Influenza Virus Vaccines Commons^™

Interim Estimates Of 2025-26 Seasonal Influenza Vaccine Effectiveness - United States, September 2025-February 2026., Patrick Maloney, Emily L. Reeves, Kristina Wielgosz, Ashley M. Price, Karthik Natarajan, Malini B. Desilva, Kristin Dascomb, Nicola P. Klein, Sara Y. Tartof, Stephanie A. Irving, Shaun J. Grannis, Toan C. Ong, Zachary A. Weber, Jennifer E. Schuster, Danielle M. Zerr, Marian G. Michaels, Julie A. Boom, Natasha B. Halasa, Mary A. Staat, Geoffrey A. Weinberg, Stacey L. House, Elie A. Saade, Krissy Moehling Geffel, Manjusha Gaglani, Karen J. Wernli, Vel Murugan, Emily T. Martin, Natalie A B Bontrager, Marie K. Kirby, Amanda B. Payne, Fatimah S. Dawood, Ayzsa Tannis, Heidi L. Moline, Sifang Kathy Zhao, Katherine Adams, Jennifer Decuir, Samantha M. Olson, Jessie R. Chung, Nathaniel Lewis, Brendan Flannery, Carrie Reed, Shikha Garg, Sascha Ellington, Cdc Influenza Vaccine Effectiveness Collaborators

Manuscripts, Articles, Book Chapters and Other Papers

In the United States, annual influenza vaccination has been recommended for all persons aged ≥6 months, including during the 2025-26 season. Interim influenza vaccine effectiveness (VE) estimates were calculated for patients with acute respiratory illness-associated outpatient visits and hospitalizations from three U.S. respiratory virus VE networks during the 2025-26 influenza season, using a test-negative case-control design. Among children and adolescents aged < 18 years, VE was 38%-41% against influenza outpatient visits and 41% against influenza-associated hospitalization. Among adults aged ≥18 years, VE was 22%-34% against influenza outpatient visits and 30% against influenza-associated hospitalization. Among children and adolescents, VE against influenza A ranged from 37% (against outpatient visits) to 42% (against hospitalization) across settings; among adults, VE against influenza A ranged from 30% (against hospitalization) to 34% (against outpatient visits) across settings. Among children and adolescents, VE against influenza A(H3N2)-associated outpatient visits was 35% and against influenza A(H3N2)-associated hospitalization was 38%. VE against influenza B outpatient visits ranged from 45%-71% among children and adolescents and was 63% among adults. Other estimates of VE were not statistically significant or were not reportable. Although interim influenza VE is lower during the 2025-26 influenza season than it was during recent influenza seasons, these findings demonstrate that influenza vaccination still provides protection against influenza. CDC recommends influenza vaccination; U.S. influenza vaccines remain available for persons aged ≥6 months.

Interim Estimates Of 2024-2025 Seasonal Influenza Vaccine Effectiveness - Four Vaccine Effectiveness Networks, United States, October 2024-February 2025., Aaron M. Frutos, Seana Cleary, Emily L. Reeves, Haris M. Ahmad, Ashley M. Price, Wesley H. Self, Yuwei Zhu, Basmah Safdar, Ithan D. Peltan, Kevin W. Gibbs, Matthew C. Exline, Adam S. Lauring, Sarah W. Ball, Malini Desilva, Sara Y. Tartof, Kristin Dascomb, Stephanie A. Irving, Nicola P. Klein, Brian E. Dixon, Toan C. Ong, Ivana A. Vaughn, Stacey L. House, Kiran A. Faryar, Mary Patricia Nowalk, Manjusha Gaglani, Karen J. Wernli, Vel Murugan, Olivia L. Williams, Rangaraj Selvarangan, Geoffrey A. Weinberg, Mary A. Staat, Natasha B. Halasa, Leila C. Sahni, Marian G. Michaels, Janet A. Englund, Marie K. Kirby, Diya Surie, Fatimah S. Dawood, Benjamin R. Clopper, Heidi L Moline, Ruth Link-Gelles, Amanda B. Payne, Elizabeth Harker, Kristina Wielgosz, Zachary A. Weber, Duck-Hye Yang, Nathaniel M. Lewis, Jennifer Decuir, Samantha M. Olson, Jessie R. Chung, Brendan Flannery, Lisa A. Grohskopf, Carrie Reed, Shikha Garg, Sascha Ellington, Cdc Influenza Vaccine Effectiveness Collaborators

Manuscripts, Articles, Book Chapters and Other Papers

Annual influenza vaccination is recommended for all persons aged ≥6 months in the United States. Interim influenza vaccine effectiveness (VE) was calculated among patients with acute respiratory illness-associated outpatient visits and hospitalizations from four VE networks during the 2024-25 influenza season (October 2024-February 2025). Among children and adolescents agedyears, VE against any influenza was 32%, 59%, and 60% in the outpatient setting in three networks, and against influenza-associated hospitalization was 63% and 78% in two networks. Among adults aged ≥18 years, VE in the outpatient setting was 36% and 54% in two networks and was 41% and 55% against hospitalization …

Immunogenicity And Reactogenicity Of High- Or Standard-Dose Influenza Vaccine In A Second Consecutive Influenza Season., Hannah Bahakel, Andrew J. Spieker, Haya Hayek, Jennifer E. Schuster, Lubna Hamdan, Daniel E. Dulek, Carrie L. Kitko, Tess Stopczynski, Einas Batarseh, Zaid Haddadin, Laura S. Stewart, Anna Stahl, Molly Potter, Herdi Rahman, Justin Amarin, Spyros A. Kalams, Claire E. Bocchini, Elizabeth A. Moulton, Susan E. Coffin, Monica I. Ardura, Rachel L. Wattier, Gabriela Maron, Michael Grimley, Grant Paulsen, Christopher J. Harrison, Jason Freedman, Paul A. Carpenter, Janet A. Englund, Flor M. Munoz, Lara Danziger-Isakov, Natasha Halasa, Pediatric Hct Flu Study

Manuscripts, Articles, Book Chapters and Other Papers

BACKGROUND: Pediatric hematopoietic cell transplant (HCT) recipients are at high risk for morbidity from influenza virus infection. We demonstrated in a primary phase 2 randomized controlled trial that 2 post-HCT doses of high-dose trivalent influenza vaccine (HD-TIV) given 4 weeks apart were more immunogenic than 2 doses of standard-dose quadrivalent influenza vaccine (SD-QIV). Herein, we present the immunogenicity and safety of influenza vaccination in a consecutive season post-HCT using the same dosing regimen.

METHODS: A subcohort of study participants reenrolled and had hemagglutinin inhibition titers measured at baseline and 4 weeks after each vaccine dose in year 2. We estimated …

Estimated Vaccine Effectiveness For Pediatric Patients With Severe Influenza, 2015-2020., Kelsey M. Sumner, Leila C. Sahni, Julie A. Boom, Natasha B. Halasa, Laura S. Stewart, Janet A. Englund, Eileen J. Klein, Mary A. Staat, Elizabeth P. Schlaudecker, Rangaraj Selvarangan, Christopher J. Harrison, Geoffrey A. Weinberg, Peter G. Szilagyi, Monica N. Singer, Parvin H. Azimi, Benjamin R. Clopper, Heidi L. Moline, Emma K. Noble, John V. Williams, Marian G. Michaels, Samantha M. Olson, New Vaccine Surveillance Network Collaborators

Manuscripts, Articles, Book Chapters and Other Papers

IMPORTANCE: Increasing the understanding of vaccine effectiveness (VE) against levels of severe influenza in children could help increase uptake of influenza vaccination and strengthen vaccine policies globally.

OBJECTIVE: To investigate VE in children by severity of influenza illness.

DESIGN, SETTING, AND PARTICIPANTS: This case-control study with a test-negative design used data from 8 participating medical centers located in geographically different US states in the New Vaccine Surveillance Network from November 6, 2015, through April 8, 2020. Participants included children 6 months through 17 years of age who were hospitalized or presented to an emergency department (ED) with acute respiratory illness. …

A Longitudinal Seroepidemiology Study To Evaluate Antibody Response To Sars-Cov-2 Virus Infection And Vaccination In Children In Calgary, Canada From July 2020 To April 2022: Alberta Covid-19 Childhood Cohort (Ab3c) Study, Emily J Doucette, Joslyn Gray, Kevin Fonseca, Carmen Charlton, Jamil N Kanji, Graham Tipples, Susan Kuhn, Jessica Dunn, Payton Sayers, Nicola Symonds, Guosong Wu, Stephen B Freedman, James D Kellner

Faculty, Staff and Student Publications

BACKGROUND: Measurement of SARS-CoV-2 antibody seropositivity is important to accurately understand exposure to infection and/or vaccination in specific populations. This study aimed to estimate the serologic response to SARS-CoV-2 virus infection and vaccination in children in Calgary, Alberta over a two-year period.

METHODS: Children with or without prior SARS-CoV-2 infections, were enrolled in Calgary, Canada in 2020. Venous blood was sampled 4 times from July 2020 to April 2022 for SARS-CoV-2 nucleocapsid and spike antibodies. Demographic and clinical information was obtained including SARS-CoV-2 testing results and vaccination records.

RESULTS: 1035 children were enrolled and 88.9% completed all 4 visits; median …

Evaluation Of Mrna-1273 Vaccine In Children 6 Months To 5 Years Of Age, Evan J Anderson, C Buddy Creech, Vladimir Berthaud, Arin Piramzadian, Kimball A Johnson, Marcus Zervos, Fredric Garner, Carl Griffin, Khozema Palanpurwala, Mark Turner, Jeffrey Gerber, Richard L Bennett, Kashif Ali, Madhavi Ampajwala, Gary Berman, Jennifer Nayak, Carey Chronis, Barbara Rizzardi, William J Muller, Christopher A Smith, George Fuchs, Daniel Hsia, Joanne E Tomassini, Dianne Delucia, Caroline Reuter, Barbara Kuter, Xiaoping Zhao, Weiping Deng, Honghong Zhou, Daniela Ramirez Schrempp, Kelly Hautzinger, Bethany Girard, Karen Slobod, Roderick Mcphee, Rolando Pajon, Anne Aunins, Rituparna Das, Jacqueline M Miller, Sabine Schnyder Ghamloush, Kidcove Study Group

Faculty, Staff and Student Publications

BACKGROUND: The safety, reactogenicity, immunogenicity, and efficacy of the mRNA-1273 coronavirus disease 2019 (Covid-19) vaccine in young children are unknown.

METHODS: Part 1 of this ongoing phase 2-3 trial was open label for dose selection; part 2 was an observer-blinded, placebo-controlled evaluation of the selected dose. In part 2, we randomly assigned young children (6 months to 5 years of age) in a 3:1 ratio to receive two 25-μg injections of mRNA-1273 or placebo, administered 28 days apart. The primary objectives were to evaluate the safety and reactogenicity of the vaccine and to determine whether the immune response in these …

Efficacy Of Typhoid Conjugate Vaccine In Nepal: Final Results Of A Phase 3, Randomised, Controlled Trial, Mila Shakya, Merryn Voysey, Katherine Theiss-Nyland, Rachel Colin-Jones, Dikshya Pant, Anup Adhikari, Susan Tonks, Yama F Mujadidi, Peter O'Reilly, Olga Mazur, Sarah Kelly, Xinxue Liu, Archana Maharjan, Ashata Dahal, Naheeda Haque, Anisha Pradhan, Suchita Shrestha, Manij Joshi, Nicola Smith, Jennifer Hill, Jenny Clarke, Lisa Stockdale, Elizabeth Jones, Timothy Lubinda, Binod Bajracharya, Sabina Dongol, Abhilasha Karkey, Stephen Baker, Gordan Dougan, Virginia E Pitzer, Kathleen M Neuzil, Shrijana Shrestha, Buddha Basnyat, Andrew J Pollard

Faculty, Staff and Student Publications

BACKGROUND: Typhoid fever is a major public health problem in low-resource settings. Vaccination can help curb the disease and might reduce transmission. We have previously reported an interim analysis of the efficacy of typhoid conjugate vaccine (TCV) in Nepali children. Here we report the final results after 2 years of follow-up.

METHODS: We did a participant-masked and observer-masked individually randomised trial in Lalitpur, Nepal, in which 20 019 children aged 9 months to younger than 16 years were randomly assigned in a 1:1 ratio to receive a single dose of TCV (Typbar TCV, Bharat Biotech International, India) or capsular group …

Cost Effectiveness Analysis Of Year 2 Of An Elementary School-Located Influenza Vaccination Program-Results From A Randomized Controlled Trial., Byung-Kwang Yoo, Sharon Humiston, Peter G. Szilagyi, Stanley J. Schaffer, Christine Long, Maureen Kolasa

Manuscripts, Articles, Book Chapters and Other Papers

BACKGROUND: School-located vaccination against influenza (SLV-I) has the potential to improve current suboptimal influenza immunization coverage for U.S. school-aged children. However, little is known about SLV-I's cost-effectiveness. The objective of this study is to establish the cost-effectiveness of SLV-I based on a two-year community-based randomized controlled trial (Year 1: 2009-2010 vaccination season, an unusual H1N1 pandemic influenza season, and Year 2: 2010-2011, a more typical influenza season).

METHODS: We performed a cost-effectiveness analysis on a two-year randomized controlled trial of a Western New York SLV-I program. SLV-I clinics were offered in 21 intervention elementary schools (Year 1 n = 9,027; …