# Covidex: Neural Ranking Models and Keyword Search Infrastructure for the COVID-19 Open Research Dataset

arXiv: https://arxiv.org/abs/2007.07846 · HTML: https://mlsanity.com/paper/2007.07846/

## Key facts

- Cited by 15 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 14 Jul 2020.

## Built on by (most cited first, 15 of 15)

- [The Expando-Mono-Duo Design Pattern for Text Ranking with Pretrained Sequence-to-Sequence Models](https://mlsanity.com/paper/2101.05667/) (2021)
- [Neural Natural Language Processing for Unstructured Data in Electronic Health Records: a Review](https://mlsanity.com/paper/2107.02975/) (2021)
- [The ROOTS Search Tool: Data Transparency for LLMs](https://mlsanity.com/paper/2302.14035/) (2023)
- [MS MARCO: Benchmarking Ranking Models in the Large-Data Regime](https://mlsanity.com/paper/2105.04021/) (2021)
- [Modeling Multi-hop Question Answering as Single Sequence Prediction](https://mlsanity.com/paper/2205.09226/) (2022)
- [COVID-19 Named Entity Recognition for Vietnamese](https://mlsanity.com/paper/2104.03879/) (2021)
- [GAIA Search: Hugging Face and Pyserini Interoperability for NLP Training Data Exploration](https://mlsanity.com/paper/2306.01481/) (2023)
- [Multistage BiCross encoder for multilingual access to COVID-19 health information](https://mlsanity.com/paper/2101.03013/) (2021)
- [Spacerini: Plug-and-play Search Engines with Pyserini and Hugging Face](https://mlsanity.com/paper/2302.14534/) (2023)
- [SciEv: Finding Scientific Evidence Papers for Scientific News](https://mlsanity.com/paper/2205.00126/) (2022)
- [NeuralSearchX: Serving a Multi-billion-parameter Reranker for Multilingual Metasearch at a Low Cost](https://mlsanity.com/paper/2210.14837/) (2022)
- [Interpretable Self-supervised Multi-task Learning for COVID-19 Information Retrieval and Extraction](https://mlsanity.com/paper/2106.08252/) (2021)
- [Composable NLP Workflows for BERT-based Ranking and QA System](https://mlsanity.com/paper/2504.09398/) (2025)
- [Enhancing Document Retrieval in COVID-19 Research: Leveraging Large Language Models for Hidden Relation Extraction](https://mlsanity.com/paper/2506.18311/) (2025)
- [Getting Your Indices in a Row: Full-Text Search for LLM Training Data for Real World](https://mlsanity.com/paper/2510.09471/) (2025)

## Abstract (arXiv)

We present Covidex, a search engine that exploits the latest neural ranking models to provide information access to the COVID-19 Open Research Dataset curated by the Allen Institute for AI. Our system has been online and serving users since late March 2020. The Covidex is the user application component of our three-pronged strategy to develop technologies for helping domain experts tackle the ongoing global pandemic. In addition, we provide robust and easy-to-use keyword search infrastructure that exploits mature fusion-based methods as well as standalone neural ranking models that can be incorporated into other applications. These techniques have been evaluated in the ongoing TREC-COVID challenge: Our infrastructure and baselines have been adopted by many participants, including some of the highest-scoring runs in rounds 1, 2, and 3. In round 3, we report the highest-scoring run that takes advantage of previous training data and the second-highest fully automatic run.