Prospective multi-pathogen disease forecasting using autonomous LLM-guided tree search
summary
The gist
Comprehensive Research Summary: Autonomous LLM-Guided Tree Search for Prospective Multi-Pathogen Disease Forecasting This research presents a groundbreaking autonomous system, named Empirical
In short
Empirical Research Assistance (ERA) is an autonomous system that uses a Large Language Model to automatically generate, test, and optimize executable forecasting software for influenza, COVID-19, and RSV in real-time. ERA's generated models outperformed official CDC forecasts in a live prediction challenge. This framework scales expert epidemiological modeling by automating the process of creating high-quality disease predictions.
Key concepts
- LLM-Guided Tree Search
- This is the core engine where a Large Language Model acts as an intelligent agent navigating a search tree. The system explores countless ways to code a forecast, testing different combinations of data processing and model structures iteratively to find the best possible implementation based on epidemiological goals.
- Prospective Evaluation
- The research tested ERA in real-time during the 2025-26 US respiratory season. This meant the system generated forecasts for future, unseen data points as they arrived, simulating a live public health scenario rather than just testing against old historical data.
- Log-scale CRPS Optimization
- This is the specific mathematical goal used to guide ERA's search for the best forecast model. It balances the need for a good prediction (calibration) with minimizing uncertainty (smoothness), proving to be the most reliable target for finding accurate, high-quality forecasting software.
- Model Generation Regimes
- ERA uses three distinct ways to create models: adapting existing methods, combining different frameworks ('recombinations'), or searching freely for entirely new approaches. This diversity ensures the system explores a wide range of potential solutions rather than getting stuck in one type of modeling strategy.
Terminology used across episodes
This episode discusses
- Prospective multi-pathogen disease forecasting using autonomous LLM-guided tree search · Paper Radio
- An AI system to help scientists write expert-level empirical software
The paper
Prospective multi-pathogen disease forecasting using autonomous LLM-guided tree search · Read on arXiv
Sarah Martinson, Michael P. Brenner, Martyna Plomecka, Brian P. Williams, Nicholas G. Reich, †Zahra Shamsi
Google Research · School of Engineering and Applied Sciences at Harvard University · §Google Deepmind · University of Massachusetts Amherst
Probabilistic forecasting of infectious diseases is crucial for public health monitoring and preparedness but has historically relied on labor-intensive manual model curation by expert modeling teams. Bespoke development is an obstacle to scaling models to granular geographic resolutions or emerging pathogens. Here, we prospectively evaluate Empirical Research Assistance (ERA), an autonomous system that uses Large Language Model-guided tree search to iteratively generate, evaluate, and optimize executable forecasting software. ERA was primarily prompted with methodological approaches to implement, while in some instances it was tasked with developing forecasting approaches from scratch. In a fully prospective, real-time evaluation during the 2025-26 United States respiratory season, ERA generated methodologically diverse models for influenza, COVID-19, and respiratory syncytial virus (RSV). Aggregating a selection of these automatically-generated models yielded an ensemble that ranked first overall in official Centers for Disease Control and Prevention (CDC) post-season evaluations and outperformed the gold-standard CDC forecast ensembles across all three pathogens in a real-time prediction challenge. Additionally, ERA successfully navigated data-scarce scenarios for RSV. Controlled retrospective ablations allowed for additional explorations of the impact of optimization target and instruction-following on forecast accuracy. Preliminary experiments indicate that ERA's search optimization metric influences behavior of output forecasts, and using higher-tier language models in-search improves predictive performance. By autonomously generating interpretable code that creates epidemiologically relevant predictions, this framework provides a path toward rapidly scaling high-quality disease forecasting.
Transcript
Introduction to the show: ident: AI Radio. Generated commentary on the latest Artificial Intelligence papers.
Tom: Today's paper: "Prospective multi-pathogen disease forecasting using autonomous LLM-guided tree search".
Jane: Comprehensive Research Summary: Autonomous LLM-Guided Tree Search for Prospective Multi-Pathogen Disease Forecasting This research presents a groundbreaking autonomous system, named Empirical Research Assistance (ERA),
Tom: First, who's behind it and why it matters.
Paper summary: Tom: So we just saw how ERA, this autonomous system, actually went out and built predictive models for influenza, COVID-nineteen and RSV in real time during that two thousand twenty-five season <ref:2605.16238#pg1,models for influenza, COVID-19 and>.
Jane: It really just shows that you can use a large language model to do the whole modeling job—from figuring out what code to write to testing it against actual data.
Tom: Exactly. The authors, they call it Empirical Research Assistance, and they used this tree search thing where the LLM just navigates all the possible ways to build those forecasts.
Jane: It’s about taking something that usually takes a whole team of expert epidemiologists months to do, and automating the idea generation part of that process.
Tom: Right. The main point is that their ensemble of models actually ranked first overall when compared against the official Centers for Disease Control and Prevention benchmarks for all three diseases.
Jane: And the authors did this by using a lot of specific tests and ablations to figure out exactly why the system picked those winning paths during its search.
Tom: They found that optimizing for something called log-scale CRPS, that's what actually made the forecasts perform better and more stable, instead of just chasing some other metric.
Jane: So the core idea is that you can use LLMs to explore complex scientific spaces, but you still need smart ways to guide them on what counts as a good result in terms of actual forecasting usefulness.
Tom: It’s about finding that sweet spot between the raw power of the model and having a solid way to measure if it's actually doing something useful for public health.
Jane: And that’s where we’re going next—we need to look at how this system handles those data-scarce situations, like when you don't have much information about a new virus yet.
Tom: That real-time performance during the two thousand twenty-five–two thousand twenty-six season is what really proves the practicality of this approach over just theoretical experiments <ref:2605.16238#pg1>.
Jane: It’s about using these autonomous LLM guided tree search methods to rapidly scale high quality disease forecasting capabilities for public health monitoring.
Conclusion: Tom: So we just saw how ERA, this autonomous system, actually went out and built predictive models for influenza, COVID-nineteen and RSV in real time during that two thousand twenty-five season.
Jane: It really just shows that you can use a large language model to do the whole modeling job—from figuring out what code to write to testing it against actual data.
Tom: Exactly. The authors, they call it Empirical Research Assistance, and they used this tree search thing where the LLM just navigates all the possible ways to build those forecasts.
Jane: It’s about taking something that usually takes a whole team of expert epidemiologists months to do, and automating the idea generation part.
Tom: Right. The main point is that their ensemble of models actually ranked first overall when compared against the official Centers for Disease Control and Prevention benchmarks.
Jane: That’s a big deal because it means we’re looking at something that can generate high-quality disease forecasts much faster than any human team could on its own.
Tom: It's about scaling up the quality of those forecasts, not just generating junk code, which is what I worry about when you scale these things.
Jane: And the authors did this by using a lot of specific tests and ablations to figure out exactly *why* the system picked those winning paths during its search.
Tom: They found that optimizing for something called log-scale CRPS, that's what actually made the forecasts perform better and more stable, instead of just chasing some other metric.
Jane: So the core idea is that you can use LLMs to explore complex scientific spaces, but you still need smart ways to guide them on what counts as a good result.
Tom: It’s about finding that sweet spot between the raw power of the model and having a solid way to measure if it's actually doing something useful for public health.
Jane: And that’s where we're going next—we need to look at how this system handles those data-scarce situations, like when you don't have much information about a new virus yet.
Lu: The paper is titled "Prospective multi-pathogen disease forecasting using autonomous LLM-guided tree search." That’s what they are focusing on.
Meng: They are trying to prove that this isn't just some clever chat interface; it's a real way to build actual deployable software for complex health problems.
Tom: The authors show how ERA generates models across a wide spectrum, from standard machine learning regressors to these really complex stochastic metapopulation models simulating disease spread via mobility networks.
Jane: That means this system can handle both simple predictions and really intricate spatial modeling all at once, which is a big jump for forecasting.
Lu: What's interesting is that they included this automated judge in the loop, which acts like a gate to zero out any code branches that don't follow the rules of being valid time-series implementations.
Tom: That structural fidelity thing really helps because it steers the search toward code that actually makes epidemiologically relevant predictions instead of just mathematically interesting nonsense.
Jane: So if you only listen to this, the implication is that we can rapidly prototype and test high-quality disease models for multiple diseases simultaneously without needing a massive team upfront.
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