# Vitamin A supplementation

**Intervention ID:** `int_vas`  
**Evidence strength:** very_strong  
**Causes:** `cause_nutrition`, `cause_global_health_life_saving`

## Mechanism

Periodic vitamin A for children under 5.

## Organizations in this catalog

- `org_nutrition_international`
- `org_helen_keller_intl`
- `org_givewell_top_charities_fund`
- `org_vitamin_angels`
- `org_unicef_malaria`

## Citations (public evaluator pages)

- https://www.givewell.org/charities/helen-keller-international
- https://www.givewell.org/charities/top-charities

## Evidence notes

GiveWell rates VAS evidence as very strong; many high-quality studies show impact though results vary by study (HKI review; Top Charities page).

## Key uncertainties

- Whether VAS remains as effective amid improved child health since older trials; some studies find small/no effects (GiveWell HKI review).
- Coverage surveys often cover only one campaign round / selected districts; potential non-representativeness (GiveWell HKI review).
- Wide variation / possible incomplete other-actor costs in some countries (GiveWell HKI review).

## Fungibility notes

GiveWell roughly estimates ~20–45% chance (by country) Helen Keller VAS funding would be replaced by other actors; adjusts CE downward accordingly (GiveWell HKI review).

## Cost-effectiveness notes (do not treat as verified without citation_urls)

GiveWell 2022-2024 avg ~$3500/life; ~$2/child-year (Helen Keller Intl).

Agents must look up `data/claims_index.json` and cite `citation_urls` before stating numbers.

## Provenance

See `docs/evaluation-provenance.md` and `data/graph/evaluations_graph.json`.

_last_reviewed: 2026-10-01_