Influenza vaccination in older adults during the COVID-19 pandemic: a population-based study in 133 Brazilian cities. / Vacinação para influenza em idosos na pandemia COVID-19: estudo de base populacional em 133 cidades brasileiras.

Routine immunization during pandemics can be harmed. This study estimated the influenza vaccination coverage in older adults during the COVID-19 through the EPICOVID-19, a population-based study conducted in 133 cities from the 26 Brazilian states and Federal District. We selected 25 census tracts per city, with probability proportional to the tract's size, ten households by census tract, and one random individual interviewed. A total of 8,265 older adults (≥60 years old) were interviewed and asked whether they had been vaccinated against flu in 2020. Vaccination coverage was 82.3% (95% CI: 80.1-84.2) with no difference by gender, age, and region; higher vaccination coverage was observed among the wealthiest (84.7% versus 80.1% in the poorest) and among the more educated (87.3% versus 83.2% less educated); lower coverage among indigenous (56.9% versus > 80% among other ethnic groups). A positive association was identified with the number of comorbidities among men but not among women. Most of the population was vaccinated (97.5%) in the public health system. The private network was chosen mainly in the South by the wealthiest and more educated. Vaccination coverage was seven percentage points lower than the government target (90%), and inequalities should be reversed in future campaigns.

Imunizações de rotina durante pandemias podem ser prejudicadas. Este estudo estimou a cobertura vacinal para influenza em idosos durante a COVID-19 através do EPICOVID-19, inquérito populacional realizado em 133 cidades sentinelas dos 26 estados brasileiros e Distrito Federal. Selecionou-se 25 setores censitários por cidade, amostragem proporcional ao tamanho, dez domicílios por setor e uma pessoa por domicílio, aleatoriamente. O quantitativo de 8.265 idosos (≥ 60 anos) foram entrevistados e responderam se haviam sido vacinados contra gripe em 2020. A cobertura foi 82,3% (IC95% 80,1; 84,2), sem diferenças por sexo, idade ou região. Maiores coberturas ocorreram nos mais ricos (84,7% versus 80,1% nos mais pobres) e nos mais escolarizados (87,3% versus 83,2% nos menos escolarizados). Menor cobertura nos indígenas (56,9% versus coberturas superiores a 80% nos demais grupos étnicos). Houve associação positiva com número de comorbidades entre homens, mas não entre mulheres. A maioria vacinou-se na rede pública (97,5%), sendo a rede privada mais utilizada na região Sul, pelos mais escolarizados e mais ricos. Conclui-se que a cobertura vacinal ficou sete pontos percentuais abaixo da meta governamental (90%), e que desigualdades devem ser revertidas em futuras campanhas.

Seesaw Effect Between COVID-19 and Influenza From 2020 to 2023 in World Health Organization Regions: Correlation Analysis.

BACKGROUND: Seasonal influenza activity showed a sharp decline in activity at the beginning of the emergence of COVID-19. Whether there is an epidemiological correlation between the dynamic of these 2 respiratory infectious diseases and their future trends needs to be explored. OBJECTIVE: We aimed to assess the correlation between COVID-19 and influenza activity and estimate later epidemiological trends. METHODS: We retrospectively described the dynamics of COVID-19 and influenza in 6 World Health Organization (WHO) regions from January 2020 to March 2023 and used the long short-term memory machine learning model to learn potential patterns in previously observed activity and predict trends for the following 16 weeks. Finally, we used Spearman correlation coefficients to assess the past and future epidemiological correlation between these 2 respiratory infectious diseases. RESULTS: With the emergence of the original strain of SARS-CoV-2 and other variants, influenza activity stayed below 10% for more than 1 year in the 6 WHO regions. Subsequently, it gradually rose as Delta activity dropped, but still peaked below Delta. During the Omicron pandemic and the following period, the activity of each disease increased as the other decreased, alternating in dominance more than once, with each alternation lasting for 3 to 4 months. Correlation analysis showed that COVID-19 and influenza activity presented a predominantly negative correlation, with coefficients above -0.3 in WHO regions, especially during the Omicron pandemic and the following estimated period. The diseases had a transient positive correlation in the European region of the WHO and the Western Pacific region of the WHO when multiple dominant strains created a mixed pandemic. CONCLUSIONS: Influenza activity and past seasonal epidemiological patterns were shaken by the COVID-19 pandemic. The activity of these diseases was moderately or greater than moderately inversely correlated, and they suppressed and competed with each other, showing a seesaw effect. In the postpandemic era, this seesaw trend may be more prominent, suggesting the possibility of using one disease as an early warning signal for the other when making future estimates and conducting optimized annual vaccine campaigns.

Broad-spectrum pan-genus and pan-family virus vaccines.

Although the development and clinical application of SARS-CoV-2 vaccines during the COVID-19 pandemic demonstrated unprecedented vaccine success in a short time frame, it also revealed a limitation of current vaccines in their inability to provide broad-spectrum or universal protection against emerging variants. Broad-spectrum vaccines, therefore, remain a dream and challenge for vaccinology. This review will focus on current and future efforts in developing universal vaccines targeting different viruses at the genus and/or family levels, with a special focus on henipaviruses, influenza viruses, and coronaviruses. It is evident that strategies for developing broad-spectrum vaccines will be virus-genus or family specific, and it is almost impossible to adopt a universal approach for different viruses. On the other hand, efforts in developing broad-spectrum neutralizing monoclonal antibodies have been more successful and it is worth considering broad-spectrum antibody-mediated immunization, or "universal antibody vaccine," as an alternative approach for early intervention for future disease X outbreaks.

From COVID-19 Vaccine Hesitancy to Vaccine Acceptance: Results of a Longitudinal Survey.

OBJECTIVES: COVID-19 vaccines are widely available, but uptake is suboptimal. To develop strategies to increase vaccination rates, we sought to (1) characterize adults initially hesitant to be vaccinated for COVID-19 who later received the vaccine and (2) identify factors associated with their vaccination decision. METHODS: In January 2021, we conducted an online survey of US adults via Prolific that assessed vaccination intent, COVID-19-related knowledge and attitudes, and demographic characteristics. In May 2021, we recontacted respondents to assess vaccination status and factors influencing their vaccination decision. We used χ2 statistics and t tests to examine associations between respondents' vaccination status and their characteristics, knowledge, and attitudes. We analyzed reasons for vaccination using thematic analysis. RESULTS: Of 756 initially vaccine-hesitant respondents, 529 (70.0%) completed the follow-up survey. Nearly half of those initially not sure about vaccination (47.3%, 112 of 237) were vaccinated at follow-up, while 21.2% (62 of 292) of those initially planning not to be vaccinated were vaccinated at follow-up. Of those initially not sure, higher educational attainment, greater knowledge of COVID-19, and a doctor's recommendation were associated with vaccination. Of those initially intending not to be vaccinated, male sex, Democratic political affiliation, receipt of an influenza shot within 5 years, being more worried about COVID-19, and having greater COVID-19 knowledge were associated with increased likelihood of being vaccinated. Of 167 respondents who gave reasons for vaccination, protecting oneself and others (59.9%), practical issues (29.9%), social influences (17.4%), and vaccine safety (13.8%) were the main reasons. CONCLUSION: Providing information on the protective value of vaccination, implementing rules that make remaining unvaccinated burdensome, making vaccination easy, and providing social support may influence vaccine-hesitant adults to accept vaccination.

Predictors of COVID-19 Vaccination Among EMS Personnel.

INTRODUCTION: Unvaccinated emergency medical services (EMS) personnel are at increased risk of contracting coronavirus disease 2019 (COVID-19) and potentially transmitting the virus to their families, coworkers, and patients. Effective vaccines for the severe acute respiratory syndrome coronavirus 2 virus exist; however, vaccination rates among EMS professionals remain largely unknown. Consequently, we sought to document vaccination rates of EMS professionals and identify predictors of vaccination uptake. METHODS: We conducted a cross-sectional survey of North Carolina EMS professionals after the COVID-19 vaccines were widely available. The survey assessed vaccination status as well as beliefs regarding COVID-19 illness and vaccine effectiveness. Prediction of vaccine uptake was modeled using logistic regression. RESULTS: A total of 860 EMS professionals completed the survey, of whom 74.7% reported receiving the COVID-19 vaccination. Most respondents believed that COVID-19 is a serious threat to the population, that they are personally at higher risk of infection, that vaccine side effects are outweighed by illness prevention, and the vaccine is safe and effective. Despite this, only 18.7% supported mandatory vaccination for EMS professionals. Statistically significant differences were observed between the vaccinated and unvaccinated groups regarding vaccine safety and effectiveness, recall of employer vaccine recommendation, perceived risk of infection, degree of threat to the population, and trust in government to take actions to limit the spread of disease. Unvaccinated respondents cited reasons such as belief in personal health and natural immunity as protectors against infection, concerns about vaccine safety and effectiveness, inadequate vaccine knowledge, and lack of an employer mandate for declining the vaccine. Predictors of vaccination included belief in vaccine safety (odds ratio [OR] 5.5, P=<0.001) and effectiveness (OR 4.6, P=<0.001); importance of vaccination to protect patients (OR 15.5, P=<0.001); perceived personal risk of infection (OR 1.8, P=0.04); previous receipt of influenza vaccine (OR 2.5, P=0.003); and sufficient knowledge to make an informed decision about vaccination (OR 2.4, P=0.024). CONCLUSION: In this survey of EMS professionals, over a quarter remained unvaccinated for COVID-19. Given the identified predictors of vaccine acceptance, EMS systems should focus on countering misinformation through employee educational campaigns as well as on developing policies regarding workforce immunization requirements.

Influenza and pertussis vaccine coverage in pregnancy in Australia, 2016-2021.

Vaccination in pregnancy is the best strategy to reduce complications from influenza or pertussis infection in infants who are too young to be protected directly from vaccination. Pregnant women are also at risk of influenza complications preventable through antenatal vaccination. Both vaccines are funded under the National Immunisation Program for pregnant women in Australia, but coverage is not routinely reported nationally. We reviewed all reported Australian maternal influenza and pertussis vaccine coverage data for the period 2016-2021, to identify gaps and information needs. Maternal influenza vaccine coverage was suboptimal at < 58% for 2016-2018, with higher coverage of 62-75% reported in two states (Victoria and Western Australia) for 2019-2021. Maternal pertussis vaccine coverage from 2016 was generally higher than for influenza at > 70%, with the highest jurisdictional coverage of 89% reported in Western Australia in 2020. Vaccination rates were often suboptimal among First Nations pregnant women and up to 20% lower than among non-First Nations Australian women; while data were limited, coverage was low among culturally and linguistically diverse women and among women of lower socio-economic status. Jurisdictional perinatal data collections were the best source of information on antenatal vaccine coverage but were only available for a minority of the population; a nationally consistent systematic approach is lacking. Timely and comprehensive data are needed to provide feedback to improve maternal vaccination coverage, particularly among groups with higher risk and/or low uptake, and as new vaccines are recommended, including COVID-19 vaccination.

Determinants of Vaccination and Willingness to Vaccinate against COVID-19 among Pregnant and Postpartum Women during the Third Wave of the Pandemic: A European Multinational Cross-Sectional Survey.

With COVID-19 vaccination hesitancy at around 50% in the obstetric population, it is critical to identify which women should be addressed and how. Our study aimed to assess COVID-19 vaccination willingness among pregnant and postpartum women in Europe and to investigate associated determinants. This study was a cross-sectional, web-based survey conducted in Belgium, Norway, Switzerland, The Netherlands, and United Kingdom (UK) in June-August 2021. Among 3194 pregnant women, the proportions of women vaccinated or willing to be vaccinated ranged from 80.5% in Belgium to 21.5% in Norway. The associated characteristics were country of residence, chronic illness, history of flu vaccine, trimester of pregnancy, belief that COVID-19 is more severe during pregnancy, and belief that the COVID-19 vaccine is effective and safe during pregnancy. Among 1659 postpartum women, the proportions of women vaccinated or willing to be vaccinated ranged from 86.0% in the UK to 58.6% in Switzerland. The associated determinants were country of residence, chronic illness, history of flu vaccine, breastfeeding, and belief that the COVID-19 vaccine is safe during breastfeeding. Vaccine hesitancy in the obstetric population depends on medical history and especially on the opinion that the vaccine is safe and on the country of residence.

Acceptance of recommended vaccinations during pregnancy: a cross-sectional study in Southern Italy.

Background: Vaccine administration is a recommended, safe, and effective measure to protect pregnant women against vaccine-preventable diseases (VPDs). Despite available guidance, maternal immunization rates for vaccination against influenza and with the reduced antigen content tetanus-diphtheria-acellular pertussis vaccine (Tdap) in Italy remain incredibly low. The primary goal of the study was to explore what Italian pregnant women knew about VPDs and immunization during pregnancy and what factors affected their decision to be vaccinated. Methods: This cross-sectional study took place between October 2021 and April 2022 in the Southern part of Italy. All consecutive pregnant women, from those attending the selected facilities on randomly selected days, were approached to request participation. The inclusion criteria for participation were age ≥18 years, the ability to understand, speak, and read Italian, and being pregnant at any gestational age. The questionnaire, using a combination of checkboxes and free text answers, consisted of 32 items divided into five parts and lasted ~10 min. Results: The results showed that 61% knew that the influenza vaccine is recommended and 48.7% knew that influenza could be risky during pregnancy; 74.1% wrongly reported that the Measles-Mumps-Rubella (MMR) vaccine is recommended during pregnancy. Seven out of 10 pregnant women believed that strong evidence supported the safety of vaccinations during pregnancy, and more than half (55.6%) thought they were at increased risk of severe illness with COVID-19. Women in the sample believed that vaccines received during pregnancy pose a risk of adverse events to the unborn child with a median value of 6 (IQR 3-9), on a scale ranging from 1 to 10. Similarly, the fear of contracting pertussis and influenza during pregnancy showed a median value of 6 (IQR 3-9) and 5 (IQR 3-8), respectively. Only 21.1% and 36.5% of women received influenza and Tdap vaccines during pregnancy. Conclusion: Unrealistic risk perception with a negative attitude toward vaccines in pregnancy and a low percentage of vaccinated pregnant women confirm the urgency of training women to make informed choices to increase overall vaccine uptake.

COVID-19 vaccines and the pandemic: lessons learnt for other neglected diseases and future threats.

Through the experiences gained by accelerating new vaccines for both Ebola virus infection and COVID-19 in a public health emergency, vaccine development has benefited from a 'multiple shots on goal' approach to new vaccine targets. This approach embraces simultaneous development of candidates with differing technologies, including, when feasible, vesicular stomatitis virus or adenovirus vectors, messenger RNA (mRNA), whole inactivated virus, nanoparticle and recombinant protein technologies, which led to multiple effective COVID-19 vaccines. The challenge of COVID-19 vaccine inequity, as COVID-19 spread globally, created a situation where cutting-edge mRNA technologies were preferentially supplied by multinational pharmaceutical companies to high-income countries while low and middle-income countries (LMICs) were pushed to the back of the queue and relied more heavily on adenoviral vector, inactivated virus and recombinant protein vaccines. To prevent this from occurring in future pandemics, it is essential to expand the scale-up capacity for both traditional and new vaccine technologies at individual or simultaneous hubs in LMICs. In parallel, a process of tech transfer of new technologies to LMIC producers needs to be facilitated and funded, while building LMIC national regulatory capacity, with the aim of several reaching 'stringent regulator' status. Access to doses is an essential start but is not sufficient, as healthcare infrastructure for vaccination and combating dangerous antivaccine programmes both require support. Finally, there is urgency to establish an international framework through a United Nations Pandemic Treaty to promote, support and harmonise a more robust, coordinated and effective global response.

Facilitators and barriers for vaccination in patients with inflammatory rheumatic musculoskeletal diseases: a prospective cohort study.

INTRODUCTION: To identify facilitators and barriers towards vaccination in general and specifically against pneumococci, influenza and SARS-CoV-2 in patients with rheumatic musculoskeletal diseases (RMD). METHODS: Between February and April 2021, consecutive patients with RMD were asked to complete a structured questionnaire on general knowledge about vaccination, personal attitudes and perceived facilitators and barriers towards vaccination. General facilitators (n=12) and barriers (n=15) and more specific ones for vaccination against pneumococci, influenza and SARS-CoV-2 were assessed. Likert scales had four response options: from 1 (completely disagree) to 4 (completely agree). Patient and disease characteristics, their vaccination records and attitudes towards vaccination against SARS-CoV-2 were assessed. RESULTS: 441 patients responded to the questionnaire. Knowledge about vaccination was decent in ≥70% of patients, but <10% of patients doubted its effectiveness. Statements on facilitators were generally more favourable than on barriers. Facilitators for SARS-CoV-2 vaccination were not different from vaccination in general. Societal and organisational facilitators were more often named than interpersonal or intrapersonal facilitators. Most patients indicated that recommendations of their healthcare professional would encourage them to be vaccinated-without preference for general practitioner or rheumatologists. There were more barriers towards SARS-CoV-2 vaccination than to vaccination in general. Intrapersonal issues were most frequently reported as a barrier. Statistically significant differences in response patterns to nearly all barriers between patients classified as definitely willing, probably willing and unwilling to receive SARS-CoV-2 vaccines were noted. DISCUSSION: Facilitators towards vaccination were more important than barriers. Most barriers against vaccination were intrapersonal issues. Societal facilitators identified support strategies in that direction.

Prior SARS-CoV-2 infection and COVID-19 vaccine effectiveness against outpatient illness during widespread circulation of SARS-CoV-2 Omicron variant, US Flu VE network.

BACKGROUND: We estimated combined protection conferred by prior SARS-CoV-2 infection and COVID-19 vaccination against COVID-19-associated acute respiratory illness (ARI). METHODS: During SARS-CoV-2 Delta (B.1.617.2) and Omicron (B.1.1.529) variant circulation between October 2021 and April 2022, prospectively enrolled adult patients with outpatient ARI had respiratory and filter paper blood specimens collected for SARS-CoV-2 molecular testing and serology. Dried blood spots were tested for immunoglobulin-G antibodies against SARS-CoV-2 nucleocapsid (NP) and spike protein receptor binding domain antigen using a validated multiplex bead assay. Evidence of prior SARS-CoV-2 infection also included documented or self-reported laboratory-confirmed COVID-19. We used documented COVID-19 vaccination status to estimate vaccine effectiveness (VE) by multivariable logistic regression by prior infection status. RESULTS: Four hundred fifty-five (29%) of 1577 participants tested positive for SARS-CoV-2 infection at enrollment; 209 (46%) case-patients and 637 (57%) test-negative patients were NP seropositive, had documented previous laboratory-confirmed COVID-19, or self-reported prior infection. Among previously uninfected patients, three-dose VE was 97% (95% confidence interval [CI], 60%-99%) against Delta, but not statistically significant against Omicron. Among previously infected patients, three-dose VE was 57% (CI, 20%-76%) against Omicron; VE against Delta could not be estimated. CONCLUSIONS: Three mRNA COVID-19 vaccine doses provided additional protection against SARS-CoV-2 Omicron variant-associated illness among previously infected participants.

Healthcare professionals' beliefs regarding influenza vaccination: What has COVID-19 changed?

Background: Influenza poses a potential public health threat among healthcare professionals since an infected healthcare professional can spread the virus to patients at higher risk as well as his/her own family members and colleagues. Annual influenza vaccination is the most effective way to protect HCPs. Aim: This study was conducted to determine whether demand for and beliefs about influenza vaccination have changed among healthcare professionals in the COVID-19 era and the factors that might have influenced them in the early phase of the pandemic when COVID-19 vaccines were eagerly awaited. Patients and Methods: This observational descriptive study was conducted between November 16, and December 15, 2020. A total of 317 healthcare professionals completed an online survey. Bivariate analysis and binary logistic regression analysis were performed. Results: Nineteen (6.0%) healthcare professionals were regularly vaccinated against influenza every year, and 199 (62.8%) had never been vaccinated. During the 2019-2020 season, 30 (9.5%) participants had been vaccinated and the proportion desiring to be vaccinated against influenza during the 2020-2021 season was 49.8% (n = 158). The results revealed that those with chronic diseases, those who believed they had adequate information about influenza vaccination and those who believed healthcare professionals should be vaccinated against influenza regularly every year, respectively, had 3.5 times, 4.7 times, and 11 times higher vaccination rates. Conclusion: Although the proportion of healthcare professionals with the intention to be vaccinated for influenza increased with the COVID-19 pandemic, it is still not high enough. Influenza vaccination rates should be promoted by in-service training programs.

Changes in the urinary proteome before and after quadrivalent influenza vaccine and COVID-19 vaccination.

The proteome of urine samples from quadrivalent influenza vaccine cohort were analyzed with self-contrasted method. Significantly changed urine protein at 24 hours after vaccination was enriched in immune-related pathways, although each person's specific pathways varied. We speculate that this may be because different people have different immunological backgrounds associated with influenza. Then, urine samples were collected from several uninfected SARS-CoV-2 young people before and after the first, second, and third doses of the COVID-19 vaccine. The differential proteins compared between after the second dose (24h) and before the second dose were enriched in pathways involving in multicellular organismal process, regulated exocytosis and immune-related pathways, indicating no first exposure to antigen. Surprisingly, the pathways enriched by the differential urinary protein before and after the first dose were similar to those before and after the second dose. It is inferred that although the volunteers were not infected with SARS-CoV-2, they might have been exposed to other coimmunogenic coronaviruses. Two to four hours after the third vaccination, the differentially expressed protein were also enriched in multicellular organismal process, regulated exocytosis and immune-related pathways, indicating that the immune response has been triggered in a short time after vaccination. Multicellular organismal process and regulated exocytosis after vaccination may be a new indicator to evaluate the immune effect of vaccines. Urinary proteome is a terrific window to monitor the changes in human immune function.

Comparing the Use of a Mobile App and a Web-Based Notification Platform for Surveillance of Adverse Events Following Influenza Immunization: Randomized Controlled Trial.

BACKGROUND: Vaccine safety surveillance is a core component of vaccine pharmacovigilance. In Canada, active, participant-centered vaccine surveillance is available for influenza vaccines and has been used for COVID-19 vaccines. OBJECTIVE: The objective of this study is to evaluate the effectiveness and feasibility of using a mobile app for reporting participant-centered seasonal influenza adverse events following immunization (AEFIs) compared to a web-based notification system. METHODS: Participants were randomized to influenza vaccine safety reporting via a mobile app or a web-based notification platform. All participants were invited to complete a user experience survey. RESULTS: Among the 2408 randomized participants, 1319 (54%) completed their safety survey 1 week after vaccination, with a higher completion rate among the web-based notification platform users (767/1196, 64%) than among mobile app users (552/1212, 45%; P<.001). Ease-of-use ratings were high for the web-based notification platform users (99% strongly agree or agree) and 88.8% of them strongly agreed or agreed that the system made reporting AEFIs easier. Web-based notification platform users supported the statement that a web-based notification-only approach would make it easier for public health professionals to detect vaccine safety signals (91.4%, agreed or strongly agreed). CONCLUSIONS: Participants in this study were significantly more likely to respond to a web-based safety survey rather than within a mobile app. These results suggest that mobile apps present an additional barrier for use compared to the web-based notification-only approach. TRIAL REGISTRATION: ClinicalTrials.gov NCT05794113; https://clinicaltrials.gov/show/NCT05794113.

Immune interference in effectiveness of influenza and COVID-19 vaccination.

Vaccines are known to function as the most effective interventional therapeutics for controlling infectious diseases, including polio, smallpox, rabies, tuberculosis, influenza and SARS-CoV-2. Smallpox has been eliminated completely and polio is almost extinct because of vaccines. Rabies vaccines and Bacille Calmette-Guérin (BCG) vaccines could effectively protect humans against respective infections. However, both influenza vaccines and COVID-19 vaccines are unable to eliminate these two infectious diseases of their highly variable antigenic sites in viral proteins. Vaccine effectiveness (VE) could be negatively influenced (i.e., interfered with) by immune imprinting of previous infections or vaccinations, and repeated vaccinations could interfere with VE against infections due to mismatch between vaccine strains and endemic viral strains. Moreover, VE could also be interfered with when more than one kind of vaccine is administrated concomitantly (i.e., co-administrated), suggesting that the VE could be modulated by the vaccine-induced immunity. In this review, we revisit the evidence that support the interfered VE result from immune imprinting or repeated vaccinations in influenza and COVID-19 vaccine, and the interference in co-administration of these two types of vaccines is also discussed. Regarding the development of next-generation COVID-19 vaccines, the researchers should focus on the induction of cross-reactive T-cell responses and naive B-cell responses to overcome negative effects from the immune system itself. The strategy of co-administrating influenza and COVID-19 vaccine needs to be considered more carefully and more clinical data is needed to verify this strategy to be safe and immunogenic.

Evaluation of missed influenza vaccination opportunities in the emergency department.

BACKGROUND: Seasonal influenza is associated with significant healthcare resource utilization. An estimated 490,000 hospitalizations and 34,000 deaths were attributed to influenza during the 2018-2019 season. Despite robust influenza vaccination programs in both the inpatient and outpatient setting, the emergency department (ED) represents a missed opportunity to vaccinate patients at high risk for influenza who do not have access to routine preventive care. Feasibility and implementation of ED-based influenza vaccination programs have been previously described but have stopped short of describing the predicted health resource impact. The goal of our study was to describe the potential impact of an influenza vaccination program in an urban adult emergency department population using historic patient data. METHODS: This was a retrospective study of all encounters within a tertiary care hospital-based ED and three freestanding EDs during influenza season (defined as October 1 - April 30) over a two-years, 2018-2020. Data was obtained from the electronic medical record (EPIC®). All ED encounters during the study period were screened for inclusion using ICD 10 codes. Patients with a confirmed positive influenza test and no documented influenza vaccine for the current season were reviewed for any ED encounter at least 14 days prior to the influenza-positive encounter and during the concurrent influenza season. These ED visits were deemed a missed opportunity to provide vaccination and potentially prevent the influenza-positive encounter. Healthcare resource utilization, including subsequent ED encounters and inpatient admissions, were evaluated for patients with a missed vaccination opportunity. RESULTS: A total of 116,140 ED encounters occurred during the study and were screened for inclusion. Of these, 2115 were influenza-positive encounters, which represented 1963 unique patients. There were 418 patients (21.3%) that had a missed opportunity to be vaccinated during an ED encounter at least 14 days prior to the influenza-positive encounter. Of those with a missed vaccination opportunity, 60 patients (14.4%) had subsequent influenza-related encounters, including 69 ED visits and 7 inpatient admissions. CONCLUSION: Patients presenting to the ED with influenza frequently had opportunities to be vaccinated during prior ED encounters. An ED-based influenza vaccination program could potentially reduce influenza-related burden on healthcare resources by preventing future influenza-related ED encounters and hospitalizations.

Immune Response to Seasonal Influenza Vaccination in Multiple Sclerosis Patients Receiving Cladribine.

Cladribine has been approved for the treatment of multiple sclerosis (MS) and its administration results in a long-lasting depletion of lymphocytes. As lymphopenia is known to hamper immune responses to vaccination, we evaluated the immunogenicity of the influenza vaccine in patients undergoing cladribine treatment at different stages vs. controls. The antibody response in 90 cladribine-treated MS patients was prospectively compared with 10 control subjects receiving platform immunotherapy (NCT05019248). Serum samples were collected before and six months after vaccination. Response to vaccination was determined by the hemagglutination-inhibition test. Postvaccination seroprotection rates against influenza A were comparable in cladribine-treated patients and controls (H1N1: 94.4% vs. 100%; H3N2: 92.2% vs. 90.0%). Influenza B response was lower in the cladribine cohort (61.1% vs. 80%). The increase in geometric mean titers was lower in the cladribine group vs. controls (H1N1: +98.5 vs. +188.1; H3N2: +225.3 vs. +300.0; influenza B: +40.0 vs. +78.4); however, titers increased in both groups for all strains. Seroprotection was achieved irrespective of vaccination timing and lymphocyte subset counts at the time of vaccination in the cladribine cohort. To conclude, cladribine-treated MS patients can mount an adequate immune response to influenza independently of treatment duration and time interval to the last cladribine administration.