A decade ago there was barely anything at Raheen. Today, on the edge of Limerick city, Regeneron runs what it calls the largest-scale bulk biologics production facility in Ireland. Since opening its European business office in Dublin in 2013 and choosing Limerick for its first manufacturing plant outside the United States, the New York biotech has kept adding capacity, staff and specialist roles at Raheen, with engineering and quality hiring still active through 2025 and into 2026.
From start-up to Ireland's largest biologics plant
Regeneron chose Limerick in 2013 for its first Industrial Operations and Product Supply, or IOPS, site outside the United States, with manufacturing beginning at the Raheen facility the following year. By the end of 2016 the company had already beaten its own hiring projections, welcoming its 350th Irish employee, and had begun building new quality control laboratories and a process sciences building on site.
That growth accelerated further in 2020, when Regeneron announced more than 400 additional jobs at Raheen, bringing total headcount at the campus above 1,400, as the site ramped up capacity to help free up the company's New York facilities during the pandemic. IDA Ireland's own case study on the company describes total investment at the Limerick site as exceeding $1 billion, with Regeneron describing Raheen as the largest bulk biologics production facility in the country.
That scale-up did not stop once the immediate pandemic pressure eased. Regeneron has kept adding buildings, laboratories and specialist functions at Raheen through the years since, gradually shifting the site from a single production facility into a fuller campus that also handles process sciences, quality control and its own engineering and project delivery teams rather than relying solely on manufacturing headcount.
A hub for serious disease treatments
The Raheen campus manufactures biologics used in Regeneron's medicines for serious diseases including cancer, asthma and infectious disease. Regulatory approvals secured in 2017 from both the US Food and Drug Administration and the European Medicines Agency allowed the site to manufacture medicines for distribution in both the US and EU markets, giving Limerick a genuinely global manufacturing role within Regeneron's network rather than a purely regional one.
Company materials describe Regeneron's Irish operation as combining the culture of 'a start-up mentality' with the resources of an established biotech employer, reflecting how quickly the Limerick site has scaled since 2014 while still adding new capability.
Having FDA and EMA approval on the same Limerick lines means product made at Raheen can be shipped into both the US and European markets without needing a second, geographically separate manufacturing line, a genuine efficiency for a company operating at Regeneron's global scale, and one that underpins its wider IOPS network's ability to treat a broad range of serious conditions.
Regeneron's global product range manufactured through that IOPS network includes treatments developed with its long-running collaboration partner Sanofi, as well as therapies from Regeneron's own pipeline, meaning Raheen's output supports medicines sold under multiple company banners internationally rather than a single, narrow product line, a further reason the site has continued to justify fresh investment even as the broader biotech funding environment has fluctuated in recent years.
Continued hiring through 2025 and 2026
Recruitment at Raheen has continued well beyond the initial post-pandemic hiring push. Through 2025 and into 2026, Regeneron has been actively hiring for specialist roles at the Limerick site, including engineering, manufacturing scheduling and quality assurance positions, according to the company's own careers listings.
Roles advertised include a Senior Project Engineer responsible for designing, specifying and commissioning new and renovated biopharmaceutical process equipment, a Manufacturing Scheduling Specialist supporting production planning across the site, and a Principal QA Specialist overseeing quality systems, change control and regulatory compliance. That spread, from hands-on engineering to senior quality leadership, points to a site that is still maturing and adding capability rather than simply maintaining existing production lines.
Further postings through the middle of 2026 add to the picture: a Project Engineer role advertised in August 2026 covers designing and specifying cGMP process equipment, piping and controls, and supporting validation and investigations into process anomalies, work squarely focused on keeping an already-running biologics plant current rather than building a new one from scratch [Regeneron Careers](https://regeneron.wd1.myworkdayjobs.com/en-US/Careers/job/Limerick/Project-Engineer_R49585). A Senior QA Specialist post advertised around the same time focuses on quality oversight for technology transfer projects and the introduction of new manufacturing technologies, including digital tools such as manufacturing execution systems and electronic batch records, suggesting Raheen is also modernising its existing production lines digitally as it grows.
Entry-level manufacturing operations roles have continued to be advertised too, working shift patterns in fully gowned cleanroom environments on both clinical and commercial production, showing that Regeneron's Limerick hiring spans the full range from production floor staff through to senior engineering and quality leadership, not just specialist positions.
That breadth of open roles, still being advertised well into the second half of 2026, suggests Regeneron sees Raheen as a site with room to keep growing rather than one that has already reached its natural ceiling, a pattern consistent with a decade of steady, incremental expansion at the campus since it first opened.
Why Limerick keeps winning Regeneron's investment
Regeneron highlights the Mid-West region's advantages in its own recruitment material, pointing to the University of Limerick's education pipeline, the city's motorway links to Dublin, Belfast and Galway, and a comparatively affordable cost of living for staff relocating to the site.
Those local factors, combined with a workforce that has already delivered a decade of steady scale-up, help explain why Limerick has remained Regeneron's chosen European manufacturing base even as the company has grown into a global biotech with more than a dozen approved medicines and thousands of employees worldwide.
The University of Limerick's engineering and science graduate pipeline is a specific draw for a biologics site that needs a steady supply of process engineers, quality specialists and scientists close to home, reducing Regeneron's reliance on relocating staff from overseas as the campus continues to grow.
Regeneron's continued presence in Limerick also feeds back into the wider Mid-West economy, supporting local suppliers, contractors and graduate recruitment pipelines at a scale that few single employers in the region can match, reinforcing why the company has chosen to keep expanding at Raheen rather than looking elsewhere in Ireland or Europe for additional manufacturing capacity.
Continued building activity at Raheen
Planning records show building work at Raheen continuing into 2025 and 2026. Regeneron applied to Limerick City and County Council in mid-2025 for modifications to a temporary contractors' compound and heavy goods vehicle access point tied to its ongoing site development, an application that was later refused on appeal by An Coimisiún Pleanála in January 2026, a reminder of the everyday planning and construction logistics that come with keeping a large, still-growing manufacturing campus running smoothly.
Alongside its permanent workforce, Regeneron's Limerick operation has at various points supported several hundred contractor and construction personnel on site, work that has continued in phases since the original 2014 build, reflecting how a site of Raheen's scale keeps adding, renovating and requalifying manufacturing space even once its main buildings are up and running.
That steady drumbeat of site works, alongside the specialist recruitment described above, points to a campus Regeneron continues to actively develop rather than one that reached a fixed, final size once its headline $1 billion investment was announced.
The Bottom Line
Regeneron's Raheen campus has grown from a handful of Dublin-based hires in 2013 into what Regeneron describes as the largest bulk biologics production site in Ireland, backed by more than $1 billion of investment, and the hiring has not let up. Ongoing recruitment for engineering, scheduling and quality roles through 2025 and 2026 shows a site Regeneron continues to invest in and expand, cementing Limerick's place in the company's global manufacturing network.
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