Corporate report

Number of animals used: 2025

Updated 9 July 2026

Our primary duty is to protect the public’s health from infectious disease and other health hazards. The vast majority of our scientific research does not involve animals but the biological similarities between humans and other species mean that they can, on some occasions, be the only effective model for research into infectious diseases and other health impacts where the response to infection, vaccination or environmental hazards is too complex to be modelled in any other way. Animals are only used where there is no viable alternative.

Together with over 130 organisations and universities, we have signed up to the Concordat on Openness in Animal Research in recognition of the important work we undertake that involves animals. At the UK Health Security Agency (UKHSA) we are committed to the refinement, reduction and replacement of animals in research, and continually develop and implement new enrichment methods, make refinements to procedures to reduce harms, look to reduce animal numbers, and develop and use alternative cell and microfluidic models wherever possible.

The tables provide the numbers of procedures carried out, per species, at our scientific campuses at Porton (including PBL), Colindale and Chilton, in 2025.

Porton

Table 1. Annual return figures 2025: UKHSA Porton

	NHP	Mice	Guinea Pigs	Hamsters	Ferrets	Rabbits
Non Recovery	10	0	0	0	0	0
Mild	62	189	0	32	149	0
Mod	35	93	0	64	4	0
Severe	0	124	2	8	20	0
Total	97	406	2	104	173	0

Coronaviruses

Non-lethal models for MERS-CoV were developed using hamsters and non-human primates to support the development and evaluation of broadly protective beta-coronavirus vaccines, including MERS-CoV model development activities.

Further work included the development of a flexible platform model using adenoviral transduction with MERS-CoV infection, designed to enable rapid modelling of emerging pathogens (‘Disease X’) and to accelerate countermeasure testing in a controlled, translational framework.

Influenza

The ongoing risk of emergence of re-assorted influenza viruses from animal reservoirs continued to present a pandemic threat. In particular, highly pathogenic avian influenza (HPAI) viruses remained of significant concern due to their increasing host range, potential for adaptation to sustained human-to-human transmission, and typically more severe clinical presentation compared with seasonal influenza strains.

To address this, UKHSA undertook development of the HPAI ferret model, enabling:

1. Assessment of candidate vaccines and therapeutics targeting HPAI viruses
2. Testing of HPAI vaccine candidates
3. Evaluation of seasonal influenza vaccine cross-protection against HPAI strains

Assessment of neuraminidase-targeted immunity was also undertaken in the ferret influenza model, enabling evaluation of the contribution of anti-neuraminidase responses to protection against infection and disease. This work supported improved understanding of non-haemagglutinin correlates of protection and informed the development of next-generation or broader influenza vaccines.

In addition, non-human primate (NHP) studies were conducted to assess the immunogenicity of HPAI vaccine candidates, providing critical translational data on the magnitude, breadth, and durability of immune responses. These studies supported evaluation of both humoral and cellular immunity and played an important role in bridging small animal findings to human clinical development.

UKHSA continued its role as an Outside Testing Laboratory for AstraZeneca, conducting vaccine release testing. The established ferret non-lethal influenza model was used for GMP safety testing of the live attenuated influenza vaccine (LAIV). Beyond release testing, the model was further optimised and applied to:

1. Assess influenza vaccine effectiveness, particularly LAIV
2. Improve clinical translatability of preclinical findings
3. Support broader evaluation of vaccine performance against evolving influenza strains

Tuberculosis

Guinea pig studies

Drug‑resistant forms of tuberculosis remain one of the most significant drivers of global antimicrobial resistance, and the threat they pose continues to grow each year. Around half a million people develop drug‑resistant TB annually. When individuals are infected with strains that no longer respond to isoniazid and rifampicin—the 2 cornerstone first‑line medicines—they are classified as having multidrug‑resistant (MDR) TB, a condition that standard treatments can no longer reliably cure.

Researchers across the TB field are working together to prevent a future in which TB once again becomes effectively untreatable. As part of this global effort, UKHSA collaborates with developers of new TB drugs and vaccines to assess how well innovative compounds and vaccine candidates perform in carefully optimised in vivo models. This work helps ensure that only the safest and most promising candidates advance into human clinical trials, strengthening the pipeline of future TB interventions.

Macaque studies

Work has been performed in macaques to support the global effort to combat tuberculosis. Studies have been conducted to assess the efficacy of new drug regimens to treat tuberculosis and to establish refined models for the evaluation of vaccine efficacy against clinical strains of Mycobacterium tuberculosis. Refined sampling techniques together with the associated tools required to characterise immune responses at key mucosal sites have been established and are providing new insights into the impact of vaccination at mucosal sites.

Virology and pathogenesis

2025 continued on a successful trajectory from previous years to continue development and understanding of in vivo disease models that are invaluable for therapy efficacy studies and reducing disease burden in low- and middle-income countries (LMICs). Specifically, an in vivo model of disease was successfully developed for Rift Valley Fever virus (RVFV) in a non-human primate (NHP) model, that can be used in clinical intervention trials as vaccine candidates progress towards licensure. Other studies compared the susceptibility of mice and hamsters to Oropouche virus (OROV), with mice producing the most consistent clinical readouts. Immunogenicity studies assessed vaccine candidates for several pathogens of concern (Lassa, Zika and Crimean-Congo haemorrhagic fever virus) and CCHFV therapies were assessed in a challenge model.

2025 publications include:

1. Swan K and others. ‘Histopathological and immunohistochemical characterization of lesions in the golden Syrian hamster model of Nipah virus infection (Bangladesh strain)’ Frontiers in Veterinary Science 2026: volume 12, pages 1708412 doi: 10.3389/fvets.2025.1708412 PMID: 41635792 PMCID: PMC12862940

2. Crossley L and others. ‘Susceptibility and transmission of mpox virus infection in brown rats (Rattus norvegicus)’ Journal of General Virology 2025: volume 106, issue 7, pages 002125 doi: 10.1099/jgv.0.002125 Erratum in: Journal of General Virology 2025: volume 106, issue 10 doi: 10.1099/jgv.0.002162 PMID: 40590853 PMCID: PMC12214244

3. Pfranger M and others. ‘Immunogenicity of a trivalent haemorrhagic fever vaccine candidate against Sudan virus, Marburg virus and Lassa virus in an mpox vaccine’ Journal of General Virology 2025: volume 106, issue 10, pages 002157 doi: 10.1099/jgv.0.002157 PMID: 41051941 PMCID: PMC12500382

4. Easterbrook L and others. ‘Genomic changes of Lassa virus associated with mammalian host adaptation’ BMC Genomics 2025: volume 26, issue 1, pages 489 doi: 10.1186/s12864-025-11666-y PMID: 40375146 PMCID: PMC12079963

Bacterial infections

Yersinia Plague, caused by the bacterium Yersinia pestis, is estimated to have been responsible for at least 200 million deaths throughout recorded human history. Pneumonic plague poses a particular concern to human health, as successful treatment depends on the rapid administration of antibiotic treatment. Mouse models provide an important tool for studying disease progression and evaluating the effectiveness of vaccines and other medical countermeasures against aerosol exposure to Yersinia pestis. At UKHSA, we work closely with vaccine developers and the wider scientific community to assess promising new vaccine candidates using well-characterised in vivo models. These studies help identify the safest and most effective interventions for progression towards clinical development.

Pseudomonas aeruginosa is a highly adaptable opportunistic bacterial pathogen. Although it rarely causes illness in healthy individuals, it can lead to a wide range of serious infections in those with weakened immune systems, particularly in healthcare settings. Those at highest risk include cancer patients, newborns, and individuals with severe burns, diabetes mellitus or cystic fibrosis. Pseudomonas aeruginosa exhibits intrinsic resistance to many antibiotics and has a notable capacity to acquire new resistance, making treatment increasingly difficult. UKHSA has established mouse models that replicate chronic infection to support the evaluation of new drugs, vaccines and other therapeutic approaches in collaboration with academic and industrial partners.

Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii. Human infection most commonly occurs through inhalation of contaminated aerosols originating from infected livestock, including sheep, goats and cattle. Although many infections are mild or asymptomatic, Q fever can cause severe illness, including pneumonia, hepatitis and, in some cases, long-term complications such as chronic endocarditis. Animal models are essential for understanding how the disease develops and for assessing the effectiveness of vaccines, therapeutics and diagnostic approaches. At UKHSA, mouse in vivo models have been established and are used in collaboration with academic and industrial partners to support the development and evaluation of novel medical countermeasures against Q fever. This work contributes to improving preparedness and ensuring that the safest, most promising interventions can progress towards future clinical development.

Assay development and replacement technologies

In 2025,12 macaques were used under non-recovery procedures to provide tissues and blood for the development of organ-on-a-chip culture methods that will replace and reduce animal use, and for critical naive controls for a variety of immunological assays for vaccine and/or therapeutic studies.

Porton Biopharma Ltd

Table 2. Annual return figures 2025: Porton Biopharma Limited (PBL)

	NHP	Mice	Guinea Pigs	Hamsters	Ferrets	Rabbits
Non Recovery	0	0	0	0	0	0
Mild	0	0	0	0	0	2
Mod	0	0	96	0	0	0
Severe	0	0	218	0	0	0
Total	0	0	314	0	0	2

PBL’s work is focussed on quality-assured development of life-saving biopharmaceuticals. We manufactured the licensed product Erwinase, a childhood leukaemia therapy, and the UK’s licensed anthrax vaccine. As part of the licence, there is a requirement to undertake a limited number of animal tests to ensure that each batch of the vaccine is safe and effective. This involves guinea pigs and rabbits. We continue to meet our commitment to the licence ensuring each batch of our vaccine is safe and effective.

Chilton

Table 3. Annual return figures 2025: UKHSA Chilton

	NHP	Mice	Guinea Pigs	Hamsters	Ferrets	Turkeys
Non Recovery	0	0	0	0	0	0
Mild	0	24	0	0	0	0
Mod	0	0	0	0	0	0
Severe	0	0	0	0	0	0
Total	0	24	0	0	0	0

Project title: Exploring lipid dynamics in animal organs affected by inhaled particulate matter through quasi-elastic neutron scattering (QENS)

Inhaled diesel exhaust particles (DEP) pose a threat to human health as these particles can penetrate deep into the lungs and trigger systemic effects that can then affect key organs such as the lung and brain. However, the effects of particulate matter exposure on membrane dynamics, particularly lipid behaviour, remain relatively unexplored. This study aims to use the facilities at the ISIS Neutron and Muon Source to investigate the impact of particulate exposure on lipid dynamics, which could provide valuable mechanistic insights into the biological effects of air pollutants.

Objectives: The experiments proposed involve using the OSIRIS instrument at ISIS to conduct quasi-elastic neutron scattering (QENS) experiments. These experiments aim to investigate the dynamics of lipids affected by particles within a complex and advanced biological system. To move beyond cellular models, the proposed experiment will assess lipid dynamics in key organs (for example, lung and brain) derived from animal experiments. This will involve comparing conditions with and without inhaled particles, as well as comparing between healthy and compromised conditions under inflammatory status.

Animal experiences: Following intraperitoneal injection of lipopolysaccharide (LPS) or intranasal instillation of either diesel exhaust particles (DEPs) or control (water), the mice demonstrated some mild disorientation after isoflurane general anaesthesia with all animals back to normal orientation after approximately 1 to 3 minutes. Administration of DEPs and/or LPS did not result in any acute adverse effects, and no abnormal clinical signs were observed in any animals throughout the experimental period.

Colindale

Table 4. Annual return figures 2025: UKHSA Colindale

	NHP	Mice	Guinea Pigs	Hamsters	Ferrets	Turkeys
Non Recovery	0	0	58	0	0	0
Mild	0	18	0	0	7	122
Mod	0	0	0	0	0	0
Severe	0	0	0	0	0	0
Total	0	18	58	0	7	122

Guinea Pigs

In 2025, a total of 58 guinea pigs were use for assays related to the H3 subtype of influenza, we use guinea pig red blood cells (RBCs) in serological investigations, these red blood cells are used to evaluate the levels of immune response in humans.

Mice

A total of 18 mice were used to identify bacterial toxins (Clostridium botulinum). These tests are performed using clinical samples, iatrogenic, wound or food-related, from patients suspected of having contracted the bacteria.

Turkeys

For conducting influenza assays, 37 turkeys were used to provide normal red blood cells. Among the 37 birds, there were 122 phlebotomy procedures performed.

Ferrets

A total of 7 ferrets were used to produce antisera targeting novel and emerging strains of influenza, contributing to the advancement of flu vaccines as well as the monitoring, surveillance, and prediction of the influenza virus.