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Vaccine clinical trials

We understand the customer burden to find, engage and recruit the right volunteers into vaccine studies. Trials demand agility to adapt to changing study environments—from shifting disease hotspots to evolving diversity requirements. We also know that the right clinical site network is critical to manage these large, complex trials, handle volume spikes and keep studies on schedule.

We have 25 years of experience profiling volunteers and patients and randomizing them into studies, giving us key insights into pre-pooling volunteers prior to start-up and managing surge capacity. 

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More than 10 COVID-19 Phase I-III studies, with leading vaccines clients and 18,000 volunteers randomized

Vaccine clinical trial volunteer enrollment and global site network

Tough challenges demand innovative solutions. At the heart of our vaccine recruitment solution is our geo-targeted centralized recruiting platform that finds and recruits the right volunteer populations on a massive scale. We go directly to the volunteer with the message and medium best targeted for that individual.

Then we offer a global clinical site network of more than 80 ready-to-deploy, vaccine-enabled sites purpose-built for large volume studies and delivering global, consistent operations — all with investigators seasoned in managing vaccine studies.

AES Experience in Vaccines

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Supported vaccine trials from first-in-human and Phase I-III

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Randomized volunteers in 30 major vaccine areas


We’ve successfully supported vaccine protocols for a range of infectious and emerging diseases like COVID-19, Ebola, H5N9, Anthrax, and Zika during times of public health crisis, as well as influenza and RSV.

Example indication details# Trials# of Randomized Volunteers
RSV164.4K +

Advanced solutions are needed to overcome difficult enrollment challenges

This experience doesn’t just give us unmatched expertise – it gives us the data we need to create recruitment plans that we know will generate results for your study, and the confidence to back up our results with performance-based pricing. We also glean the insights to identify more accurately the volunteers most likely to enroll in your study; more effectively speak to their needs, motivations and preferences; and more efficiently communicate this message via the channels that they prefer to engage with throughout their journey.

Learn about our COVID-19 Vaccine clinical trial support

Targeted community outreach strategy in specific communities

We have proven methodology to engage diverse populations. Many populations are often underrepresented in access to medical treatment and clinical research, and participating in a clinical trial is a burden that can be particularly acute. That’s why our messaging and creative is specifically tailored to take into account the perceptions and needs of each diverse population, including their attitudes toward clinical research and their motivations and barriers to become involved.

Our epidemiologically driven recruitment strategy means that we focus more resources in the optimal geographies. From there, we leverage our proprietary database of over 21.5 million diverse households and create models with data partners to target the relevant geographic area and interests. 

In addition to traditional outreach via social media, direct mail, etc., we access volunteers through familiar, local and well-trusted connections within their community (e.g., outreach to community- and faith-based organizations), as well as through our global network of providers and healthcare systems. We then offer flexible scheduling, virtual first office visits and minority investigators/staff at the site to improve the volunteer experience.

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average volunteer retention rate

Our site network includes sites experienced in running large studies 

AES sites offer a full complement of staff and physical space to accommodate large volumes of subjects efficiently and with high quality. Our large-scale screening and processing capabilities help manage volume spikes to keep trials on schedule. 

For COVID-19 trials, for example, volunteers are only needed on site for an average of 60-90 minutes for visits. This efficiency not only makes for a better volunteer experience, but it means we can process more volunteers. Over 30,000 referrals visit AES research sites each month to be evaluated for studies, and each site is capable of screening over 250 people a day.

AES offers a superior vaccines trials solution

Whether you select your own sites or AES dedicated Clincial Research Network that offer vaccine expertise, our solutions combine the ideal competencies to provide greater certainty of enrolling vaccine clinical trial volunteers and meeting your timeline.

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We’ve supported more than 25 government funded programs over the past five years