Do celebrity endorsements like Keir Starmer's HIV test affect public health?

Sir Keir Starmer has become the first sitting UK Prime inister to publicly take an HIV test to reduce stigma around Aids and encourage more people to get tested.

His attempt to lead by example has been likened to Elvis Presley being photographed receiving the polio vaccine at CBS Studio 50 at the height of his fame.

But do these high-profile gestures really change attitudes and behaviour? Or are they just headline-grabbing stunts that make the individual look good?

A closer look at the behavioural science behind celebrity endorsements suggests that, under the right conditions, public demonstrations by famous figures can indeed shift social norms, reduce stigma and influence health outcomes.

However, the effects depend a lot on the credibility of the endorser, the authenticity of the act, and the presence of sustained, follow-up campaigns.

Elvis’ polio jab remains one of the most iconic examples of celebrity-led health campaigns. Yet many other well-known figures have encouraged the public to adopt protective health measures, from actors promoting annual flu jabs to footballers advocating organ donation drives.

The premise is that a celebrity’s endorsement can normalise certain behaviour by tapping into the principles of  'social learning theory', particularly observational learning. In other words, when we see someone we admire or trust do something, we are more likely to follow suit.

In the 1950s, polio was a serious threat, capable of causing paralysis or death. After seeing images of Elvis rolling up his sleeve to receive the jab, many teenagers – previously sceptical or apathetic – became far more willing to accept the polio vaccine. That event is now hailed as a masterclass in leveraging popular culture to address a public health crisis.

A cornerstone of behavioural science is the recognition that who delivers a message can be as important as – or sometimes more important than – what the message contains. The so-called 'messenger effect' highlights how we are often more persuaded by people we perceive to be credible, relatable or high status.

Can the Prime Minister nudge us to behave better?

In the case of Elvis, he was already idolised by millions. He was the perfect conduit to promote vaccination among teenagers who might otherwise dismiss appeals from older authority figures.

Starmer occupies a different kind of influence. Supporters of the Labour party may see him as a trustworthy figure, while others could be sceptical of a politician’s motives. This underscores a key aspect of the messenger effect: if a large segment of the target audience views the figure as partisan or self-serving, the endorsement can backfire or simply fail to register.

Another powerful effect identified in behavioural science are social norms – our shared understanding of what is typical or appropriate – which strongly influence whether we take certain actions.

Stigma around HIV remains a major barrier to testing and treatment. Even though medical advances have changed the landscape of HIV/Aids care, many people still fear the societal consequences of a positive diagnosis.

According to the UK Health Security Agency, around 5,000 people in the UK are unaware they are living with HIV, partly because they hesitate to test in the first place.

By publicly taking an HIV test, Starmer aimed to shift perceptions and normalise testing. In terms of social identity theory, seeing a prominent figure within the national community – especially one involved in shaping policies – undergo testing can communicate that 'people like us' view HIV testing as a routine, responsible health measure.

This may be particularly powerful for people who identify politically with Starmer or who respect his leadership position.

Despite the potential of celebrity or high-profile endorsements, behavioural science also points to authenticity as a vital ingredient. Audiences are more likely to change their behaviour if they believe the celebrity genuinely cares about the issue rather than simply seeking publicity.

How did Elvis Presley change public behaviour?

If endorsements are perceived as insincere or politically opportunistic, their effect can be muted or even counterproductive.

In Elvis’ case, he was known for engaging with young fans and had a track record of doing work for public good, which helped bolster the sense that his polio vaccination was done for more than just a publicity boost.

For Starmer, sustaining the momentum beyond a single test – through continued advocacy, support of free testing programmes, and visibility in HIV-awareness campaigns – could reinforce the perception of a real commitment rather than a fleeting photo opportunity.

Behavioural scientists also often talk about 'nudges' – small interventions that change people’s choices without forbidding options or significantly changing incentives. A celebrity endorsement can serve as a nudge by making a desirable health behaviour (like getting tested) more top-of-mind or socially acceptable.

However, historically, Elvis’ vaccination was not a standalone act. It was part of a broader public health strategy involving schools, local campaigns and continued outreach. Those elements ensured that once people were motivated to get the polio jab, they could do so easily.

For HIV testing, the same principle applies: visible leadership from Starmer may spark initial interest, but practical measures – such as pop-up testing centres, free home-test kits and confidential testing support – are vital to maintain engagement.

Is Keir Starmer the new Elvis? In reality, the two scenarios differ in time and context. A 21st-century political leader raising awareness about HIV testing in the UK operates within a more complex media landscape than a 1950s rock 'n' roll icon appearing in national newspapers.

Yet there is a parallel: both used their public status to tackle a widespread health concern, hoping to overcome stigma and promote an important preventative measure.

Ultimately, celebrity moments can open the door, but only a sustained, evidence-based strategy will keep it open – and encourage people to walk through. With that in mind, it's worth noting that anyone in England can order a free and confidential HIV test to do at home.

This article was adapted from the original version published by The Conversation.

Further reading:

Three ways nudging can improve health outcomes

How smiling can help leaders

Are reminders better than financial incentives for patients?

The hidden cost of discrimination in everyday transactions

Ivo Vlaev is Professor of Behavioural Science and served as an Advisor for the NHS COVID-19 Behaviour Change Unit. He teaches Behavioural Sciences for the Manager on the Executive MBA, Full-time MBA, and Global MBA programmes. He also teaches on a range of Undergraduate and Master's programmes.

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