On 25 March, President Biden set a revised target of 200 million vaccines administered within the first 100 days of presidency (more). As of 16 April, this target was met with a total of 202.28 million doses administered, including 3.35 million on that day (more). This is an extraordinary logistical effort, mirroring that seen in many countries around the world, but it does hide a deeper concern in the drive towards better protection against the virus.
Analysis by Bloomberg News indicates that demand is slowing with surplus supplies building up. Figure 2.3 sets out the proportion of vaccines delivered to different US states that have not yet been used.
Figure 2.3 – Percentage of vaccines doses delivered to individual US states but not used as at 12 April – compiled by Bloomberg News from data from Centers for Disease Control and Prevention
Source: Bloomberg News
All those over age 16 will be eligible for vaccination from April 19 (more), but this has been accelerated in a number of US states. The question is what steps can be taken to accelerate uptake. There are many factors in play that contribute to “vaccine hesitancy”, but one study by Dai et al. (more) has examined the impact of behavioural “nudge” strategies on vaccination rates.
In a series of RCTs, the study used text messages to make vaccination salient and ease the process of scheduling appointments. The RCTs concluded that a first text message boosted appointment rates and vaccination rates by 86% and 26% respectively, whilst a second reminder text provided a further boost of 52% and 16% respectively. The overall impact of the interventions increased vaccination uptake by of the order of 3.5 percentage points for effectively zero marginal cost.