Incentives for childhood vaccination

What the evidence says

Two large randomized trials found big gains. In rural Rajasthan, India, where few children were fully immunized, Banerjee and colleagues (2010) compared reliable monthly immunization camps with and without small in-kind incentives, lentils and metal plates. By the end of the study, 39 percent of children in incentive villages were fully immunized, compared with 18 percent where camps ran without incentives and 6 percent in control villages. Each immunization cost about $28 with incentives and $56 without.

In northwest Nigeria, IDinsight ran a cluster-randomized trial of a program that pays caregivers small cash incentives at vaccination visits. It raised full immunization by 27 percentage points, and coverage of individual vaccines by 14 to 21 points. Coverage also rose by about 20 points in control communities over the same period. GiveWell’s 2024 model assumes a smaller gain of 9 to 18 points, depending on location.

Where coverage was already high, the effect was smaller. In a Kenyan trial, text-message reminders plus an incentive of 200 shillings raised full immunization by age one from 82 percent to 90 percent.

The evidence is not uniform. A 2023 Cochrane review, drawing on studies from Mexico, Honduras, Nicaragua and Zimbabwe, rated the evidence on household monetary incentives very low certainty and could not say whether they improve vaccination. Charitology grades the evidence moderate: strong trials show large effects in some settings, the effect varies a great deal with context, and a systematic review of other incentive studies found no clear benefit.

Where it sits on the depth scale

Incentives are prevention (depth 2). The reward raises vaccine uptake, and the vaccines prevent disease in the children who get them. The reward has to keep being paid, and on its own it doesn’t fix supply problems such as unreliable clinics or vaccine stock-outs, though facilities in the Nigerian program reported fewer stock-outs than control facilities. The India trial suggests both sides matter: reliable camps alone tripled full immunization over control villages, and incentives roughly doubled it again.

Open questions

• How much of the measured rise would have happened anyway? Coverage rose sharply in the Nigerian control areas too. See the counterfactual problem.
• Do families keep vaccinating younger children once the payments stop?
• Do the large effects in India and Nigeria carry over to places where most children are already vaccinated?