Halo Trial
Research type
Research Study
Full title
Reducing sexually transmitted infections amongst those at highest risk: The Halo randomised controlled trial
IRAS ID
352986
Contact name
Katie Newby
Contact email
Sponsor organisation
University of Hertfordshire
Duration of Study in the UK
3 years, 3 months, 31 days
Research summary
There were 401,800 diagnoses of Sexually Transmitted Infections (STIs) in 2023, and 45% of those were from people aged 15-24 years. The only way for sexually active people to avoid STIs is to use a condom, but young people often report not doing this.
More young people are now using STI testing websites, but these websites do not offer much advice on how to prevent future infections. Together with young people and health professionals, we developed a digital intervention called Halo which aims to support young people to use condoms properly every time they have sex and reduce future STIs.
We want to know whether Halo works. To do this we need to run an experiment called a Randomised Controlled Trial (RCT). We will recruit 3,576 users of STI testing websites, aged 16-24 years. Participants will either get usual STI prevention information offered by STI testing websites, or this usual information plus Halo. Participants will take an STI test for chlamydia and gonorrhoea using a self-sampling kit at the start of the trial, then 3 and 12 months later. They will also complete surveys asking about STI diagnoses, condom use and quality of life at the start and 3, 6 and 12 months later.
The information from both groups will be compared to see if Halo increases condom use and reduces STIs, including amongst those in higher risk groups. We will compare the costs and benefits of each approach.
A young people’s advisory group, co-facilitated by two young co-applicants, will advise us throughout.
The results will be published in a research journal. We will share our findings with researchers, people who make decisions about sexual health services, young people and the public. If Halo works, we will try to get it offered to all young people who use STI testing websites.
MONETARY INCENTIVE STUDY WITHIN A TRIAL (SWAT)
This SWAT (Study Within A Trial) evaluates whether offering participants a choice of gift vouchers from different retailers improves recruitment and retention rates in the Halo Trial, compared to not offering a choice (i.e., offering a single type of gift voucher only). It also examines the cost-effectiveness of this approach.Monetary incentives—such as gift vouchers—are commonly used in trials to support recruitment and retention. While they have the potential to enhance participation, the existing evidence is limited and of low quality. It remains unclear whether allowing participants to choose their voucher type has a measurable impact, particularly among younger people, who may hold strong preferences based on social, environmental, and ethical values when deciding where to shop.
Priority setting exercises - including by the Implement SWATs team and the International Trial Forge SWATs Network, which involved patient and public partners, have identified monetary incentives as key strategies to test for their effectiveness for recruiting and retaining participants.
Potential participants invited into the Halo Trial will be randomly assigned to be offered a choice of gift voucher incentive from one of three retailers, Amazon™, Life:style or EdenRed (intervention) or no choice (Control group. Given the standard Amazon™ voucher).
The primary outcome is numbers randomised in the Halo trial. The numbers of participants retained in the Halo Trial and cost-effectiveness will also be assessed.
REC name
London - Central Research Ethics Committee
REC reference
25/LO/0479
Date of REC Opinion
12 Aug 2025
REC opinion
Further Information Favourable Opinion