Cost-Effectiveness Analysis

Media Type Pricing

Meta Cloud API — Nigeria — Utility category — April 2026 — direct API, no BSP markup

Media type	Cost / message	Approx. data usage	Template complexity
Text	$0.014	< 2 KB	Simple copy — fastest approval
Audio	$0.014	50–200 KB	Requires audio file upload to Meta
Image	$0.014	50–150 KB	Requires image URL or uploaded handle
Video	$0.014	1–10 MB	Large download — not recommended for low-bandwidth

Channel cost comparison

Channel	Cost / message	Notes
SMS — Africa's Talking	~$0.0015	₦2.50 / message
SMS — Telerivet platform fee	~$0.0070	Per-message fee
SMS total (AT + Telerivet)	~$0.0085	Current baseline
Voice — Africa's Talking	~$0.0090	₦15 / min; ~1 min avg reminder
Voice — Telerivet platform fee	~$0.0070	Per-call fee
Voice total (AT + Telerivet)	~$0.016	Current voice baseline
WhatsApp — Meta Cloud API direct	$0.014	No BSP markup; all media types same price

A/B Test Design

All three arms have identical Meta cost per delivery attempt — the experiment adds zero incremental budget

Arm A

Text reminder

Written message with child name, vaccine name, and appointment date.

Metrics: delivery rate · appointment attendance · opt-out rate

$0.014 / msg

Arm B

Audio reminder

30-second voice recording. Meta reports "read" when the file is played — direct engagement proxy.

Metrics: play rate · recall · attendance · opt-out rate

$0.014 / msg

Arm C

Image reminder

Vaccination schedule card with appointment circled. High visual salience.

Metrics: image view rate · attendance · opt-out rate

$0.014 / msg

Randomisation and power

Design choice	Decision
Randomisation unit	Caregiver (not message — prevents within-caregiver confounding)
Min detectable effect at 5k / arm	~5pp at 80% power, alpha 0.05, baseline 60%
Min detectable effect at 3k / arm	~7pp
Primary outcome	Vaccination appointment attendance (requires outcome data linkage)
Secondary outcomes	WhatsApp delivery rate, read/play rate, opt-out rate

$/DALY Cost-Effectiveness Model

Formula: cost = caregivers × 7 reminders × $0.014 × overhead multiplier | DALYs = caregivers × uplift × 0.027 × 38

Caregivers reached 15,000

Vaccination uplift (percentage points) 18 pp

Overhead multiplier (total cost ÷ messaging cost) 150×

Program cost

—

total incl. overhead

DALYs averted

—

per year

Cost / DALY

—

GiveWell bar: ~$100

vs GiveWell bar

—

Model assumptions

Reminders per caregiver	7 (Nigeria EPI contact points)
Messaging cost	$0.014 / message (Meta Cloud API, Nigeria, Utility, April 2026)
VPD mortality rate (0.027)	Nigeria U5 mortality ~75/1000; ~35% vaccine-preventable attributable fraction
DALYs per death (38)	Child dying at age ~2; Nigeria life expectancy ~63; adjusted for disability weights
Overhead multiplier	Ratio of total program cost to messaging cost. Pilot: ~200–300×. At scale: target 50–100×.

Sensitivity Table

$/DALY by uplift and overhead multiplier — fixed at 15,000 caregivers, 7 reminders, $0.014/msg

≤ $100 — meets GiveWell bar

$101–$300 — promising; overhead reduction needed

> $300 — scale and efficiency improvements required