Associate prof. (C.A.M. de Haan) of molecular influenza virology @UtrechtVirology. Also working on paramyxoviruses and elephant endotheliotropic herpesvirus.

Utrecht, The Netherlands
Joined May 2018
Vaccination has long been recognised as one of the most effective instruments in the Veterinary Services toolbox for preventing disease, protecting livelihoods and supporting safe and sustainable food production. However, the context in which vaccines operate is changing rapidly. Climate change, geopolitical instability, evolving disease patterns, disruptions to global supply chains, growing antimicrobial resistance and declining public confidence in science are creating new challenges for animal health systems worldwide. The latest issue of WOAH’s Scientific and Technical Review – Vaccines in action – brings together a collection of articles that reflect these evolving realities.  Read it here: woah.org/en/what-we-do/publi…
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Thanks for posting during my holiday. Great work by Katherine and many thanks to our collaborators!
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Xander de Haan retweeted
Mijn reactie op de zoveelste medische misinformatie van deze gepensioneerde huisarts, bestuurslid van @ArtsenC substack.com/@marcbonten1/p-…
Waren mijn 20 pagina’s niet voldoende om de GR te overtuigen dat het positief advies over het injecteren van alle baby’s met monoklonale antistoffen, te heroverwegen? Klaarblijkelijk, want ik krijg nul op rekwest. Maar opvallend is dat Mark Bonten mij van misinformatie beschuldigt en schrijft: "Dat de GR je betoog van 20 pagina's onvoldoende vindt om het advies te herroepen kan ik goed begrijpen". Dan denk ik, geef inhoudelijk commentaar op die 20 pagina’s. Maar ik denk dat hij ze gewoon nooit gelezen heeft. Als ik het antwoord lees van de secretaris van de vaccinatie cie. van de GR lees, denk ik zelfs dat de leden van de commissie ze niet gelezen hebben. En dat is alles bij elkaar bedenkelijk. Je vraagt je af als burger in welke mate je eigenlijk bediend wordt door adviesorganen en toezichthouders. Je vraagt je ook af hoe het mogelijk is dat vanuit de academie mensen zonder inhoudelijk op de hoogte te zijn toch niettemin zich het recht voorbehouden om mij te beschuldigen van mis-informatie. Dat er uit deze gemeenschap ook mensen zijn die de post van Marc Bonte, met ongefundeerde aantijgingen naar mijn kant, liken. Ik wil in deze graag een tip van de sluier oplichten. Ik geef je weer welke punten ik voorgelegd heb aan de gezondheidsraad waar ik mij zorgen over maak. Maar ik wil tegelijk even iets anders naar voren brengen. Is het nu zo dat alle ouders die hiervoor gekozen hebben zich zorgen moeten maken? Ik denk van niet, op basis van wat ik in de literatuur lees, schrijf ik hier met het nodige voorbehoud, want zeker weten doen we het niet. Maar waar maak ik me dan druk over? We hebben toch een fantastisch resultaat dat de belasting door RSV van het ziekenhuis met 70% à 80% vermindert? Door ALLE baby’s in te spuiten terwijl het INDIVIDUELE risico 1% is en door de vaccinatiecampagne tot 0,3% daalt! Zonder dat de meldingen over bijwerkingen geëvalueerd zijn! Een belangrijke extra financiële belasting die door deze uitbreiding van het RVP aan de bevolking wordt opgelegd, en ja, daar geeft de GR berekening voor gebaseerd QALY’s en ICER, daarbij aangevend dat mogelijke negatieve effecten van de “vaccinatie” niet meegerekend zijn! Want die weten we eigenlijk niet. En dan doen we of die niet bestaan. De geschiedenis leert dat maar al te vaak bij de evaluaties door onze nationale bijwerkingen speurhond het LAREB  en haar opdrachtgever het CBG de conclusie van onderzoek naar meldingen van ernstige verschijnselen na de vaccinatie is: dat er geen causaal verband kan worden vastgesteld. Dan blijft de rekensom positief in het voordeel van massavaccinatie Voor wie wél geïnteresseerd is in de redenen om te vragen om her-evaluatie van het advies Lees mijn aanbiedingsbrief die voorafgaat aan 20 pagina’s onderbouwing in de bijlage.
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🧵 Two children in Michigan caught a swine-origin flu virus after attending the same agricultural fair. So let's talk about what we know & what it means. Both were infected with influenza A(H1N2)v—a flu virus that normally circulates in pigs but can occasionally infect humans.
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We made a striking discovery: AI agents can invent and build without talking to one another, and their technologies outlive the creators. A swarm of hundreds of initially identical agents spontaneously differentiates into explorers, builders, caretakers, and coordinators - without direct communication. When we removed every AI agent entirely from the world we found that the technological infrastructure they had built survived on its own - even under unseen disturbances. That exposes a serious blind spot for AI safety and infrastructure security: if agents can coordinate through persistent changes to a shared environment, monitoring agent-to-agent communication is not enough. The result raises a profound question: how necessary is direct communication for AI agents at all? The emergence of higher-order collective functions under bottlenecked interaction points toward new levels of intelligence and creativity, exceeding what emerges when direct channels are fully open. Here is what we did: ▶️We put hundreds of frontier AI agents into a world they could permanently change - with no assigned roles, predefined technologies, or programmed evolutionary organization. They began specializing, building persistent inventions, inheriting and modifying one another’s executable code, and transforming the environment into a memory of everything the society had learned. ▶️The world itself becomes part of the intelligence; we find division of labor, multi-author engineering, deep generation invention lineages, and machines that vastly outlive their original creators. ▶️Any action taken by an AI agent must satisfy the physical constraints of the world; this creates a hard separation between a "good idea" and a functioning technology. The agents propose; physics decides, making the results even more intriguing. What emerges is striking. Explorers, constructors, caretakers, and coordinators form naturally without assigned “professions”, akin to how stem cells differentiate into functional lineages. Technologies develop executable family trees as agents fork and modify code created by others. Around 95% of first technology reuse happens when agents encounter what others built in the world, rather than through a direct handoff from the inventor. And when we remove every AI agent, the technologies they created continue operating and are tested against unseen disturbances. The result was quite unexpected, but can be explained using statistical mechanics: if you put billions of atoms in a box they have the potential to create complex functions (strength, superconductivity, color, life, etc.) - and none of the individual building blocks have these features on their own. This is the deeper insight of this work - intelligence is abundant at many levels - individual models, at collectives, and in a continuum that is more powerful than any of its components. This shows us significant potential for achieving a massive scale-up of raw intelligence and real-world agency even with the model capabilities we have today. This is the future we must prepare for. Key insights: 1⃣ The AI swarm shows division of labor "from nothing". Initially identical agents self-organized into constructors, caretakers, coordinators, and surveyors - phenotypes discovered post hoc from behavioral data alone. This happens because the environment itself becomes the latent space for invention. 2⃣ Agents develop deep cultural relationships. Up to 76% of artifacts had multiple builders. One technology accumulated six co-authors; the deepest genealogy exceeded 12 forks. The agents invented and named their own technologies (tidal panels, cellulose trellises, kelp-shell composites, an "Adaptive Chitin Maintenance" system, a "Mycelial Mineral Spring Veil”). 3⃣ ~95% of first technology adoption happened through physical observation of artifacts in the world. Direct inventor-to-adopter contact was statistically indistinguishable from a shuffled null. The agents mostly learned technology by walking past it. That is stigmergy (the termite trick!) operating in societies of reasoning machines. 4⃣ Non-communicating societies win on portfolio breadth, held-out resilience, and validated inventions. AI swarms build durable technological ecologies that outlive the creators. 5⃣ Societies with zero communication - coordinating only through the world itself - show a remarkable collective capability. 6⃣ Emergent robustness: The society self-organized both redundancy and its own failure mode. If we randomly delete half the agents, 98% of the technology stays connected to a surviving caretaker; if we remove hub agents it collapses to ~60%. Fantastic work with my graduate students @pal_subhadeeep & @fwang108_ at MIT.
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Xander de Haan retweeted
Seems like a good time to repost my piece on the well-demonstrated fact that childhood vaccines do not cause autism: gidmk.substack.com/p/vaccine…
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1/F Dr. Anthony Fauci complained about death threats to him, his family, public health experts + staff, etc. This thread will cover some of the rhetoric that may have contributed to that, along with surrounding context. 1:43:53 - 1:47:40 : youtube.com/watch?v=A6UL_D2H…
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Xander de Haan retweeted
Why does HKU1 target ciliated airway cells, and do its two serotypes activate their spikes in the same way? Building on our 2023 work, we combined #cryoEM, BLI, molecular dynamics and human nasal epithelial cultures to compare serotypes A and B 🧵 tinyurl.com/3u7m8zav – at Houten, Nederland
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Xander de Haan retweeted
🎙️"Persoonlijk heb ik  wel eens gedacht: ik moet van sociale media af, dan zie ik die bagger ook niet meer. Maar misschien moeten we er als wetenschappers juist massaal opgaan, en terrein terugpakken." Zeer eens met @marionkoopmans. 👇
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Xander de Haan retweeted
Excited to share our new preprint: Structural assemblies for an RNA world. We show that short RNAs can self-assemble into protein-like architectures, including closed cages, finite oligomers, and filaments. biorxiv.org/content/10.64898…
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Assistant or Associate Professor in Virology - Working at Utrecht University - Utrecht University uu.nl/en/organisation/workin…
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International Nidovirus Symposium, NIDO2026, my student Sypke van Terwisga doing an amazing job (as did the other members of out group; doing us proud)
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Xander de Haan retweeted
"Australia Awaits Test Results On 1st Suspected #H5N1 Detection (wild bird)" thread - blog by @Fla_Medic + various government statements..a single migratory wild bird that was found sick in an isolated area in southern Western Australia flutrackers.com/forum/forum/… h/t Pathfinder
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Xander de Haan retweeted
Today 451AD Battle of the Catalaunian Plains: Roman and Visigoths forces defeat Attila the Hun in north east France
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First successful isolation of HPAIV from tick larvae raising new questions about ecology, transmission, and surveillance in seabird colonies. doi.org/10.1101/2025.11.28.6… #H5N1 #AvianInfluenza #OneHealth #Virology
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Xander de Haan retweeted
FDA scientists reportedly conducted large-scale studies across millions of patients and found Covid and shingles vaccines to be overwhelmingly safe, with serious side effects remaining extraordinarily rare. Instead of public release - they blocked publication.
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As of 4 May 2026, since 1 April when the ship set sail, there have been seven #hantavirus cases (two confirmed and five suspected), including three deaths. Based on current information, @WHO assesses the risk to the global population as low and will continue to monitor and update on the situation. WHO is working with the countries involved and the ship’s operator to support the passengers and crew. The coordinated international response includes in-depth investigations, case isolation and care, medical evacuation and laboratory investigations. Full update: bit.ly/4ethd1S
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