Sanofi Sues Pfizer and Moderna Over COVID Vaccine Patent Rights

Sanofi has sued Pfizer and Moderna in federal court, accusing both companies’ COVID-19 vaccines of infringing patents that its Translate Bio unit holds on messenger RNA (mRNA) delivery technology. The French drugmaker filed two separate complaints Tuesday in New Jersey, and Reuters first reported the filings. Sanofi wants royalties, not a ban on either vaccine.

It is the latest entry in an mRNA patent fight that began in 2022 and has already produced a $2.25 billion settlement, a string of invalidated patents and at least one courtroom loss for each side. The new case gives an early look at how this one might go.

Two Lawsuits Built on the Same Patent Family

Sanofi filed both complaints Tuesday, July 14, in the U.S. District Court for the District of New Jersey, a venue already handling several other mRNA patent fights. One targets Moderna, the other Pfizer, and both draw on patents assigned to Translate Bio, the Massachusetts biotech Sanofi acquired for $3.2 billion in 2021.

Two of the underlying patents, numbered 10,238,754 and 10,413,618 in court filings, cover lipid nanoparticle compositions and mRNA delivery methods. Lipid nanoparticles, or LNPs, are fatty shells that protect fragile mRNA strands long enough to reach human cells, where the genetic instructions trigger an immune response. Moderna and Pfizer/BioNTech were the first mRNA-LNP vaccines to enter clinical trials during the pandemic.

Sanofi is not asking a judge to pull either vaccine off pharmacy shelves. The company wants a jury trial and financial damages instead. It said in a statement that it was “seeking fair compensation for use of its patented technology.” The complaints also target how the vaccines are given, arguing that healthcare workers use Translate Bio’s patented methods every time they administer a shot.

Why Did Sanofi Wait Until Now to Sue?

Sanofi bought Translate Bio for $3.2 billion in 2021, hoping to build its own mRNA COVID-19 vaccine. That vaccine never reached pharmacies. Five years later, the same lipid nanoparticle patents are generating lawsuits instead of doses, as Sanofi tries to collect from rivals whose shots succeeded where its own program stalled.

The early signs looked good. A Phase 1/2 study posted positive interim results in September 2021, and Sanofi talked up plans to push the platform toward a modified flu vaccine. But the COVID-19 candidate never won approval, and Sanofi’s pandemic vaccine business instead ran through a protein-based shot developed with GSK.

The Translate Bio deal did not go to waste. Sanofi is now combining its lipid nanoparticle and mRNA capabilities with other acquired technology to build an in vivo CAR-T platform, a cell therapy delivered by injection rather than grown in a lab. The patent office keeps handing Sanofi fresh ammunition too: intellectual-property analytics firm Knowmade found Sanofi led the field with four new lipid nanoparticle patents in a single quarter, more than any other company tracked.

Markets Shrug While Analysts Crunch the Numbers

Investors did not panic. Sanofi’s U.S.-listed shares rose about 1.1% after the filings. Moderna gained roughly 1.2%. Pfizer’s vaccine partner BioNTech added about 1.7%. Pfizer itself climbed 2.35% to $24.82 the day after the suits were filed.

The muted reaction reflects how small Comirnaty has become. Pfizer’s COVID-19 vaccine brought in just $232 million in the first quarter of 2026, down 59%, as fewer contracted deliveries overseas and a narrower U.S. vaccination recommendation cut demand. That is a fraction of the $95.8 billion Comirnaty has generated for Pfizer since 2021.

One rough sensitivity check: at Pfizer’s Wednesday market value of $142.2 billion, a damages award equal to just 1% of that historical revenue pool would run to roughly $958 million, about 0.7% of the company’s equity value. That is a back-of-envelope comparison, not a damages estimate. Actual liability would hinge on whether the patents hold up, whether infringement is proven, what dates apply, and what slice of sales a jury attributes to the disputed technology.

Pfizer’s own filings note that damages can triple when a court finds infringement was willful. The company still has plenty of non-COVID business to lean on. Revenue excluding Comirnaty and Paxlovid grew 7% operationally last quarter, and Pfizer kept its 2026 guidance of $59.5 billion to $62.5 billion in revenue. Pfizer had not responded to a request for comment on the new suit as of Wednesday.

A Billion-Dollar Playbook Is Already Written

Sanofi is not the first company betting that old mRNA research can still generate new cash. The pattern is well established, and it has already produced billions in payouts.

Moderna agreed in March to pay Arbutus Biopharma and Genevant Sciences $950 million upfront, plus as much as $1.3 billion more, for a maximum of $2.25 billion, resolving a separate lipid nanoparticle dispute. As part of the deal, Moderna also agreed to let the district court enter judgment affirming four Arbutus patents as valid rather than keep fighting the validity question.

Jefferies analyst Andrew Tsai called the payment small next to Moderna’s roughly $48 billion in past vaccine sales, writing that the deal “removes the worst-case scenario” of double-digit royalty rates.

Pfizer and BioNTech settled a separate dispute in 2025, paying GSK and CureVac $320 million upfront. Moderna and BioNTech have also each cut checks to the National Institutes of Health (NIH), reportedly $400 million and $791.5 million respectively, agreements said to include small ongoing royalties on future sales.

The Scorecard Cuts Both Ways

Patent counts make a weak proxy for who actually wins. The record so far is mixed, patent by patent, country by country.

• Two patents down: The U.S. Patent Office ruled two of Moderna’s mRNA vaccine patents unpatentable in March 2025, a win for Pfizer and BioNTech.
• One patent up: A British appeals court upheld a finding that a separate Moderna patent was valid and infringed by Pfizer and BioNTech.
• A German loss, too: A court in Germany separately ruled that Pfizer and BioNTech infringed one of Moderna’s European patents, with damages still to be determined.
• One case dismissed outright: Alnylam Pharmaceuticals’ infringement claim against Pfizer and BioNTech ended in a judgment of non-infringement.

The split outcomes turn on specific claim language, not a blanket verdict on mRNA technology. Even the U.S. Patent Office case that ruled two Moderna vaccine patents unpatentable left a third, unchallenged Moderna patent claim alive in Massachusetts federal court, and Moderna can still appeal the invalidation.

Sanofi Joins a Long Line of Claimants

Sanofi is also not the only company lining up outside Pfizer and Moderna’s door.

• Bayer sued Pfizer, BioNTech and Moderna in January, alleging the companies used its patented method for reducing polyadenylation signals in mRNA payloads to improve protein output.
• CureVac has an active federal claim accusing Moderna’s Spikevax of copying its proprietary methods for stabilizing mRNA.
• GSK sued both Moderna and Pfizer/BioNTech starting in 2024, ahead of collecting its share of the $320 million CureVac settlement in 2025.
• Northwestern University sued Moderna for infringement in 2024.
• Arbutus Biopharma and Genevant Sciences, fresh off their settlement with Moderna, filed new infringement suits in Canada and the UPC against Pfizer and BioNTech within the past two weeks.

The through-line is simple. None of these companies built a blockbuster vaccine of their own. All of them hold patents that read on the delivery or stabilization technology every mRNA shot depends on.

The Docket Still Lacks a Trial Date or a Dollar Figure

What We Know:

• Sanofi filed two complaints Tuesday in the U.S. District Court for the District of New Jersey.
• One accuses Moderna’s Spikevax, mNexspike and mResvia of infringing 10 patents; the other accuses Pfizer’s Comirnaty of infringing eight of the same patents.
• Sanofi is seeking a jury trial and monetary damages, not an injunction against either vaccine.

What’s Unconfirmed:

• Neither complaint specifies a dollar figure sought in damages.
• No trial date has been set in either case.
• Whether Sanofi’s patents survive a validity challenge, the same test that struck down two of Moderna’s patents last year.

Pfizer already faced five other claimant groups in Comirnaty patent actions before Sanofi’s complaint arrived, spanning courts in the United States and Europe. Sanofi’s case now joins that queue, behind litigants who have waited years for a ruling or a settlement check.

Comirnaty has produced $95.8 billion in revenue since 2021, a figure that dwarfs the $232 million it brought in last quarter alone, and it is that older, larger number a New Jersey federal court will now have to weigh.