Outbreaks of preventable diseases, like polio and measles, are on the rise. According to the World Health Organization (WHO), the number of countries with significant measles outbreaks rose by 50% between 2020-21 and 2022-23, and measles has re-emerged in places where it had previously been eradicated. This happens when vaccination rates drop below a certain threshold, compromising the herd immunity that was achieved through decades of vaccination programmes. 

This is partially due to disruptions to childhood immunisation schedules caused by the COVID pandemic, conflict and humanitarian crises. However, another key factor is vaccine hesitancy, the reluctance or refusal to accept available vaccines. 

In 2019, vaccine hesitancy was identified by WHO as one of the ‘top ten threats to global health’.

And a recent UNICEF report indicated that overall confidence in the importance of vaccinating children had decreased since the COVID pandemic.  

A holistic approach

In my work as a pharmaceutical scientist, it is just as critical to understand how people perceive vaccines and why they may distrust them as it is to ensure the vaccines themselves are safe and effective. 

Vaccine hesitancy is influenced by a vast range of factors including socioeconomic conditions, cultural and religious beliefs, accessibility, misinformation, mistrust of governments and pharmaceutical companies, and political ideology. 

Consequently, our team at UCL takes a uniquely holistic approach – one that integrates scientific advancements in vaccine development with social science research and interventions. By studying vaccine hesitancy and global preferences for different routes of medicine administration, we can factor in how the new vaccines we develop might be received from the very beginning of the process, thus giving them the greatest chance of real-world success. 

The future of vaccination

My focus is needle-free, mucosal vaccinations, which are administered via the mouth, under the tongue and other mucosal surfaces.  

There are many benefits to mucosal vaccination. First, by being needle-free, people with needle-phobia can take them. But they also tend to be more effective than injected vaccines at creating a strong immune response on mucosal surfaces, because of the direct application and vaccine processing by the mucosal immune system. 

Mucosal surfaces are the portals through which pathogenic microbes enter our system. We therefore need strong mucosal immunity as a first line of defence to reduce the risk of transmission of infectious disease.  

Furthermore, mucosal vaccines allow us to more effectively target an affected site. Among other projects, I am working on a sublingual vaccine for Clostridium difficile, a bacterium that can cause diarrhoea and colitis after attaching in the large intestine.  

When you inject a vaccine it goes directly into the bloodstream, but it is not targeted. This leads to the required antibodies being present in the blood. Unfortunately, often only a small amount of these antibodies reach the mucosal surfaces, leading to a weaker immune response in these locations. 

Mucosal vaccines produce both systemic and local immune responses, giving immunity in the bloodstream, but also the mouth, nose, lungs, vagina, and crucially for this bacterium, the gut. By achieving mucosal immunity on the surface of the intestine, we can stop the attachment of the Clostridium difficile bacteria and prevent the infection from developing in the intestine.   

Mucosal vaccinations also offer several logistical benefits. Because oral, nasal and sublingual vaccines can be self-administered, they could be delivered by post to those who may struggle to attend vaccination centres.  

Injectable vaccines require a trained healthcare professional, a healthcare environment and a safe way to dispose of used needles and syringes. In addition, needle-stick injuries and unsafe injections are estimated to cause millions of infections each year. These requirements and challenges affect vaccine coverage and uptake, particularly in low- and middle-income countries. 

By removing the needle, we can avoid many of these issues.  

With my team, we are currently investigating the sublingual route for Group B Streptococcus (Strep) vaccination to prevent infection transmission from mother to baby during vaginal birth, as the sublingual route induces antibody responses in the vagina. 

There is potential for much broader use of mucosal vaccination. For example, the vaccines that were developed for COVID were good at stopping us from getting sick, or at least from getting seriously ill. But they were less effective at preventing transmission of infection. An effective mucosal vaccine would likely have had a much greater chance of preventing transmission because of the greater mucosal immunity it would generate. It was developed in injection form because of the immense time pressure and the manufacturers’ familiarity with needle-based vaccine development. In the event of a future pandemic, I hope there is more focus on developing and testing mucosal vaccination.   

However, introducing more mucosal vaccines will require targeted education campaigns to explain why they are being used, their efficacy and their benefits. 

Culture and preference

Between 2014 and 2018, I ran an international survey in collaboration with university pharmacy departments and others, in 20 countries all over the world. It was the first study of its kind to demonstrate a significant association between culture and the preference for different routes of medicine administration.  

After all, it only makes sense to develop mucosal, needle-free vaccines if we know whether people are willing to take them, and what adjustments we must make to suit cultural preferences.   

Unsurprisingly, we found that the oral route of medicine administration was the most preferred in all cultures. However, the percentage of participants selecting this as their preferred route varied, from 98% in Protestant Europe to 50% in African-Islamic cultures. Globally, injection was the second most preferred route, which contradicted both our assumptions and much reporting about the deterrent effect of the fear of needles on medicine taking. 

In fact, injections were perceived as the most efficacious method and to have the fastest onset of action while they were also deemed to be the most painful. Some researchers have theorised that the pain associated with injection may be perceived as a sign of a powerful medicine. Alternatively, being given an injection by a medical professional can give the sense that one has received the best possible medical care, compared with a treatment they can administer themselves.   

Survey respondents did not rank oral or other mucosal routes of delivery as highly as injections for perceived effectiveness. These findings inspired us to consider how we can create training programmes and interventions that improve understanding of vaccines, routes of immunisation and increase vaccine uptake.  

Vaccination champions

In 2020, I helped develop a training programme to equip UCL Pharmacy undergraduates with the knowledge and skills to address vaccine hesitancy and become ‘vaccination champions’.  

The programme enabled the students to promote vaccination in their multitude of identities – not only as future pharmacists and healthcare professionals, but also as family and community members, neighbours and friends.  

During the COVID pandemic, we adapted this training programme and delivered it via online workshops to Community Engagement Officers employed by local government. The goal was to increase their scientific knowledge about COVID vaccines and vaccination, and their confidence when engaging with vaccine-hesitant individuals. It enabled them to more effectively answer questions and provide information and solutions, dispelling myths and misinformation. 

This project inspired further work after the Community Engagement Officers reported that race and religion were frequently mentioned in vaccine conversations. It demonstrated the importance of a holistic approach to improve vaccine confidence and acceptance.   

Interfaith interventions

Having found some research papers that associated religiosity with lower COVID vaccine acceptance, we conducted a series of focus groups in 2023 to inform the development of interfaith interventions to address vaccine hesitancy. 

Previously, most faith-based research and interventions have been investigated in individual faiths. But with participants from different faith groups, ethnicities and backgrounds:

We have found that interfaith discussions, where multiple faith leaders can together emphasise the importance of vaccines, would be highly beneficial in fostering trust and supporting vaccine uptake.  

Direct engagement and dialogue with community organisations and faith leaders as well as the creation of ‘therapeutic alliances’ between the healthcare sector and religious communities also emerged as popular routes for improving vaccine confidence and tackling misconceptions. This means that increased vaccine uptake could occur where trusted community or faith leaders advocate for its benefits or have developed bespoke information to address people’s concerns. 

Now in the closing stages of this project, we will set out a series of recommendations as to how best to implement these interventions.  

The challenges ahead 

I believe the future of vaccination will involve a greater focus on mucosal immunisation in humans, more veterinary vaccinations in fish, poultry and livestock, and more combination vaccines to streamline an already busy immunisation schedule.  

The COVID pandemic brought vaccine research and hesitancy into the spotlight. While the rapid development of COVID vaccines was a triumph of science, the hesitancy surrounding them highlights the need for more interdisciplinary work and interventions.

We need further integration of social sciences into vaccine development to ensure that scientific advancements are matched by public understanding and acceptance.

The eradication of preventable diseases ultimately depends on public willingness.  

Sudaxshina Murdan is Professor of Pharmaceutical Sciences at the UCL School of Pharmacy.