Sanofi is running short of two medicines that people with Pompe disease rely on to stay well, and the shortage is already forcing some patients to postpone infusions or accept reduced doses. The drugs, Myozyme, an older standard of care, and Nexviazyme, a newer treatment, are enzyme replacement therapies for a rare, progressive, and sometimes fatal genetic disorder. According to STAT's Pharmalot, the shortage traces to a bottleneck and quality-control problems at a single plant in Waterford, Ireland, and it surfaced shortly after the Food and Drug Administration warned the company about manufacturing issues at that very facility.
For the families living through this, it is frightening in a direct and personal way. But the episode also exposes a fragility that reaches well beyond one company or one plant, and that is worth understanding, because it is built into the way medicines for rare diseases exist at all.
What Pompe patients depend on
Pompe disease is a rare genetic disorder in which the body lacks enough of an enzyme needed to break down a stored sugar, glycogen, which then accumulates in muscle and progressively weakens it, including the muscles used for breathing and, in the most severe cases, the heart. The severe infantile form can be fatal early in life without treatment. There is no cure. What holds the disease at bay is regular infusion of a replacement enzyme, which is exactly what Myozyme and Nexviazyme provide.
That is why this shortage is not the kind of inconvenience a shortage of a common medicine might be. These infusions are not optional or elective; they are the thing standing between a patient and the advance of the disease. A postponed infusion or a reduced dose is not a scheduling problem. It is a period during which the condition may regain ground that treatment had been holding. The stakes, stated plainly and without exaggeration, are the patients' continued stability.
A single point of failure
The most striking detail in the account is how narrow the choke point is. The shortage traces not merely to one company but to one facility, and within that facility to one step: what the industry calls batch release, the final quality certification in which a manufactured batch of medicine is formally verified to meet safety and potency standards and cleared for distribution. Because Pompe disease is rare, there is a single manufacturer of these therapies, and the entire global supply passes through this one plant and this one step. There is no second supplier, no backup site, no redundancy anywhere in the chain.
So when that facility hits a bottleneck or a quality problem, as it has, in the wake of an FDA warning, the drug that keeps patients stable abruptly becomes scarce, and there is nothing to fall back on. This is the textbook definition of a single point of failure: a system in which one component, if it falters, brings down the whole. Most critical systems are engineered specifically to avoid it. The supply of these particular medicines was not, and could not easily be.
Even the last step can halt everything
It is worth pausing on what batch release actually is, because it shows how a supply chain can break at a stage that sounds purely clerical. A drug can be completely manufactured, physically finished and sitting in a facility, and still not reach a single patient until it clears batch release, the certification confirming it meets the required standards for safety and strength. A bottleneck or a quality failure at that final step can therefore create a genuine shortage even when the product exists, because it cannot lawfully be distributed until it is certified.
A supply chain is a sequence of links, and it is only ever as strong as its weakest one. A failure at any link, including the last, stops the entire flow. For these drugs, several of those links, manufacturing, quality control, and final certification, run through the same facility, so trouble anywhere inside it can sever the chain. And it is worth being fair about that final link: batch release is not bureaucratic obstruction. It is the safety check that keeps a substandard batch of a potent biologic from being infused into a vulnerable patient. You would want it in place even knowing it is a choke point, which is precisely what makes this kind of fragility so hard to engineer away.
Rare-disease drugs are fragile by design
None of this is unique to Pompe disease or to Sanofi. It is a structural feature of medicine for rare conditions, and it follows almost inevitably from the economics of rarity. A small patient population can support only one manufacturer, or a few, often running a single production line, with little or no redundancy. The complexity of the products and the smallness of the market mean there are no generic competitors waiting to fill a gap. And the specialized, thin supply chains that result are not built for resilience, because resilience, a second plant, a backup certifier, a stockpile, is expensive and difficult to justify commercially for so few patients.
The consequence is that people with rare diseases depend on supply chains that are inherently more fragile than those for common drugs, which typically have many manufacturers, generic alternatives, and redundancy at every stage. This fragility is not the failing of any single company. It is the flip side of the drug existing in the first place. The very rarity that makes a treatment a genuine medical triumph, a therapy developed and produced for a population too small to be a mass market, is what leaves its supply resting on so few, and sometimes on one, points of production.
The cruel mismatch
And here is the hardest part of the picture. The stakes are highest exactly where the supply is most fragile. These are life-sustaining medicines with no substitute, taken by patients who deteriorate without them, which means the people most dependent on an absolutely uninterrupted supply are served by the most fragile supply chain there is. The mismatch is not anyone's intention, but it is real, and it is a kind of structural cruelty. A manufacturing hiccup that would be a minor and quickly forgotten story for a widely made drug becomes, for a rare-disease drug, an emergency measured in patients' health.
What is fair to say about Sanofi
This should not be read as a hunt for a villain, and a fair accounting matters. In the immediate term, Sanofi appears to be doing the right thing by alerting patient groups and physicians early, in both the U.S. and Europe, which lets clinicians plan rather than be blindsided, prioritizing the most vulnerable patients and managing dosing through the shortage. Manufacturing these enzyme therapies is genuinely difficult; they are complex biologics held to exacting standards, and a quality problem, while serious and worth scrutiny, is not by itself proof of negligence. And the absence of a backup facility reflects the economics of rarity far more than any single corporate decision, since building redundancy for so small a market is hard to justify on commercial terms, which is exactly the structural gap at issue.
The vulnerability is real and deserves to be named clearly. But laying it entirely at the feet of one company would misplace the cause, which lies in a system whose incentives do not naturally produce resilience for the drugs where an interruption hurts the most.
For the families living through this shortage, the need is immediate and uncomplicated: a restored, reliable supply of the medicine that holds their disease in check, which now depends on Sanofi repairing its plant and regulators clearing it to resume. The larger point the episode makes is harder to resolve. The same rarity that makes a Pompe treatment a triumph, a drug that exists at all for so few people, is what makes its supply so precarious: one company, one plant, one step, and no backup, because no market rewards building one. The deeper question it raises is whether a system capable of producing near-miraculous drugs for rare diseases can also be built to deliver them dependably, because a life-sustaining medicine that patients cannot count on receiving is, in the end, only half a cure. For now they wait, and the honest hope is for a short wait and a quick fix. But the fragility that made this wait possible will still be there when the shortage ends.
Primary sources
- STAT Pharmalot, in reporting by Ed Silverman, for Sanofi's shortages of Myozyme and Nexviazyme for Pompe disease, the resulting postponed infusions and reduced dosages alarming patient groups, the emergence of the problem shortly after the FDA warned the company about manufacturing issues at its Waterford, Ireland, facility, the description of the cause as a bottleneck in the final manufacturing phase together with quality-control issues, and the explanation that the Waterford site handles batch release, the final quality-assurance and regulatory step that certifies a batch as meeting safety and potency requirements before it can be distributed.
- European Medicines Agency product information, as referenced in that reporting, regarding the site's batch-release role.
- General, well-established background on Pompe disease as a rare lysosomal storage disorder caused by deficiency of the enzyme acid alpha-glucosidase, its progressive muscle, respiratory, and cardiac effects, the fatality of untreated infantile-onset disease, the role of enzyme replacement therapy as the mainstay of treatment, and the economics of rare-disease drug supply chains.