Interventions to increase vaccine uptake among socially excluded groups: A systematic review

Background:

There are known inequalities in vaccine uptake and the distribution of vaccine-preventable diseases. Understanding the best ways to increase vaccine uptake among socially excluded groups is vital to reduce these inequalities.

Aim:

To assess the effectiveness of interventions to increase vaccine uptake among socially excluded groups.

Methods:

Systematic review of randomised controlled trials (RCTs) and non-randomised studies of interventions. Studies were eligible if they evaluated an intervention to increase uptake of any vaccination on the World Health Organization immunisation schedule and focused on socially excluded populations (e.g. people experiencing homelessness, people who use drugs). MEDLINE, Embase and PsycINFO were searched to January 2025. Risk of bias was assessed using Cochrane risk of bias tools. Data were analysed using random-effects meta-analyses and effect direction plots.

Results:

Of 2673 records, 20 studies were eligible (18 RCTs and two non-randomised studies). Most (13 studies) were conducted among people who use drugs and investigated hepatitis B (HBV) vaccination uptake (16 studies). Various interventions were identified: accelerated HBV vaccination schedules (six studies); financial incentives (four); educational initiatives (two); motivational interviewing (two); post-natal home visits (one); enhanced outreach and on-the-spot vaccination (one), and four varying interventions delivered as part of care co-ordination or nurse-guided case management models. Nine studies were at high risk of bias, six had some concerns and five were at low risk.

Meta-analyses indicated a potential beneficial effect of accelerated schedules (odds ratio (OR):1.45, 95%CI:1.10–1.91) and financial incentives (OR:5.36, 95%CI:2.61–11.01). Confidence in the evidence was judged to be ‘moderate’ for both these interventions. Evidence for the effectiveness of other types of interventions was inconclusive.

Conclusion:

We identify some promising strategies for improving uptake of vaccinations among some socially excluded groups. The conclusions that can be drawn are, however, limited by the lack of high-quality studies on the topic.