Research Focus: World Immunisation Week 2026

April 2026: World Immunisation Week 2026 - Special edition of our monthly Research Focus series. #WIW26

WIW2026

A narrative review of heterogeneity in SARS-CoV-2 infection outcomes and vaccine efficacy: strategizing pandemic preparedness in Africa

Researchers from TIBA, Usher Institute and Institute of Immunology and Infection Research review why Africa saw fewer COVID-19 hospitalizations and deaths than early predictions, evaluating hypotheses spanning underreporting, demographics, climate, mitigation, lifestyle, pre-existing cross-reactive immunity, and host genetics, and identifying key evidence gaps. 
 
They assess how vaccine responses may vary within Africa and globally due to factors such as pre-existing immunity, nutrition, co-infections, comorbidities, microbiome composition, genetic polymorphisms, and demographics—emphasizing that prior immunity can both enhance protection and impede new vaccines via original antigenic sin and immune imprinting. 
 
They call for targeted immunology studies to quantify the role of cross-reactive immunity in disease epidemiology, strengthen preparedness and vulnerability assessments, and inform vaccine design and effectiveness monitoring, using SARS-CoV-2 as a case study aligned with the 100-day mission for future pandemics.
 
Citation: Kerai T, Woolhouse M, Nyazema NZ, Mutapi F. Front Public Health. 2026 Feb 3;14:1761547. doi: 10.3389/fpubh.2026.1761547. PMID: 41710320; PMCID: PMC12909571.

Maternal perspectives on the RSV vaccine (Abrysvo): a thematic analysis of survey findings from the first season of implementation in England and Scotland

Researchers from Child Life and Health and the Centre for Inflammation Research conducted a qualitative study of 388 vaccine-eligible mothers across 30 sites (Sept 2024–Mar 2025) on the newly introduced RSVpreF maternal vaccine (Abrysvo, Pfizer). 

Four consistent themes emerged: access-related barriers, insufficient RSV information for informed decisions, safety concerns and hesitancy, and recognition of the vaccine’s protective benefits. 

Researchers conclude that improving vaccine delivery, enhancing awareness, and providing personalised antenatal counselling—alongside addressing structural inaccessibility—are essential to increase uptake, and call for ongoing qualitative research to guide targeted public health strategies ahead of future RSV seasons.

Citation: O'Hagan S, Williams TC, Marlow R, Drysdale SB, Cunningham S, Groves HE, Mpamhanga CD, Lyttle MD, Hunt S, Liu X, Waterfield T, Roland D, Iskander D, Woolfall K; PERUKI & BronchStart Collaboration. Arch Dis Child. 2026 Feb 27:archdischild-2025-329427. doi: 10.1136/archdischild-2025-329427. Epub ahead of print. PMID: 41741000.


Systematic review and meta-analysis of COVID-19 mRNA vaccine effectiveness against hospitalizations in adults

Researchers from Edinburgh Medical School and the Roslin Institute conducted a systematic review and meta-analysis of real-world effectiveness of the Pfizer-BioNTech BNT162b2 and Moderna mRNA-1273 vaccines against coronavirus disease 2019 (COVID-19) hospitalisation, chosen as the primary outcome to reflect prevention of severe disease. 

A search of the Medline and Embase databases on 25 February 2024 identified 18,347 records; 50 studies met inclusion criteria. Pooled vaccine effectiveness (VE) for both the 2-dose primary series and 3-dose (booster) schedules was 84–86%, indicating strong protection.

Booster doses appeared to restore waning effectiveness, with no significant overall difference between 2-dose and 3-dose VE. Subgroup analyses linked circulation of the Omicron variant of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) to reduced VE, suggesting future variants could similarly affect performance. 

As a result, researchers called for adaptable vaccine strategies, ongoing surveillance, and better data on underrepresented populations.

Citation: Wong BK, Mabbott NA. Immunother Adv. 2024 Nov 27;4(1):ltae011. doi: 10.1093/immadv/ltae011. PMID: 39703784; PMCID: PMC11655844.


Evaluation of a strategy to enhance the efficacy and ease of application of porcine reproductive and respiratory syndrome virus vaccines

Control of porcine reproductive and respiratory syndrome virus (PRRSV) is limited by uneven vaccine performance and on-farm handling issues.

In a study of 45 PRRSV‑naïve piglets, researchers from Moredun Research Institute and Roslin Institute compared a needle‑free solid‑dose modified live virus (MLV) PRRSV‑1 prime, with or without a nasal boost of inactivated vaccine, against the standard intramuscular liquid MLV. 

After challenge with a PRRSV‑1 field strain, they measured virus levels in blood and nose and antibody responses. 

The nasal boost did not add benefit, but the solid‑dose MLV alone induced neutralising antibodies and reduced viremia, shedding, and lung lesions as effectively as the standard injection. These results support solid‑dose formulations as a practical alternative for PRRSV vaccination in pigs.

Citation: Schiavone A, Edwards JC, Vigneswaran E, De Brito RCF, Hothi H, Frossard JP, Beechener ES, Calvert JG, Burkard CT, Balasch M, Seaton AV, Stevens M, Howard MK, Graham SP, Opriessnig T. Vaccine. 2025 Oct 3;64:127757. doi: 10.1016/j.vaccine.2025.127757. Epub 2025 Sep 19. PMID: 40974733.


Real-world evidence on RSV vaccine uptake, effectiveness, and safety in older adults: a systematic review and meta-analysis

Researchers from the Usher Institute and Institute for Neuroscience and Cardiovascular Research conducted a systematic review and meta-analysis of post-licensure, real-world studies on respiratory syncytial virus (RSV) vaccines in older adults. 

Across 36 studies covering over 121.8 million people in nine countries, vaccine uptake in the United States among adults aged 60 years and older during the 2023/24 season was 18%, with clear disparities by clinical and sociodemographic factors. 

Pooled vaccine effectiveness was high: about 75% against laboratory-confirmed RSV infection, 76% against emergency department (ED) or urgent care visits, 75% against RSV-related hospital admissions, and 80% against severe RSV disease.

Overall, uptake was low but the vaccines showed strong effectiveness and a generally favorable safety profile, supporting wider implementation and efforts to reduce access and equity gaps.

Citation: Trusinska D, Lee B, Ferdous S, Lansbury L, Burden C, Anand A, Stowe J, Mensah A, Lim W, Marsh K, Gibbons C, Shi T. Lancet Reg Health Eur. 2026 Feb 20;64:101623. doi: 10.1016/j.lanepe.2026.101623. PMID: 41767892; PMCID: PMC12936786.


Decline in UK childhood vaccine uptake

Researchers from the School of Social and Political Science report that in 2023–24 no childhood vaccine in England met the WHO 95% target; first-dose MMR coverage at age 2 fell to 88.9% (from 92.7% in 2013–14), fueling measles outbreaks in deprived areas (2,911 cases in 2024; one child death in 2025). 

Declines reflect COVID-19 disruption plus deeper system faults: post-2012 service fragmentation, split accountability across the NHS, UKHSA and local authorities, short-term funding, and austerity-era cuts (over 30% of Sure Start centres closed; >40% fewer health visitors). The new Best Start family services could help via health visiting, but 50% cost cuts for integrated care boards risk undermining recovery. 

Priorities are opportunistic “every contact counts” offers, co-designed communications, strong Yellow Card safety reporting and annual vaccinator training, backed by sustained, coordinated investment with clear accountability.

Citation: Kasstan-Dabush B, Chantler T, Bedford H. BMJ. 2025 Jul 21;390:r1500. doi: 10.1136/bmj.r1500. PMID: 40691007; PMCID: PMC12305403.


Human papillomavirus vaccination uptake among men who have sex with men living with HIV

Researchers from Usher Institute conducted a systematic review (2010–2022) of quantitative studies reporting human papillomavirus (HPV) vaccine uptake among men who have sex with men (MSM) and MSM living with human immunodeficiency virus (HIV) (MSMLWH). Nineteen studies from high-income countries showed wide uptake: 2.7%–91.5% in HIV-negative MSM and 5.6%–90% in MSMLWH. 

Despite heterogeneity, uptake has increased over time—especially among younger men—and is generally higher in MSMLWH, but remains suboptimal overall. The authors call for research and policy to remove barriers to HPV vaccination in these groups.

Citation: Moran C, Garcia-Iglesias J, Kerr C. Sex Transm Infect. 2025 Aug 28;101(6):414-421. doi: 10.1136/sextrans-2024-056361. PMID: 40015961.


T cell memory response to MPXV infection exhibits greater effector function and migratory potential compared to MVA-BN vaccination

Researchers from the Pandemic Science Hub and Roslin Institute studied memory T-cell responses to mpox (monkeypox) in people who had recovered from infection and in people vaccinated with MVA-BN (Modified Vaccinia Ankara–Bavarian Nordic). They found strong CD8+ and CD4+ T-cell responses, mainly targeting early viral proteins, and mapped seven key immune targets (epitopes), focusing in detail on one dominant target. 

Overall, infection-induced T cells showed greater ability to kill infected cells, move to sites of infection, and expand in number than vaccine-induced T cells, despite similar activation profiles. These findings suggest mpox infection can leave more potent memory T cells, with implications for long-term protection and future vaccine design.

Citation: Chen JL, Wang B, Lu Y, Antoun E, Bird O, Drennan PG, Yin Z, Liu G, Yao X, Pidoux M, Bates A, Jayathilaka D, Wang J, Angus B, Beer S, Espinosa A, Baillie JK, Semple MG; ISARIC4C Investigators; Rostron T, Waugh C, Sopp P, Knight JC, Fullerton JN, Coles M, Smith GL, Mentzer AJ, Peng Y, Dong T. Nat Commun. 2025 May 10;16(1):4362. doi: 10.1038/s41467-025-59370-5. PMID: 40348752; PMCID: PMC12065855.


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