The Hidden Supply Chain Risk in Vaccines: Why Sustainably Sourced Squalene Matters

Ingredient security is no longer a background consideration for vaccine formulators and manufacturers. It is now critical high-quality ingredients are sourced from proven partners, that can provide a secure and consistent supply to support the vaccines of tomorrow and equally be prepared to deliver a resilient supply through future pandemics.

There has been growing momentum to not just focus on the intricate parts of the vaccine development supply chain, but to go straight to the source of the ingredients. Where are they coming from? Is the source unlimited in supply, without having a negative impact on ecosystems and the environment? Squalene is a clear example of innovators asking questions at the right time.

Squalene is a well-established component in emulsion adjuvant systems; it plays an important role in vaccine formulation. Squalene is used to help strengthen the body’s response to the vaccine antigen, supporting protection against diseases like seasonal influenza and emerging pandemic flu strains. Beyond influenza, squalene containing adjuvant systems continue to be explored in clinical development across other disease areas.

Traditionally, squalene has been sourced from deep-sea shark liver, a practice that raises sustainability and ethical concerns. The latest amendment to CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) Appendix II includes all gulper sharks (Centrophoridae spp.), a family of species historically used for squalene because some have very large livers with high squalene concentrations. Regulation of responsibly sourced shark-derived squalene is tightening, with increased monitoring requirements expected to become effective during 2027. This regulatory change reflects the objective of protecting these species and helping ensure that international trade does not compromise their survival in the wild. Countries that do not adopt the Appendix II amendment would still need to comply with CITES requirements for export purposes. As a result, there is a high likelihood that this will place additional pressure on an already constrained supply chain, affecting both availability and pricing.

A broader conversation has begun. By switching from shark-derived squalene to Croda Pharma’s Sustainably Sourced Squalene, vaccine formulators and manufacturers can access a non-animal-derived, secure, consistent, and high-purity source. This fermentation-based source offers the flexibility to scale up rapidly in response to market demand. Fermentation-derived squalene is not subject to CITES regulation.

To explore this further, we spoke directly to our experts to share their perspectives on the future of Sustainably Sourced Squalene. From sustainable sourcing and manufacturing scale-up to quality assurance. Hear from Dr. Rasmus Münter (Lead Research Scientist), George Grimsey Jones (Sector Sustainability Specialist), Rebecca Murray (Operations Manager – Leek U.K.), Helen Albans (Regulatory Submissions Manager), Davina Nagington (Quality Control Manager, Leek U.K.).

Vaccine manufacturers can face different challenges with different sources of squalene. Traditional sources of squalene are the incumbent, but their insecurity of supply and ecological impacts are increasingly seen as unacceptable risks, particularly considering the long development and intended use cycles of vaccines. Newer sources of squalene provide a more secure long-term supply chain, while avoiding the ecological impacts and risks of shark-derived squalene. However, not all alternatives to shark-derived squalene are the same. Scalability is a vital issue for vaccine supply chains seeking to support an increasing number of vaccines while being prepared to respond to outbreaks and even pandemics. This is why new sources of squalene must be capable of scaling with secure supply, consistent quality, and minimal environmental impact. New sources of squalene are often plant derived, creating demand for land and agriculture. It’s therefore vital that the most efficient routes to squalene are used to minimise these demands and impacts. Harnessing synthetic biotechnology ensures efficient production of squalene from biobased carbon sources, minimising environmental impacts and demands for land and agriculture while transitioning away from shark derived material.

How does Sustainably Sourced Squalene compare to the well-established and proven shark-derived squalene?

Our Sustainably Sourced Squalene is molecularly identical to squalene from traditional shark sources. Alongside the benefits to security and sustainability of supply, our squalene is also produced to an even higher purity than traditional sources. While shark-derived sources are the well-established incumbent, the equivalence and increased purity of our squalene give Croda Pharma and our customers confidence in it.

Croda is committed to being climate, nature, and people positive, and Sustainably Sourced Squalene has clear alignment with all three. This is an ongoing journey. We also have various programs and embedded processes working to continuously improve the sustainability of our operations and supply chains.

How does Croda Pharma ensure continuity of supply during periods of high global demand?

Collaboration is key at Croda, and we maintain close relationships with our suppliers and our partner Amyris Inc.. Through utilising forecasting and order data, our operations teams can coordinate production planning to meet demands. This is further complimented by flexible production assets, meaning we have versatility in manufacturing scale. To support local supply, Croda operates on a global footprint with warehousing infrastructure across all regions. Croda’s Sustainably Sourced Squalene has also demonstrated excellent temperature stability, meaning it does not require refrigerated or frozen shipment. This provides a further opportunity for flexibility, with all this translating to Croda Pharma being a consistent and reliable source of supply.

What additional quality testing or controls are in place beyond standard pharmacopeia requirements?

The standard European Pharmacopoeia sets out a GC assay method which has known limitations and is not sufficient to demonstrate the high purity required for vaccine applications. We have developed our own GC methods, which include a purity method to demonstrate ≥99% purity, plus a separate method to quantify impurities present. We’ve proven alignment of the monograph and Croda methods, demonstrating that Croda Squalene exceeds the minimum purity requirements outlined in the monograph.

Why do you believe the technology and manufacturing process of Sustainably Sourced Squalene represent the future for squalene supply for vaccines?

The reasons for moving away from animal-derived squalene are clear. Ethical considerations and tightening regulations to preserve biodiversity in marine ecosystems make the transition to alternative sources increasingly compelling. At the same time, global health depends on access to secure, reliable sources that meet stringent regulatory requirements.

This aligns with Croda’s sustainability ambitions, including its Commitment to be Climate, Nature and People Positive by 2030. Developing a viable alternative to animal-derived squalene is a natural extension of that commitment and supports customers in addressing both sustainability and supply challenges.

Our Sustainably Sourced Squalene meets the key requirements of the vaccine industry, from product quality to global supply and distribution. Although it represents only one component in vaccine formulation, it plays an important role in supporting reliable access to life-saving vaccines. Even in the absence of a current legal or regulatory obligation, a transition to alternative sources strengthens resilience. What if supply was disrupted in the future, whether driven by a regulatory ban or depletion of shark populations?