Every series on the country and disease pages carries a grade from A to D. The grade is about the data, not the country or the programme: it says how much to trust the number and why. The rules are mechanical and printed here so they can be checked; the facts behind each grade are in the row's tooltip and in the downloadable JSON.
Coverage series (country × vaccine)
Start at A. Then, over the last 10 years:
- Missing WHO/UNICEF estimates: 1–2 years missing drops one grade; 3 or more drops two.
- Gap between the WHO/UNICEF estimate and the country's own administrative figure: an average gap above 10 points drops one grade; above 20 drops two. No administrative figure to compare drops one.
- Any year where the country reported coverage above 100% (a denominator problem) drops one grade.
- Latest estimate more than a year old drops one grade.
- No WHO/UNICEF estimate at all, only the country's own figure: D.
Reported-case series (country × disease)
- Reported in all of the last 10 years: A. 7–9 years: B. 4–6: C. 1–3: D. None: no grade.
- Zero cases every year while the rest of the WHO region reported cases drops one grade; it may be elimination, or it may be silence.
- Latest report more than a year old drops one grade.
- Every case series carries the same caveat: reported cases undercount true infections, by an amount that depends on testing and surveillance.
What the grade does not know
- It does not see the WHO/UNICEF "grade of confidence" or survey evidence behind an estimate; those live in the WUENIC country reports.
- It does not see surveillance-quality indicators (rate of discarded cases, share lab-confirmed) for measles and rubella; those are in WHO's measles surveillance datasets and are a planned addition.
- It does not adjust for population size or for diseases that are not notifiable in a country.
Sources and build
- WHO Immunization Data Portal exports (coverage, reported cases, incidence rates, vaccine schedules), downloaded 21 October 2026. File hashes are in MANIFEST.json.
- CDC SchoolVaxView kindergarten coverage and exemptions, for the United States page.
- Pages are generated by a script from those files; the script is published in the site repository as scripts/build_epi.py.