score, clinician type, and number of comorbidities. Patients with HFpEF and HFmrEF had higher vaccination rates than HFrEF. In adjusted models, patients with HFrEF had lower odds of being vaccinated for influenza (aOR=0.75, 95% CI=0.66-0.86), pneumococcal (aOR=0.65, 95% CI=0.55-0.75), and COVID (aOR=0.74, 95% CI=0.62-0.89) compared to patients with HFpEF. Patients with HFrEF had the lowest levels of respiratory vaccination compared to other specified heart failure categories. Interventions are needed to increase vaccination education and offerings, especially to patients with HFrEF.

Safety and immunogenicity of ascending doses of influenza A(H7N9) inactivated vaccine with or without MF59®.

While it remains impossible to predict the timing of the next influenza pandemic, novel avian influenza A viruses continue to be considered a significant threat. A Phase II study was conducted in healthy adults aged 18-64years to assess the safety and immunogenicity of two intramuscular doses of pre-pandemic 2017 influenza A(H7N9) inactivated vaccine administered 21days apart. Participants were randomized (n=105 in each of Arms 1-3) to receive 3.75μg, 7.5μg or 15μg of hemagglutinin (HA) with MF59® adjuvant, or 15μg of HA unadjuvanted vaccine (n=57, Arm 4). The three MF59 adjuvanted vaccines and the 15μg unadjuvanted vaccine were safe and well-tolerated. Little antibody activity was detected against the A(H7N9) vaccine antigen after the first vaccination across study Arms. After second vaccination, the three adjuvanted Arms showed increases in hemagglutination inhibition (HAI), neutralizing (Neut), and neuraminidase inhibition (NAI) geometric mean titers (GMT), peaking at 21days post second vaccination. The percentage of participants with titer ≥1:40 and seroconversion rates for HAI were 30-43% and 0 for the adjuvanted Arms and the unadjuvanted Arm, respectively. Antibody responses against antigenically drifted A(H7N9) strains A/Shanghai/2/2013 and A/Guangdong/17SF003/2016 showed similar trends. Exploratory linear modeling of HAI and Neut responses post second vaccination revealed significantly lower log antibody titers among older participants (aged 35-49 and 50-64years) compared to participants aged 18-34years after adjusting for study vaccination, BMI, sex, and prior seasonal influenza vaccination. Post second vaccination, participants who received seasonal influenza vaccination in at least one of the two previous seasons had significantly lower log antibody titers than participants who did not. Adjuvanted doses of vaccine provided higher antibody responses, on average, than the 15μg unadjuvanted vaccine. Proportion of participants achieving seroconversion and antibody titers ≥40 remained below 50% in all study Arm.

Understanding factors contributing to vaccination underutilization among Jewish ultra-orthodox communities in Israel: A cross-sectional study.

This study aims to investigate the factors contributing to the underutilization of childhood and school-age immunizations among parents within the Jewish Ultra-Orthodox community in Israel. It identifies socio-demographic, attitudinal, and belief-related risk factors that affect vaccination decisions. A cross-sectional study was conducted involving 369 Jewish Orthodox parents in Israel, using structured questionnaires distributed through various community channels. Data on socio-demographic variables, vaccination status, and intentions were collected. Attitudinal assessments included the VAX Scale and the Multidimensional Health Locus of Control Scale. The proportion of fully vaccinated children was 46.3% for childhood diseases and 64.2% for school-age vaccinations. Flu vaccination rates were significantly lower, with only 19.2% of parents and 15.2% of children receiving flu shots. Key factors contributing to vaccine underutilization include large family size, lower socioeconomic and educational levels, reliance on the internet for health information, and the absence of media technology at home. Geographical disparities were notable, especially in the Jerusalem District, which demonstrated lower vaccination uptake, and among different Orthodox streams, with the Modern stream showing higher vaccination rates compared to the Lithuanian, Sephardic, and Hasidic streams. The VAX scale and Health-Related Locus of Control measures revealed that attitudinal factors significantly impacted vaccination decisions, such as mistrust in vaccine benefits, preference for natural immunity, and reliance on religious beliefs. To address vaccination disparities, targeted interventions should consider cultural and logistical barriers, engaging community leaders and offering culturally sensitive education to improve uptake within the Jewish ultra-Orthodox community.

Immunogenicity and safety of live attenuated influenza vaccine in children aged 3-17years in China.

(1) Background: The administration of a live attenuated influenza vaccine (LAIV) has emerged as a viable option for preventing pediatric infections. The LAIV vaccine is available in China based on efficacy results. However, LAIV immunogenicity in children aged 3-17years old in China has not yet to be studied and reported broadly. (2) Methods: This is a substudy investigating the immunogenicity and safety of the LAIV under a Phase 3, multicentre, randomized, double-blind, placebo-controlled trial. A total of 3000 participants were enrolled in a randomized, double-blind, placebo-controlled trial, split in half between vaccine and placebo, was conducted to evaluate a single LAIV dose in this age group. Hemagglutination inhibition (HI) antibody titers and incidence of adverse events were used to evaluate immunogenicity and safety, respectively. (3) Results: Although there was no significant difference in frequencies of all solicited or unsolicited AEs, nasal congestion, headache, and muscle pain were statistically significantly more frequent in vaccine recipients as compared to placebo Seroconversions and geometric mean fold increases in HI antibody titers against all strains were significantly higher in the vaccine group than in the placebo group. (4) Conclusions: The LAIV is safe and immunogenic in Chinese children and adolescents.

Harnessing the power of multicountry networks for influenza vaccine monitoring.

Harnessing the power of multicountry networks for influenza vaccine monitoring.

Annual estimation of seasonal influenza burden in six South American countries: a retrospective analysis of SARInet surveillance data to inform policies.

We estimate annual viral influenza-associated mild-to-moderate illness, hospitalizations, and deaths in six South American countries (Argentina, Brazil, Chile, Ecuador, Paraguay, and Uruguay) during the 2015-2019 influenza seasons as a first step in evaluating the full value of influenza vaccination in the subregion. We applied a multiplier methodology using monthly hospital discharge and vital statistics death records, influenza surveillance data, and population projections to estimate mild-to-moderate influenza-associated illness, hospitalizations, and deaths. We estimated the uncertainty bounds based on the 2.5th and 97.5th of the Monte Carlo simulated distributions for the number of cases and obtained the ranges from the minimum value of the 2.5th percentile and the maximum value of the 97.5th percentile. In selected countries with a total population of 307 million people, the yearly influenza-associated burden of disease ranged between 51 and 78 million mild-to-moderate influenza illnesses, between 323,379 and 490,049 hospitalizations, and between 22,662 and 46,971 deaths during the 2015-2019 influenza seasons. Each year, influenza is associated with millions of illnesses, hundreds of thousands of hospitalizations and tens of thousands of deaths in six South American countries, affecting a significant portion of the population. Such findings can be used to estimate the number of illnesses averted through vaccination programs and the cost-benefit of influenza vaccines.

Optimization of formulation and device design for carrier-based nasal powder of influenza vaccine to maximize the delivery capability to the target site in the nasal cavity

Previously, a nasal powder formulation of the influenza vaccine was proposed to ensure its stability over fifteen months at room temperature and to have sufficient moisture-resistant characteristics to enable handling without special humidity control. In this study, a carrier-based concept: a physical mixture of the antigen powder and the carrier powder, was adopted for this nasal powder formulation. The physical properties of both components were optimized to maximize the delivery capability to the target site located behind the nasal cavity using a human nasal cast model. Preliminary evaluation with a prototype device (Device A) revealed that the physical properties of the antigen powder influenced the delivery efficiency mainly through their effect on the discharge rate from the device. Since it is obvious that the discharge rate from the device must be secured as a prerequisite for increasing the target site delivery, Device B with an improved discharge rate was developed, and the optimal powder properties were re-evaluated. The delivery rate of antigen powder to the target site was broken down into two elements: the discharge rate from the device and the delivery efficiency of emitted powder to the target site, and then the effect of the particle size of antigen powder and the carrier powder on each element was analyzed separately. As a result, an optimal particle size region was identified for each element as a design space on a two-dimensional map described by the antigen particle size and the carrier particle size. Besides this analysis, the fine particle fraction (aerodynamic particle size less than 5 μm) was evaluated in a separate experiment considering the risk of invasion into the lung and a condition of particle size to minimize the fine particle fraction was identified. By integrating the results of the above analysis, an optimal space was determined on the two-dimensional map to maximize the delivery efficiency to the target site while minimizing unintended exposure to the lungs.

235 Improving influenza vaccination rates in an academic general pediatrics clinic for 2024–25

235 Improving influenza vaccination rates in an academic general pediatrics clinic for 2024–25

The Level of Knowledge and Performance of Iranian Medical Students in The Second Year of the COVID-19 Pandemic

Introduction: It has been four years since the onset of the COVID-19 pandemic. In addition to medical professionals, medical students have also been at the forefront of the fight against this pandemic and, like them, have been highly susceptible to the virus. The aim of this study was to evaluate the level of knowledge of Iranian medical students about COVID-19, preventive behaviors, and their perception of risk in the second year of this pandemic. Methods: The study was conducted from January to October 2021 (during the fourth and fifth waves of COVID-19) on Iranian medical students who were undergoing clinical courses in university hospitals. In this study, an online questionnaire consisting of 48 questions in Persian was provided to the students. Results: After sending an electronic questionnaire to the students, 401 medical students from Lorestan University of Medical Sciences participated in the survey. Of these, 62.8% were studying medicine in the medical field. About 66.1%, 69.1%, and 54.9% of medical students considered common antiviral drugs, traditional medicine, and the flu vaccine to be ineffective in preventing COVID-19, respectively. To effectively prevent the transmission of COVID-19, 72.6% of medical students used 3-layer surgical masks, 18.7% relied on hand washing and personal hygiene alone, 73.6% advocated for mask usage by all members of the community, and 47.4% believed in using N95 masks during intubation, suction, bronchoscopy, and cardiopulmonary resuscitation. In terms of information sources, 65.1% of medical students trusted the opinions of doctors and nurses, and 40.6% obtained necessary information about the disease from these healthcare professionals. Conclusions: The basic and clinical knowledge of medical students was at an average level, indicating the need for retraining courses to update their information and impart current knowledge. The normalization of epidemic conditions for medical staff and the students under their supervision was not prevalent among the students. This not only increases the likelihood of individuals contracting the disease multiple times but also poses a potential source of contamination for society. Therefore, conducting educational workshops in this field can significantly impact compliance with health protocols.

A-910823, a squalene-based emulsion adjuvant, enhances robust and broad immune responses of quadrivalent influenza vaccine in ferrets.

Robust and broad protective immunity is typically elicited by co-administration of an adjuvant with vaccine antigens. A-910823, a squalene-based emulsion adjuvant, has been approved in Japan. It effectively enhances the humoral and cellular immunity of S-268019-b, a recombinant COVID-19 vaccine; however, the adjuvant effects of A-910823 on other vaccines, including influenza vaccine, have not been evaluated. Here, a ferret model was employed to investigate the adjuvant effects of A-910823 when combined with split-inactivated quadrivalent influenza vaccine (QIV). We demonstrate that combination of A-910823 with QIV enhances the neutralizing antibody titer and its breadth against non-vaccine strains. Also, the protective efficacy of A-910823-adjuvanted QIV against virus challenge has been confirmed. Of note, QIV combined with A-910823 caused only minor detectable side effects, whereas a significant increase in fever was observed after two doses of mRNA-LNP in ferrets. This study provides information on the effectiveness and safety of A-910823-adjuvanted QIV and suggests the usefulness of the ferret model for evaluating vaccine-induced reactogenicity.

P-1455. Socioeconomic and Regional Impact on Influenza Vaccination in Young Children During the COVID-19 Pandemic

Abstract Background Influenza (flu) vaccination reduces hospitalizations and severe illness, especially in young children particularly vulnerable to complicationsTable 1:Comparison of Influenza Vaccination Rates and Associated Predictors Among American Children Aged 0-5 Years in 2019 and 2022 This table provides an overview of key variables influencing flu vaccination rates among young children, showing changes between 2019 and 2022. It includes data on the total number of children surveyed, vaccination status, average age, gender distribution, educational levels of parents, family income quartiles, ethnic groups with the highest and lowest vaccination rates, insurance coverage, and whether the child had a doctor's visit in the past year. Methods Data from the National Health Interview Survey for 2019 and 2022 were analyzed to assess the impact of parental education, household income, health insurance, and race/ethnicity on flu vaccination rates among U.S. children ≤5 years. Employing logistic regression, Chi-square tests, and Mann-Whitney U tests in STATA, the potential influence of socioeconomic factors on influenza vaccination during the COVID-19 pandemic was evaluated.Table 2:Factors Influencing Influenza Vaccination Rates Among Young Children in the United States, 2019-2022: Results from Logistic Regression Analysis This table summarizes the logistic regression analysis results, presenting odds ratios, 95% confidence intervals, and p-values for predictors influencing influenza vaccination rates among young children aged 0-5 years. The analysis underscores the significant impact of the survey year, child's age, ethnicity, region, parental education, family income, insurance status, and recent healthcare interactions on vaccination likelihood. Results Records for 7636 children in 50 states were reviewed (2858 in 2019 and 4778 in 2022). Flu vaccination rates decreased from 56.02% in 2019 to 46.38% in 2022 (p &amp;lt; 0.001). The decline in flu vaccination rates was most pronounced among younger children, with rates for 2-year-olds reducing from 66.60% to 53.38%, 1-year-olds from 62.95% to 49.03%. and infants from 30.87% to 24.22% (p &amp;lt; 0.001). Insured children were more likely to be vaccinated than uninsured (OR=1.64, p&amp;lt; 0.001). A recent doctor's visit increased the likelihood of receiving a flu vaccine (OR=5.68, p&amp;lt; 0.001). Children from households earning ≥400% of the federal poverty level and those with college or above-educated parents had higher odds of vaccination (OR=1.93, p&amp;lt; 0.001 and OR=1.84, p=0.001, respectively). Significant regional variations in flu vaccination were noted, especially in the Southern U.S. (OR=0.70, p&amp;lt; 0.001). Racial differences were significant, with lower flu vaccination rates among non-Hispanic Black children compared to non-Hispanic Whites (OR=0.70, p&amp;lt; 0.001), while non-Hispanic Asian children exhibited higher flu vaccination rates (OR=1.32, p=0.018). Conclusion The decline in flu vaccination rates among young children during the COVID-19 pandemic highlights the influence of socioeconomic factors, healthcare access, and racial disparities on public health outcomes. Addressing these issues is crucial for improving vaccination rates and reducing influenza's impact on young children. Disclosures All Authors: No reported disclosures