Methodology

Pipeline overview

1. Ingest. A scheduled worker (node-cron, in-container) pulls each configured source on its declared cadence — weekly for CDC NNDSS, every 15 minutes for Google News and GDELT, etc.
2. Normalise. Each ingestor produces a uniform Signal shape: id, source, sourceCode, category, rank, title, summary, url, language, countryIso2, publishedAt, ingestedAt.
3. Resolve. News URLs are de-redirected (e.g. resolving Google News redirector links to canonical publisher URLs); language is detected; country is inferred from the source-feed metadata or text.
4. De-duplicate. Signals are keyed by canonical-URL hash; duplicates are merged with first-seen publishedAt retained.
5. Classify. Signals are tagged by category (official / news / surveillance / advisory) and rank (1 / 2 / 3) based on source.
6. Snapshot. A single JSON snapshot is written to a Docker volume (runtime-data/snapshot.json). The Astro server reads this file on each API request and caches with short TTL.

Country attribution

A signal is attributed to a country when:

• The source is country-scoped (e.g. GNEWS-ES-AR → Argentina), or
• The source explicitly tags the country in structured fields (CDC NNDSS state column → US; WHO DON country attribute), or
• The article title contains an unambiguous country name match against our country dictionary.

We deliberately do not attempt fine-grained named-entity recognition for country attribution from free text. The risk of misattribution outweighs the coverage gain.

Country level classification

The pin colour on the map encodes a level, not a count:

• Local — case, death, or active outbreak signal in the country.
• Imported — case present but exposure occurred elsewhere (returnee, repatriation, treatment).
• Response — only travel advisory, screening or quarantine policy signals; no local case.
• Inactive — no signals in the rolling 30-day window.

Levels are assigned by deterministic rules from the categorised signals; we do not use ML for this classification.

Freshness

• Fresh — last successful ingestion ≤ 60 min ago.
• Stale — 60 min – 6 h since last ingestion.
• Unknown — no successful ingestion yet.

What we don't do

• We do not estimate or extrapolate case counts. Numbers shown reflect signal mentions, not confirmed cases. Confirmed cases come from official surveillance feeds and are clearly labelled.
• We do not use generative-AI summaries for headlines. We display the publisher's title verbatim.
• We do not store article body text. We link to the source.
• We do not track users.

Open data

The complete signal feed is available at /api/signals.json under CC BY 4.0. Country-level summary at /api/countries.json. Source health at /api/health.json. RSS at /feed.xml.