Lab-grown brain-spinal cord model shows

‘irreversible’ nerve damage may be

reversed

University of Cambridge

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A mini version of the connected human brain and spinal cord system created in the lab.

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Credit: Dr András Lakatos

Cambridge scientists have grown miniature circuits in the lab that mimic how the brain and spinal cord connect up, which underlies our movements. They used this model to show how damage to these connections previously considered ‘irreversible’ could, in fact, be reversible.

As we develop and grow from embryo to fetus to infant, our nerve cells (neurons) form connections, allowing information to be transmitted between the brain and the spinal cord. A key component of each neuron is the axon – the nerve fibre ‘cable’ that transmits information to other neurons to activate muscle contractions.

At some point, we lose the ability to grow axons in the central nervous system, or this ability is at least greatly impaired or slowed down. This means that damage to the brain and spinal cord becomes permanent, leading to devastating disabilities, such as the inability to grasp or walk. This is often the case for traumatic spinal cord injury and can be a feature of many neurological diseases, including motor neurone disease or multiple sclerosis.

In 2021, Dr András Lakatos and colleagues at the University of Cambridge developed ‘mini brains’ using human patient-derived stem cells – special cells that have the potential to develop into most human cell types – which they guided to grow into pea-sized brain ‘organoids’. These organoids were 3D models that resemble parts of the human cerebral cortex. The team used these to demonstrate molecular problems in motor neurone disease and potential ways to prevent them.

Now, in research published in Cell Reports, Dr Lakatos’s team has taken its research a step further, building a mini version of the connected human brain and spinal cord system in the lab by recreating these tissues using organoids.

In the human body, the brain and spinal cord tissues are distinct but connected by axons, so the researchers kept the brain and spinal cord organoids apart. They saw that nerve fibres from the brain tissue grew across the gap to connect to the spinal cord, forming a working circuit that could even cause tiny muscle clusters to contract.

By growing this human system in the dish for more than a year, they found that up until around day 150 – which corresponds to the mid-trimester of pregnancy – the axons were able to regrow after damage, but after this time, their growth was greatly impaired.

George Gibbons from the Department of Clinical Neurosciences at the University of Cambridge, the study’s first author, said: “Neurons taken from less mature organoids regrew long fibres after injury, but those from more mature organoids showed a sharp drop in their ability to regrow. In other words, poor regeneration is built into human neurons as they mature in the central nervous system.”

By analysing the gene expression – a sign of how active the genes are – in neurons that connect the brain and the spinal cord, they were able to identify a network of genes that acts as a ‘switch’ restricting the axon growth ability while the neurons mature to form connections (synapses). Amazingly, blocking key regulators of this network switched back on the ability of axons to grow.

The team then scanned a database of drug compounds to search for those that act on the genes in this network and identified as a candidate lynestrenol, a hormone drug licensed for managing certain menstrual disorders and as a contraceptive. When they tried this drug on damaged neurons, they found that it significantly boosted axon regrowth.

While scar tissue and inflammation may also restrict axon repair, exploring and tackling neuron-specific causes – the subject of this study – is very important. This is supported by evidence that axons of less mature neurons can grow through non-permissive environments that characterise injury sites.

Senior author Dr András Lakatos, who led the project at the Department of Clinical Neurosciences, said: “When the brain and spinal cord are damaged, the nerve fibres that carry movement signals from the brain to the spinal cord rarely grow back. That’s why paralysis is usually permanent. But we didn’t know exactly when the ability of axons to regenerate becomes limited. Our model provides a good indication that this block happens during development, and it can still be reversed after this point.

“Lynestrenol itself may not be the answer to spinal cord repair, but it shows us that, in principle, it should be possible to directly target human neurons and regenerate their axons. Although we still need to show that this strategy will also help to re-establish appropriate connections between the brain and spinal cord cells, this gives us hope that one day we may be able to treat conditions previously thought untreatable.”

Organoid models are an important way of understanding human biology. While animal models – for example, mice and rats – are useful for studying our biology as they share some similarities with humans, their differences ultimately limit what we can learn. Organoids grown from human stem cells can more closely mimic human biology.  

Dr Lakatos added: “Much of what we know about nerve regeneration comes from rodents, whose neurons behave differently from human neurons. Our sophisticated organoid models help bridge the knowledge gap from animal models to what we see in patients. They are also an important contribution to efforts to reduce the use of animals in research.”

Organoids, often referred to as ‘mini organs’, are being used increasingly to model human biology and disease. At the University of Cambridge alone, researchers use them to repair damaged livers, understand Crohn’s disease in children, and model the early stages of pregnancy, among many other applications.

The research was funded by the UK Research and Innovation Medical Research Council and Spinal Research.

Illustration of the mini version of the connected human brain and spinal cord system created in the lab.

Credit

Dr András Lakatos

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Journal

Cell Reports

DOI

10.1016/j.celrep.2026.117399 

Article Title

A human corticospinal organoid-slice connectoid model informs enhancer strategies for post-injury axon regrowth

Article Publication Date

26-May-2026

 

JMIR Report: Lab-grown brain organoids power biocomputers

Revisiting biological intelligence: JMIR Publications covers early developments in biocomputing

JMIR Publications

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(Toronto, May 28, 2026) JMIR Publications today released a feature story on the emerging field of biocomputing in its News and Perspectives section. Authored by science journalist Simon Spichak, MSc, “Biocomputing: Beyond the Hype” investigates how biotech companies like Cortical Labs and FinalSpark harness human brain cells to electrodes, performing computational functions and testing the cells’ responses to electrical and chemical stimuli. To create biocomputers, scientists grow organoids—small spheres of, in this case, neural tissue—on top of multi-electrode arrays in a hardware shell, which can then be used for everything from testing medications to playing video games. 

 

Uses for Biocomputers

While biocomputing technology is still nascent, early and potential applications are promising, Spichak reports; these uses include:

• Remote access for researchers: FinalSpark and Cortical Labs have both taken a cloud approach to their product delivery, providing researchers with remote access to their biocomputing hardware to run experiments.

• Energy-efficient computing: Biocomputing consumes far less energy than artificial neural networks and other conventional computational models; it also, according to Brett Kagan, PhD, Cortical Labs chief scientific officer and one of JMIR Publications’ expert sources, can learn with far less data and more chaotic data, compared to artificial intelligence.

• Drug discovery: Researchers have begun using biocomputing platforms to test the effects of different experimental medications on brain organoid learning. 

• Neuromorphic engineering: Johns Hopkins professor and expert source Thomas Hartung, MD, PhD believes biocomputing technology could potentially be used as a stepping stone for the development of neuromorphic systems: artificial neurons that mimic the structure and function of the human brain. 

 

Potential Bioethical Risks

Scientists have been taking a proactive approach to ethical concerns in biocomputing, consulting with bioethicists to address potential risks before they arise. “The brain organoids used for biocomputing,” Spichak writes, “raise similar concerns to stem cell and organoid research including the moral status and development of potential consciousness in more advanced models, informed consent from donors, and issues around commercialization, ownership and patents.”

 

The Future of Biocomputing

At the moment, biocomputing is limited by the unpredictability of the organoids’ activity, which complicates training. But as researchers’ understanding of this nascent field develops, biocomputing may have major implications for biomedical research.

 

Please cite as:

Spichak S. Biocomputing: Beyond the Hype. J Med Internet Res 2026;28:e100949

URL: https://www.jmir.org/2026/1/e100949

DOI: 10.2196/100949

 

About JMIR Publications News and Perspectives

JMIR Publications is a leading open access publisher of digital health research. The News and Perspectives section is the newest addition to its portfolio, established to bring the rigor and integrity of academic publishing to scientific journalism. The section features well-researched, expert-driven content from the Scientific News Editor, Kayleigh-Ann Clegg, PhD, and a network of specialist JMIR Publications Correspondents to keep the digital health community informed, inspired, and ahead of the curve.

 

About JMIR Publications

JMIR Publications is a leading open access publisher of digital health research and a champion of open science. With a focus on author advocacy and research amplification, JMIR Publications partners with researchers to advance their careers and maximize the impact of their work. As a technology organization with publishing at its core, we provide innovative tools and resources that go beyond traditional publishing, supporting researchers at every step of the dissemination process. Our portfolio features a range of peer-reviewed journals, including the renowned Journal of Medical Internet Research. 

 

To find out more about JMIR Publications, visit jmirpublications.com or connect with them on Bluesky, X, LinkedIn, YouTube, Facebook, and Instagram.

 

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The content of this communication is licensed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, published by JMIR Publications, is properly cited.

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Journal

Journal of Medical Internet Research

DOI

10.2196/100949 

Method of Research

Commentary/editorial

Subject of Research

People

Article Title

Biocomputing: Beyond the Hype

Article Publication Date

28-May-2026

 

Longer droughts and changes in rainfall are already occurring in the Amazon, research indicates

Recently published studies indicate an extension of the dry season from four to six months and an increase in the water deficit of more than 150 millimeters. These studies serve as a warning for 2026 and 2027, when a “super El Niño” is forecast.

Fundação de Amparo à Pesquisa do Estado de São Paulo

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Wildfires in Acre state, in the Brazilian Amazon 

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Credit: Beatriz Cabral

According to two recently published studies led by scientists from Brazil’s National Institute for Space Research (INPE), the Brazilian Amazon is already beginning to experience scenarios previously projected for the coming decades, including longer dry seasons and changes in rainfall patterns. Without integrated policies and initiatives to combat climate change, the situation could rapidly intensify, posing risks to biodiversity, the replenishment of natural water reservoirs, and the functioning of the forest.

The studies, which are based on climate models that incorporate regional dynamics, also serve as a warning for this year and next, as there is the possibility of a “super El Niño.” This phenomenon is characterized by the warming of the Pacific Ocean in the equatorial region. In its most intense form, it can raise temperatures by more than 2 °C above average, causing major changes in atmospheric circulation and rainfall patterns on a global scale.

One of the studies indicates that the dry season in the Amazon is lengthening from four to six months, with a water deficit exceeding -150 millimeters (mm) during that period. The article, published in the International Journal of Climatology, points to greater climate instability, more extreme events outside seasonal patterns, and increased forest degradation associated with fire.

Another study, which appears in the March issue of Perspectives in Ecology and Conservation, analyzes the drought recorded in the Amazon between 2023 and 2024, during which Brazil was heavily affected by El Niño. The findings reveal a 9% increase in burned areas and a 19% increase in forest degradation alerts, with up to 4.2 million hectares impacted by fire at the peak of the drought. These results demonstrate that the cycle of drought, fire, and degradation is intensifying and reducing the ability of the ecosystem to recover.

“A few years ago, when we started talking about climate scenarios for the Amazon, that future often seemed far off in the most pessimistic scenarios. However, we’re now observing the most pessimistic anomaly extremes occurring in the present. When we compare today’s data with the projections, we see how critical the situation is becoming as we include pessimistic scenarios in the climate analysis,” summarizes Débora Dutra, an environmental and sanitation engineer, doctoral candidate in remote sensing at the INPE, and the first author of the two articles.

Biologist Liana Anderson, Dutra’s advisor and a researcher at the INPE, highlights the role of scientists in light of the disconnect between the scientific evidence of the impacts of climate change on ecosystems and the responses to mitigate and contain them.

“We’re at a crucial moment with national and international goals to be met by 2030. If we direct our efforts in that direction, we can achieve them. We must view the connection between the environment, development, and the economy as an inseparable triad in terms of both exploitation and the cost of reconstruction following the impacts. I believe this climate crisis presents an opportunity to rethink our paths and accelerate sustainable initiatives that promote quality of life, social justice, and environmental justice. There’s mobilization within the scientific community to contribute and present alternatives. The question is, who’s willing to listen to what’s been studied over the past few decades?” adds Anderson, who leads Tropical Ecosystems and Environmental Sciences (TREES) alongside researcher Luiz Aragão. Aragão is also one of the authors of the articles.

Building models

In the research published in the International Journal of Climatology, the scientists used a metric that Aragão has been developing since 2007, the maximum cumulative water deficit (MCWD). MCWD is considered a key indicator of water stress in tropical ecosystems. The scientists combined the metric with data from phase six of the Coupled Model Intercomparison Project. This project provides a standardized framework for climate modeling aligned with the Shared Socioeconomic Pathways (SSPs) assessments of the United Nations Intergovernmental Panel on Climate Change (IPCC).

The study was conducted in the southwestern Amazon, covering the state of Acre and parts of the states of Amazonas and Rondônia. The region is home to areas with over 90% forest cover and is under intense pressure from deforestation.

The results show that under high greenhouse gas emission scenarios, water deficits intensify during the dry season in the Amazon, particularly in the southwestern portion of the forest. Projections indicate longer and more intense dry seasons with increased water stress between June and September, with deficits that could exceed -21 mm/month by the end of the century in the most pessimistic scenario.

This worsening trend will likely have direct impacts on the forest, including increased tree mortality, forest degradation, and biodiversity loss. It will also reduce the Amazon’s capacity to act as a carbon sink, which will reinforce a feedback loop between degradation and global warming.

To improve future projections and climate risk assessments in the region, the researchers suggest adopting integrated analyses that incorporate changes in land use, atmospheric circulation anomalies, and interactions between fires and droughts, among other measures.

In the study analyzing the extreme droughts of 2023 and 2024, the research team mapped and quantified water stress, forest degradation, and fire dynamics. They identified implications for environmental management. They concluded that the drought intensified the interaction between water deficits, fires, and degradation. Fires were increasingly associated with the weakening of standing forests rather than deforestation alone. Deforestation completely removes vegetation cover, whereas degradation weakens forests without destroying them entirely.

The results of the study highlight the need for integrated fire governance that combines climate indicators with early warning systems and strengthens institutional coordination. This governance must also incorporate forest degradation into mitigation and adaptation strategies.

Bridging science and practical initiatives

Under Anderson’s coordination, Dutra has studied the impacts of fire on the Amazon rainforest for several years and published an article on wildfires in the municipality of Boca do Acre in the state of Amazonas (read more at agencia.fapesp.br/40932). 

Since last year, the researchers have been part of the “Fire in Focus” initiative, a partnership between firefighting and prevention operational forces, such as the military fire departments of various states, and research institutions. To mark the launch of the program, the TREES laboratory, the Brasa Research Network, and the League of Military Fire Departments held an event in October 2025. There, they released the “Fire in Focus 2024-2025” report and the international article “State of Wildfires 2024-2025”. 

According to Anderson, the continuation of this joint effort with firefighters was authorized through 2026 in April. “This collaboration is a way to combine what science can deliver with the reality of those working on the front lines, in both prevention and firefighting strategies. We try to bridge science and action in society. But there’s still one area where we need to make progress: the magnitude of the economic impact and what that means for the country’s development,” says the researcher.

For this reason, Dutra decided to delve into the topic and will work on her doctoral thesis using data on the potential economic losses resulting from wildfires. Her thesis will address not only forestry issues, but also health and social impacts.

Dutra receives a scholarship from FAPESP, which also supported the two articles through five projects: 21/04019-4, 20/08916-8, 25/28244-8, and 25/07124-4. These projects include the Research Center for Greenhouse Gas Innovation (RCGI). 

About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe

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Journal

Journal of Climatology

DOI

10.1002/joc.70331 

Article Title

Dry-Season Water Deficits in the Southwestern Amazon Under High Emissions

Article Publication Date

29-Mar-2026

 

Which shocks pose the biggest risks to global food systems?

University of Oxford

 

Oxford study develops model to help countries identify vulnerabilities and outline measures to help strengthen resilience against food crises. 

 

Global food systems are fragile – recent shocks such as the closure of the Strait of Hormuz and the Russian invasion of Ukraine have raised prices and exacerbated food insecurity. Governments are increasingly trying to shield themselves from future food crises, whether caused by conflict, climate shocks, disruptions to global trade or failed harvests.

But new Oxford-led research suggests many countries may be focusing on the wrong kind of resilience. The findings challenge food-security strategies that focus mainly on increasing domestic food production while overlooking their dependence on shocks to production abroad and energy supplies. The conclusions are particularly relevant for countries such as the UK, where recent debates over food security have focused on improving self-sufficiency. 

The analysis, Assessing the Resilience of Global Grain Supplies to Compound Climatic and Non-Climatic Shocks, found that spikes in energy and fertiliser prices, such as those caused by the wars in Ukraine and Iran, can rapidly spread through global food systems because modern agriculture depends heavily on fuel, fertiliser and transport. Export bans and transport-related disruptions also caused severe regional impacts. 

Countries reliant on a narrow group of suppliers and holding low grain reserves were often hit hardest during severe global shocks. Extreme weather and poor harvests pushed food prices up by as much as 50 to 100 percent in some countries, depending on how exposed and diversified their food systems were. By contrast, countries with more diverse suppliers and flexible trade networks were better able to switch suppliers and cushion the impact of crop failures.

Jasper Verschuur, lead author and Research Associate at the Environmental Change Institute, University of Oxford, said: 'No country can build a fortress against global food shocks. And producing all food within your own border is unfeasible for many countries, and leaves them exposed to the vagaries of their weather. Countries with diverse suppliers, reserves and more flexible trade networks are often far better placed when crises hit'. 

The study highlights the importance on stress-testing the global food system and has developed a model which allows multiple simultaneous shocks to be analysed. In the most severe compound-shock scenarios, where poor harvests collided with wars, trade disruption and energy shocks, almost every country in the world experienced food-security losses simultaneously, though the impacts were distributed unevenly.

Professor Jim Hall, Director of the Oxford Martin Systemic Resilience Initiative at the University of Oxford, said: 'The real danger comes when shocks compound. A poor harvest, war or spike in fertiliser prices can now ripple rapidly through global trade networks and raise food prices far beyond the countries where the disruption began. What matters is not just how much food a country produces, but how prepared it is for instability'.

Key findings

• Global trade in food is essential to ensure global food security, and the food system needs to be stress tested to ensure it is resilient.
• This study has developed a modelling approach which can be a useful tool to locate countries’ food system strengths and vulnerabilities, and identify strategies to increase resilience.
• Energy and fertiliser price shocks often caused broader global impacts than direct trade disruptions because they affected producers worldwide simultaneously. 
• Extreme weather and poor harvests alone shifted global food prices by 10 to 15 percent but some countries experienced domestic food-price shocks of up to 50 to 100 percent. 
• Countries with diversified supply networks and bigger food reserves were often more resilient during moderate shocks whereas countries dependent on concentrated suppliers and low reserves were disproportionately affected during severe crises. 
• In the worst compound-shock scenarios, almost every country experienced food-security losses simultaneously although not equally. 

Notes to editors

The study, Assessing the Resilience of Global Grain Supplies to Compound Climatic and Non-Climatic Shocks, is published in PLOS Climate.

Authors and affiliations

• Jasper Verschuur — Environmental Change Institute, University of Oxford, UK; Delft University of Technology, Netherlands 
• Anna Murgatroyd — Environmental Change Institute, University of Oxford, UK; Newcastle University, UK 
• Yiorgos Vittis — International Institute for Applied Systems Analysis (IIASA), Austria 
• Aline Mosnier — Sustainable Development Solutions Network, Paris, France 
• Michael Obersteiner — Environmental Change Institute, University of Oxford, UK; International Institute for Applied Systems Analysis (IIASA), Austria 
• H. Charles J. Godfray — Oxford Martin School, University of Oxford, UK 
• Jim W. Hall — Environmental Change Institute, University of Oxford, UK

The analysis used a newly developed global trade model covering 177 countries and four major staple crops: wheat, maize, rice and soybean. It tested how climate-related crop failures interact with export bans, trade disruption and energy price shocks. 

The scenarios modelled were designed to test plausible global stress conditions rather than predict a specific future crisis. The analysis did not fully capture speculative trading, panic buying or emergency policy interventions, meaning some real-world price spikes could potentially become even more severe. 

Paper link:
https://journals.plos.org/climate/article?id=10.1371/journal.pclm.0000825

Media enquiries

Sara Davis
Communications and Media Manager
Oxford Martin School, University of Oxford
sara.davis@oxfordmartin.ox.ac.uk

About The Environmental Change Institute:

The Environmental Change Institute (ECI) conducts world-class, interdisciplinary research across eight core programmes: Climate, Energy, Ecosystems and Biodiversity, Infrastructure, Food Systems, Global Finance and Economy, Environment and Health, and Land, Society and Governance.

About The Oxford Martin Systemic Resilience Initiative:

The Oxford Martin Systemic Resilience Initiative aims to advance practical solutions to manage shocks with the potential for major and prolonged economic disruption, severe human or economic impacts, and contagion. It brings together academics specialising in biophysical modelling, risk analysis, transboundary resources and infrastructure, development, disaster preparedness and economics to reflect the high complexity and interdependencies of the systems involved.

About the University of Oxford

Oxford University has been placed number 1 in the Times Higher Education World University Rankings for a record-breaking tenth year running, and number 4 in the QS World Rankings 2026. At the heart of this success are the twin-pillars of our ground-breaking research and innovation and our distinctive educational offer.

Oxford is world-famous for research and teaching excellence and home to some of the most talented people from across the globe. Our work helps the lives of millions, solving real-world problems through a huge network of partnerships and collaborations. The breadth and interdisciplinary nature of our research alongside our personalised approach to teaching sparks imaginative and inventive insights and solutions.

Through its research commercialisation arm, Oxford University Innovation, Oxford is the highest university patent filer in the UK and is ranked first in the UK for university spinouts, having created more than 300 new companies since 1988. Over a third of these companies have been created in the past five years. The university is a catalyst for prosperity in Oxfordshire and the United Kingdom, contributing around £16.9 billion to the UK economyin 2021/22, and supports more than 90,400 full time jobs.

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Journal

PLOS Climate

DOI

10.1371/journal.pclm.0000825 

Similar timing and pattern: Seven European countries observe drop in chlamydia notifications especially among young people in 2024

After a decade of general increases in chlamydia cases across Europe, first signs of a decline suggest a possible common driver. Is it a true reduction and will it be a sustainable one?

European Centre for Disease Prevention and Control (ECDC)

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Chlamydia case notifications by country and year, 2015–2024 (n = 3,322,107). In 2024, all seven countries observed an overall decrease in chlamydia cases compared with 2023 for both males and females aged 15–45 years, with reductions ranging from 13% to 19%.

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Credit: Eurosurveillance

With more than 230,000 reported cases across the 27 European Union/European Economic Area (EU/EEA) countries in 2024, chlamydia is the most frequently notified sexually transmitted infection (STI) in the region. Since 2014, notification rates generally had been going up in most of the 20 countries in the EU/EEA with consistent reporting and comprehensive disease surveillance.

A first peak was reached in 2019, followed by a drop during the years of the COVID-19 pandemic. Chlamydia notifications bounced back up again in 2022 and went down again slightly in 2023.

Unexpected drop in chlamydia notifications in 2024
Beginning of 2025, Sweden shared a nation-wide decrease in notified chlamydia cases for 2024, via EpiPulse Events, a European Union event-based surveillance platform hosted by the European Centre for Disease Control and Prevention (ECDC). They also informed that this decline was mainly seen among young people despite unchanged testing policies.

Responding to this information, Denmark, England, Finland, Ireland, Norway and the Netherlands reported similar trends for 2024.

In their Euroroundup published in Eurosurveillance, Astorga Alsina et al. present an analysis of chlamydia notification data and trends between 2015 and 2024 for each of the seven countries that observed a decline in chlamydia cases during 2024. The authors also summarise hypotheses on potential drivers behind these. [1]

The described reductions in chlamydia cases in the seven countries were unexpected in their magnitude and evenly distributed geographically, i.e. the decline in case notifications was noted reporting across almost all subnational regions of the affected countries.

Denmark saw a drop of chlamydia case notifications by 19% between 2023 and 2024 (from 37,111 to 29,946 cases) with 17% and 22% declines in males and females, respectively. Case notifications declined between 12% and 32% across all regions.

In England, the number of recorded chlamydia cases went down by 13% in 2024 compared with 2023 (194,143 to 168,889 cases) – across sexes, age groups and regions. The largest decrease (18%) occurred among people aged 15-24 years. During this period, the total tests decreased by 1%. Since 2020, the possibility to order self-sampling tests online, has been the most common test setting among young people in England, surpassing tests by specialist sexual health services and general practitioners.

Finland had observed a steady increase in chlamydia cases in the years before 2024. Between 2023 and 2024, notifications fell by 17% from 17,551 to 14,486 cases. The decrease was noted in both males and females across age groups, mostly among those aged 20-24 years (-22%), and across 21 of 23 Finnish regions.

In 2024, Ireland observed a 16% decrease (from 13,699 to 11,524 cases) in chlamydia notifications across all health regions compared with 2023. Notably, among those aged 15-24 years, cases declined by 21% in both males and females, with the largest reduction of 28% among males aged 15–19 years. According to preliminary data for 2025, the trend continued into the first 6 months of the year. From 2023 to 2024, testing recommendations for chlamydia remained unchanged in Ireland with a national free home STI testing service introduced in June 2024.

The Netherlands recorded 20,174 chlamydia cases in 2024 compared with 24,048 in 2023, constituting a decline of 16% in one year. This decrease occurred across most age groups, notably among those aged 20-24 years (-21%) and was registered across all regions in the country. Overall testing went down as did test positivity.

With 18% fewer reported chlamydia cases in 2024 (down from 28,137 to 23,100), Norway saw a decrease across all counties, with notifications declining by 14% in males and 20% in females, respectively. The largest reduction was among those aged 20-24 years. Chlamydia testing activity decreased in 2024 in Norway, mostly due to fewer tests performed among people younger than 25 years.

In Sweden, chlamydia cases also dropped by 18% between 2023 and 2024, from 32,298 to 26,392 cases. Mainly younger age groups across both sexes accounted for this regression, with the largest reduction in those aged 20-24 years (-24%). There were no changes in testing practices, laboratory methods, public health interventions or campaigns that could explain the decrease in chlamydia in Sweden.

Testing volumes varied but test positivity overall decreased
In some countries, the decline in chlamydia notifications was accompanied by reduced testing: Denmark, England the Netherlands and Norway reported a decrease in overall testing volumes. England saw the largest reductions among people aged under 25 years particularly in online testing services.

The authors note that while changes in testing volumes varied, all countries observed a decrease in test positivity, suggesting a possible reduction in prevalence within the tested population.

Some of the countries saw decreases in other STI such as gonorrhoea while others saw stable or increased gonorrhoea reporting. Overall, however, the observed chlamydia decreases in all the countries were unexpected in their magnitude and generated several hypotheses.

Amongst other factors, the authors hypothesise about a collateral effect of targeted interventions addressing rises in gonorrhoea notifications which could have had a positive effect on chlamydia as well: “No major surveillance changes were identified and changes in testing policies targeting young people do not fully explain the observed declines. Possible drivers include a combination of sexual health promotion campaigns, changes in the risk profile of those accessing testing and long-term impacts of COVID-19. While variations across national contexts may favour country-specific hypotheses, the similar timing and pattern of the changes suggests a possible common driver.”

 

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References/notes to editors:
[1] Astorga Alsina Ana Martina, Gomes Dias Joana, Adlhoch Cornelia, Nerlander Lina, Olsen Anne Olaug, Igoe Derval, Hiltunen-Back Eija, Lyons Fiona, Velicko Inga, O'Donnell Kate, Folkard Kate, Crawford Katerina, Liitsola Kirsi, Visser Maartje, Wessman Maria, Neary Martha, Ferguson Miranda, Puolakkainen Mirja, Hoffmann Steen, Pedersen Thomas Roland, Hannila-Handelberg Tuula, Mårdh Otilia. Decreased chlamydia notifications in six European Union/European Economic Area countries and England, 2024. Euro Surveill. 2026;31(21). Available from: www.eurosurveillance.org/content/10.2807/1560-7917.ES.2026.31.21.2500846

[2] Most of the seven countries reporting on the decline in chlamydia cases during 2024 have comprehensive STI surveillance programmes in place, while the Netherlands employ a sentinel surveillance system collecting STI data from all national sexual health centres.

[3] For chlamydia data in 2024 covering EU/EEA countries, see also European Centre for Disease Prevention and Control. Chlamydia. In: ECDC. Annual Epidemiological Report for
2024. Stockholm: ECDC; 2026. Available from: https://www.ecdc.europa.eu/en/publications-data/chlamydia-annual-epidemiological-report-2024
 

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Journal

Eurosurveillance

DOI

10.2807/1560-7917.ES.2026.31.21.2500846 

Method of Research

Data/statistical analysis

Article Title

Decreased chlamydia notifications in six European Union/European Economic Area countries and England, 2024

Article Publication Date

28-May-2026