Vaccine: XPub Date : 2025-08-26DOI: 10.1016/j.jvacx.2025.100711
Jimmy R. Lopez , Otto G. Vanderkooi , James D. Kellner , Louis Valiquette , Gaston De Serres , Karina A. Top , Jennifer Isenor , Matthew P. Muller , Monika Naus , Julie A. Bettinger , for the Canadian Immunization Research Network Investigators
{"title":"The Canadian National Vaccine Safety (CANVAS) network: Cross-sectional analysis of seasonal influenza vaccine safety in children during the 2013/2014 to 2019/2020 influenza seasons","authors":"Jimmy R. Lopez , Otto G. Vanderkooi , James D. Kellner , Louis Valiquette , Gaston De Serres , Karina A. Top , Jennifer Isenor , Matthew P. Muller , Monika Naus , Julie A. Bettinger , for the Canadian Immunization Research Network Investigators","doi":"10.1016/j.jvacx.2025.100711","DOIUrl":"10.1016/j.jvacx.2025.100711","url":null,"abstract":"<div><div>The Canadian National Vaccine Safety (CANVAS) network is a participant-centered, active surveillance system that assesses vaccine safety across Canada. Our study examined the safety profile of influenza vaccines administered to children during seven consecutive influenza seasons, from 2013/2014 to 2019/2020, to establish a baseline for health events in vaccinated and unvaccinated children before the COVID-19 pandemic. Data were collected using an online survey after a 7-day period for vaccinated and unvaccinated participants. Descriptive and inferential analyses explored the association between the influenza vaccine and health events, including associated symptoms. The proportion of health events were comparable in vaccinated and unvaccinated children. Adjusted regression models identified no statistical difference in the occurrence of health events assessed. The most frequently reported symptoms were fever, gastrointestinal symptoms (i.e., nausea/vomiting/diarrhea), and cough. Our findings observed low incidence of health events in both vaccinated and unvaccinated groups in this multi-year study.</div></div>","PeriodicalId":43021,"journal":{"name":"Vaccine: X","volume":"26 ","pages":"Article 100711"},"PeriodicalIF":2.2,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145003899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vaccine: XPub Date : 2025-08-23DOI: 10.1016/j.jvacx.2025.100709
Brenda Aline Maya Badillo , Diana Laura Hernández García , Rodrigo Armando Moreno García , Guillermo Orta Pineda , Carlos Javier Alcázar Ramiro , Juana Castillo Castillo , Mario Solís Hernández , Roberto Navarro López , Armando García López
{"title":"H5N1 highly pathogenic avian influenza vaccination: Seroresponse of mexican poultry in the 2022–2024","authors":"Brenda Aline Maya Badillo , Diana Laura Hernández García , Rodrigo Armando Moreno García , Guillermo Orta Pineda , Carlos Javier Alcázar Ramiro , Juana Castillo Castillo , Mario Solís Hernández , Roberto Navarro López , Armando García López","doi":"10.1016/j.jvacx.2025.100709","DOIUrl":"10.1016/j.jvacx.2025.100709","url":null,"abstract":"<div><div>Since 2021, the activity and impact of the highly pathogenic H5N1 avian influenza virus have intensified worldwide, causing high mortality in wild birds and birds while also infecting various wild and domestic mammals and humans. Particularly, the severe impact on commercial poultry farming has prompted various countries to implement control and mitigation plans to address the damage caused by these viruses. In Mexico, the implementation of vaccination was part of the comprehensive strategies to prevent and control highly pathogenic H5N1 avian influenza outbreaks. For this reason, this work aimed to compare antibody levels in production birds before and after vaccination, examining seroconversion and seroprotection after vaccination in two time periods. Serum samples were taken before and after vaccination in 573 Poultry Production Units during the first vaccination period and 205 Poultry Production Units during the second period across various Mexican states. These samples, later, underwent hemagglutination inhibition tests. With the results obtained from serology, comparisons of medians, calculations of seroconversion and seroprotection, as well as logistic regression analysis were performed. As expected, vaccination led to a statistically higher immune response in birds in most of Mexico's states. However, seroconversion and seroprotection rates remained below 80 % during the first evaluation period. Progenitors and commercial posture birds showed better immune responses to vaccination, particularly with vaccines developed through reverse genetics. These results provide valuable insights into the immune response of Mexican domestic birds under the national strategic plan to control the highly pathogenic influenza A H5N1 virus emergency, which will set a precedent to improve the prevention and control of future outbreaks.</div></div>","PeriodicalId":43021,"journal":{"name":"Vaccine: X","volume":"26 ","pages":"Article 100709"},"PeriodicalIF":2.2,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144917767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vaccine: XPub Date : 2025-08-21DOI: 10.1016/j.jvacx.2025.100710
Caitriona Murphy , Mike Y.W. Kwan , Eunice L.Y. Chan , Joshua S.C. Wong , Sheena G. Sullivan , Malik Peiris , Benjamin J. Cowling , So-Lun Lee
{"title":"Influenza vaccine effectiveness against hospitalizations associated with influenza a in Hong Kong children aged 9 months to 17 years, 2024/25","authors":"Caitriona Murphy , Mike Y.W. Kwan , Eunice L.Y. Chan , Joshua S.C. Wong , Sheena G. Sullivan , Malik Peiris , Benjamin J. Cowling , So-Lun Lee","doi":"10.1016/j.jvacx.2025.100710","DOIUrl":"10.1016/j.jvacx.2025.100710","url":null,"abstract":"<div><div>Influenza began circulating in Hong Kong in mid-December 2024. As of 12 March 2025, 1279 children were enrolled in a prospective test negative study for influenza vaccine effectiveness (VE). Among 209 influenza<strong>-</strong>positive cases, 71 % had influenza A(H1N1), 11 % had influenza A(H3N2), 3 % had influenza A with unknown subtype, and 15 % had influenza B. Among the test-negative controls, 53 % had received influenza vaccination since August 2024. End of the winter season VE estimates against hospitalization associated with influenza A(H1N1) was 64.8 % (95 % CI: 38.1 % to 80.3 %) and for influenza A(H3N2) was 59.9 % (95 % CI: −42.0 % to 89.6 %). These findings indicate that influenza vaccination provided protection against hospitalization for influenza A(H1N1) and A(H3N2) in children, highlighting the importance of continued vaccination efforts in Hong Kong.</div></div>","PeriodicalId":43021,"journal":{"name":"Vaccine: X","volume":"26 ","pages":"Article 100710"},"PeriodicalIF":2.2,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144889946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vaccine: XPub Date : 2025-08-19DOI: 10.1016/j.jvacx.2025.100708
Matilde Zornoza-Moreno , Antonio Iofrío de Arce , Jaime J. Pérez-Martín
{"title":"Attitudes and satisfaction of healthcare professionals towards paediatric influenza vaccination in Spain: A follow-up study","authors":"Matilde Zornoza-Moreno , Antonio Iofrío de Arce , Jaime J. Pérez-Martín","doi":"10.1016/j.jvacx.2025.100708","DOIUrl":"10.1016/j.jvacx.2025.100708","url":null,"abstract":"<div><h3>Background</h3><div>The Region of Murcia was one the first Spanish regions to implement a universal influenza vaccination campaign for children of 6–59 months during the 2022–2023 season. The main goal of the study was to assess the healthcare professionals (HCPs) attitudes and satisfaction with the second paediatric influenza vaccination campaign in the Region of Murcia, the 2023–2024, and to compare the results with those from the first campaign.</div></div><div><h3>Methods</h3><div>Cross-sectional, descriptive study carried out during the 2023–2024 vaccination season using an ad-hoc questionnaire to collect information on HCPs (nurses and doctors) attitudes towards influenza vaccination.</div></div><div><h3>Results</h3><div>Overall, participating HCPs considered that vaccination against influenza in children of 6–59 months was important or very important, with no differences between professional groups, regardless of their own vaccination status. The ease of administration and the general use of the intranasal (LAIV) and intramuscular (IIV) vaccines was good or very good. A higher score of LAIV's general experience was obtained for the 2023–2024 campaign compared with the 2022–2023 campaign (4.7 vs 4.5, <em>p</em> = 0.006). The score for IIV did not change between campaigns (4.0 vs 4.0, <em>p</em> = 0.98). Of all HCPs involved in the 2023–2024 campaign a higher proportion considered that the presence of a doctor was advisable at school vaccination, but not essential compared with the previous one (54.1 % vs 44.7 %, <em>p</em> <em><</em> <em>0.001</em>).</div></div><div><h3>Conclusions</h3><div>Influenza vaccination campaign in the Region of Murcia is highly supported by nurses and doctors. The experience gained during the school vaccination makes vaccination teams feel more confident without a doctor.</div></div>","PeriodicalId":43021,"journal":{"name":"Vaccine: X","volume":"26 ","pages":"Article 100708"},"PeriodicalIF":2.2,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144894772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vaccine: XPub Date : 2025-08-18DOI: 10.1016/j.jvacx.2025.100707
Sylvia Iasulaitis , Alan Demetrius Baria Valejo , Leonardo Ribeiro dos Santos
{"title":"The influence of partisanship on the roots of anti-vaccine attitudes in the context of the COVID-19 pandemic","authors":"Sylvia Iasulaitis , Alan Demetrius Baria Valejo , Leonardo Ribeiro dos Santos","doi":"10.1016/j.jvacx.2025.100707","DOIUrl":"10.1016/j.jvacx.2025.100707","url":null,"abstract":"<div><div>This study identifies the underlying drivers of vaccine hesitancy by analyzing political factors, perceptions of vaccine safety, socioeconomic characteristics, and communication variables. We created a partisanship score using supervised machine learning algorithms with the random forest method to assess the influence of political orientations on the roots of COVID-19 vaccine rejection attitudes. This score was then tested empirically using sociodemographic data from a public opinion survey conducted with a sample of the Brazilian population. Based on the weight of evidence (WoE), the attribute relevance analysis revealed key characteristics of citizens who rejected the COVID-19 vaccine in Brazil, highlighting perceptions of vaccine safety and political variables. The data showed that citizens more loyal to then-president Jair Bolsonaro, a vocal vaccine skeptic, were less likely to get vaccinated. They also demonstrated higher perceptions of vaccine-related risks and were more prone to believing in conspiracy theories and misinformation surrounding the vaccine. The methodology developed in this study can be applied to other populations globally to better understand the roots of anti-vaccine attitudes, particularly the influence of political factors.</div></div>","PeriodicalId":43021,"journal":{"name":"Vaccine: X","volume":"26 ","pages":"Article 100707"},"PeriodicalIF":2.2,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144879990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vaccine: XPub Date : 2025-08-18DOI: 10.1016/j.jvacx.2025.100705
Luciana de Souza Fernandes , Carine Ribeiro Pessoa , Roberto Sousa Dias , Cynthia Canedo da Silva , Sérgio Oliveira de Paula
{"title":"Activation of cellular immune responses using a dengue tetravalent subunit DNA vaccine candidate with different cytokines as adjuvants","authors":"Luciana de Souza Fernandes , Carine Ribeiro Pessoa , Roberto Sousa Dias , Cynthia Canedo da Silva , Sérgio Oliveira de Paula","doi":"10.1016/j.jvacx.2025.100705","DOIUrl":"10.1016/j.jvacx.2025.100705","url":null,"abstract":"<div><div>Dengue remains a critical public health issue in endemic areas, with four co-circulating serotypes (DENV-1–4) and no widely accessible vaccine in Brazil. DNA vaccines offer logistical and cost advantages, and cytokine adjuvants may enhance immunogenicity. We engineered a tetravalent DNA vaccine encoding EDIII from all four DENV serotypes in the pVAX1 vector. To improve immune response, plasmids encoding GM-CSF, IL-7, and IL-15 were co-administered. Antigen expression was confirmed <em>via</em> PCR, western blot, and immunofluorescence. Immunogenicity was assessed using lymphoproliferation assays, TNF/IL-10 cytokine profiling, flow cytometry for memory T-cell phenotyping, and plaque reduction neutralization tests (PRNT). EDIII expression was confirmed for all four serotypes. Co-administration with GM-CSF or IL-15 increased splenocyte proliferation. Cytokine analysis showed variable results with Th1-skewed responses in IL-7 and GM-CSF groups, while IL-15 induced a Th2-biased profile. Flow cytometry revealed that GM-CSF + IL-15 most effectively expanded central memory and naïve CD4+ and CD8+ T cells. PRNT demonstrated neutralizing activity against DENV-1, DENV-3, and DENV-4, but no neutralization of DENV-2. This tetravalent DNA vaccine elicited modest antigen-specific humoral and cellular responses. GM-CSF and IL-15 improved T-cell memory phenotypes, although the absence of DENV-2 neutralization highlights the need for further optimization. Our results inform us of the difficulties in using immune modulators as genetic adjuvants for DNA vaccine design.</div></div>","PeriodicalId":43021,"journal":{"name":"Vaccine: X","volume":"26 ","pages":"Article 100705"},"PeriodicalIF":2.2,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144879989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Safety and immunogenicity of inactivated Zika virus vaccine by gamma irradiation","authors":"Pumin Sintara , Puttawat Suphaprueksapong , Suwimol Jetawattana , Witthawat Wiriyarat , Yada Akkhawattanangkul , Komgrid Charngkaew , Nusara Chomanee , Jantip Saelee , Artit Wongsa , Thongkoon Priengprom , Boonrat Tassaneetrithep","doi":"10.1016/j.jvacx.2025.100706","DOIUrl":"10.1016/j.jvacx.2025.100706","url":null,"abstract":"<div><div>Developing the Zika virus (ZIKV) vaccine remains a critical global public health need. This study assessed the safety and immunogenicity of gamma-irradiated Thai ZIKV isolate. Inactivation was confirmed by serial passaging and detection of viral replication using RT-PCR, which demonstrated complete loss of infectivity in ZIKV irradiated with 25 and 50 kGy. Western blotting confirmed that irradiation preserved viral envelope protein antigenicity. BALB/c mice were subcutaneously immunized twice with 25 kGy-irradiated ZIKV, either alone or with alum adjuvant, at two-week intervals. No mortality or local reactions were observed in any group of mice. Antigen-specific IgG and neutralizing antibody titers were measured by ELISA and focus reduction neutralization test, respectively. T cell responses were assessed via intracellular IFN-γ and TNF-α staining by flow cytometry. The irradiated vaccine induced ZIKV-specific antibody and cytokine-producing T cell responses; however, neutralizing antibody titers were low. Mice immunized with irradiated ZIKV combined with alum adjuvant had higher ZIKV-specific antibody titers and T cells producing IFN-γ or TNF-α than those without adjuvant, though differences were not statistically significant. Although the viral integrity and antigenicity remained unchanged, these findings demonstrate that gamma-irradiated ZIKV is non-infectious and immunogenic in mice, supporting its safety profile and the potential for further optimization in future dose-ranging and efficacy studies.</div></div>","PeriodicalId":43021,"journal":{"name":"Vaccine: X","volume":"26 ","pages":"Article 100706"},"PeriodicalIF":2.2,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144863327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Does behaviour matters the most in improving urban immunization coverage: exploring behavioural barriers in northern states of India","authors":"Pritu Dhalaria , Ayushi Agrawal , Jaideep Kumar , Ajeet Kumar Singh , Ashish Maurya , Syed Hassan , Bhupendra Tripathi , Arindam Ray , Sanjay Kapur","doi":"10.1016/j.jvacx.2025.100702","DOIUrl":"10.1016/j.jvacx.2025.100702","url":null,"abstract":"<div><h3>Background</h3><div>Immunization is a crucial public health achievement, yet achieving equitable coverage remains challenging in countries like India. Despite India's notable progress in its Universal Immunization Program (UIP), urban-rural discrepancies persist, especially in densely populated states like Bihar and Uttar Pradesh, with urban areas experiencing slower improvement in coverage.</div></div><div><h3>Data & methodology</h3><div>This study, conducted in Bihar and Uttar Pradesh, aimed to explore behavioural and social determinants affecting immunization uptake in urban areas. Based on the WHO's Behavioural and Social Drivers of Vaccination (BeSD) model, a comprehensive baseline situation analysis, including 34 in-depth interviews and 27 focus group discussions, was conducted in 12 districts of Bihar and Uttar Pradesh. The assessment covered the perceptions of caregivers, healthcare providers, and key immunization stakeholders.</div></div><div><h3>Results</h3><div>Findings are categorized within the BeSD model's four domains: Thinking and Feeling, Social Processes, Motivation, and Practical Issues. In the thinking and feeling domain, perceived understanding gaps, the need for awareness, and the role of mass media and social networks emerged as key themes. Social processes illuminate gender dynamics, the dominance of decision-making by male and elderly members, and the impact of domestic violence on vaccination choices. Motivational factors include concerns about vaccine quality, fear of adverse events, and the influence of religious leaders. Practical issues encompass distrust of healthcare personnel, the timing of vaccination sessions, and infrastructural.</div></div><div><h3>Conclusion</h3><div>The study reveals multifaceted challenges, highlighting the need for targeted urban-specific strategies to address social and behavioural barriers, enhance awareness, and improve infrastructure in urban immunization programs.</div></div>","PeriodicalId":43021,"journal":{"name":"Vaccine: X","volume":"26 ","pages":"Article 100702"},"PeriodicalIF":2.2,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144809758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vaccine: XPub Date : 2025-08-07DOI: 10.1016/j.jvacx.2025.100700
Sinead E. Morris , Sarabeth M. Mathis , Jessie R. Chung , Brendan Flannery , Alissa O'Halloran , Charisse N. Cummings , Shikha Garg , Peng-Jun Lu , Tammy A. Santibanez , Carrie Reed , Matthew Biggerstaff , A. Danielle Iuliano
{"title":"Estimating historical disease burden and the impact of vaccination by influenza type and subtype in the United States, 2016–2020","authors":"Sinead E. Morris , Sarabeth M. Mathis , Jessie R. Chung , Brendan Flannery , Alissa O'Halloran , Charisse N. Cummings , Shikha Garg , Peng-Jun Lu , Tammy A. Santibanez , Carrie Reed , Matthew Biggerstaff , A. Danielle Iuliano","doi":"10.1016/j.jvacx.2025.100700","DOIUrl":"10.1016/j.jvacx.2025.100700","url":null,"abstract":"<div><div>Seasonal influenza causes substantial morbidity and mortality in the United States. The U.S. Centers for Disease Control and Prevention (CDC) uses a compartmental framework to estimate the annual disease burden and burden prevented by vaccination for all influenza types and subtypes combined. However, these estimates do not capture underlying shifts in disease burden caused by different circulating influenza virus types or subtypes. We demonstrate an extension of the current framework to estimate disease burden and burden prevented by vaccination for influenza A virus subtypes A(H1N1) and A(H3N2), and influenza type B viruses. We applied this method to data from the 2016/17 to 2019/20 seasons that included age- and virus-specific hospitalizations and vaccine effectiveness estimates, and age-specific vaccination coverage estimates. We estimated the number of symptomatic illnesses, medically-attended illnesses, hospitalizations, and deaths caused by each virus, and the corresponding number prevented by vaccination. Disease burden and vaccine-prevented disease burden varied substantially by season, age, and virus type or subtype. The greatest disease burden was estimated in 2017/18, whereas 2019/20 had the greatest burden prevented by vaccination. Influenza A viruses contributed most to disease burden in all seasons. Vaccination against influenza B viruses prevented the largest percentage of hospitalizations among children and adults <65 years, whereas vaccination against A(H1N1) prevented the largest percentage of hospitalizations among adults ≥65 years. Overall, our results highlight complex variability in influenza disease burden by season, age, and virus type and subtype. These findings can be used to improve our understanding of the factors impacting influenza disease burden each season and to enhance communications of the value of influenza vaccination.</div></div>","PeriodicalId":43021,"journal":{"name":"Vaccine: X","volume":"26 ","pages":"Article 100700"},"PeriodicalIF":2.2,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144829839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Reasons for unvaccinated booster dose of COVID-19, adverse reaction after vaccination, and COVID-19 infection status among those with COVID-19 booster vaccination hesitancy","authors":"Sho Takahashi , Shohei Sakai , Yuichiro Ohki , Kaede Tobe , Yurie Kobashi , Masaharu Tsubokura","doi":"10.1016/j.jvacx.2025.100701","DOIUrl":"10.1016/j.jvacx.2025.100701","url":null,"abstract":"<div><h3>Background</h3><div>We have previously reported reasons for vaccine hesitance among those who did not receive the coronavirus disease 2019 (COVID-19) vaccination. However, the detailed causes of hesitancy related to booster vaccinations remain largely uninvestigated. This study aimed to describe why individuals who received one or two vaccine doses avoided booster shots.</div></div><div><h3>Methods</h3><div>In March 2023, a cross-sectional Internet survey was conducted to investigate the reasons for vaccine hesitancy and the extent of adverse reactions following vaccination among individuals who had not received a booster dose in Japan. Survey items included social demographics, comorbidities, history of SARS-CoV-2 infection, history of COVID-19 vaccination, adverse reactions to COVID-19 vaccines, and reasons for vaccination decline. The reasons for avoiding vaccination were summarized.</div></div><div><h3>Results</h3><div>In this study, 545 individuals were included: 262 did not receive vaccination, 21 received one dose, and 263 received two doses by March 2023. The most common reason for avoiding subsequent booster doses among individuals who received one or two doses of the vaccine was concerns about adverse reactions (n[%] = 192 [67.8 %]), followed by concerns about vaccine safety (n[%] = 154 [54.4 %]). The proportion of vaccine safety concerns was lower in the booster vaccination hesitant group than in the non-vaccination group (<em>p</em> < 0.001). The group that avoided booster vaccination due to adverse reactions experienced all types of adverse reactions more severely than those for which adverse reactions were not a reason for vaccine hesitancy.</div></div><div><h3>Conclusions</h3><div>The most prominent reason for avoiding booster doses after receiving one or two doses of the COVID-19 vaccine was related to concerns regarding associated side effects. To prevent vaccine hesitancy regarding booster doses, including COVID-19, the strategy for reducing discomfort caused by these adverse reactions should involve the first and second doses.</div></div>","PeriodicalId":43021,"journal":{"name":"Vaccine: X","volume":"26 ","pages":"Article 100701"},"PeriodicalIF":2.2,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144841615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}