Dengue outbreaks are rising. A promising antiviral was deserted by its maker.

[ad_1] There’s a cause dengue infections are additionally known as “breakbone fever.”

Together with a gentle fever, signs of the mosquito-borne sickness embrace bone-deep, aching ache within the joints and behind the eyes. In extreme circumstances, blood vessels start to leak. And within the worst circumstances, that may result in organ failure.

Greater than 14 million folks contracted dengue last year , and the actual quantity is probably going a number of instances larger. Whereas it stays commonest in South Asia and Latin America, it’s not only a tropical illness. Warming temperatures are pushing dengue into southern Europe and the US. Final 12 months, Texas noticed its highest case count in two decades , together with regionally acquired infections, which means the virus is now circulating right here, not simply arriving with vacationers.

Dengue has no therapy. Docs can handle the ache and hold you hydrated, however there’s nothing that truly fights the virus. However, a brand new capsule known as mosnodenvir simply proved it might cease the virus, the primary time any drug has been proven to have effectiveness in opposition to dengue. Nonetheless, Johnson & Johnson, the corporate behind mosnodenvir, already walked away from growing it, becoming a member of a protracted line of drug makers chasing higher cash in most cancers and weight problems medicine. The illness is now spreading to new elements of the world. The drug is caught in limbo, and the hole between what we want and what the market will fund retains rising. The general public well being instruments we have now — the dengue vaccines , mattress nets, fogging campaigns, public consciousness to empty standing water — are all aimed toward holding mosquitos at bay and stopping infections within the first place. There’s nothing for after: no antivirals — nothing like Paxlovid for Covid, or Tamiflu for the flu, or artemisinin for malaria. When you’re sick, the technique is simply supportive care and hope.

Earlier this month, although, that modified.

A brand new antiviral capsule for dengue known as mosnodenvir confirmed promising leads to early phase 2 trials . In a research the place volunteers have been intentionally uncovered to dengue, roughly half of those that obtained the very best dose by no means received sick in any respect. For a subject that has struggled for many years to seek out an efficient antiviral, it’s the clearest proof but {that a} drug can forestall dengue — and researchers consider the identical capsule may ultimately deal with people who find themselves already contaminated.

However, even earlier than the outcomes have been printed, Johnson & Johnson, the American pharmaceutical large that developed mosnodenvir, had already deserted any efforts to carry the drug to market.

Final 12 months J&J introduced it could wind down its dengue antiviral work, with a “strategic reprioritization” of its analysis towards non-communicable illnesses like most cancers and weight problems. What this implies is that one of the crucial promising dengue medicine ever examined is now with no pharma sponsor, ready for another person to hold it ahead.

André Siqueira, who heads the dengue program on the Medicine for Uncared for Ailments Initiative (DNDi), stated mosnodenvir is “very, very promising” and stated he needs to see it pushed into additional trials “as rapidly as attainable.”

However why — if the drug reveals a lot promise — would its maker stroll away?

J&J’s exit isn’t an outlier; it’s a part of a broader retreat from infectious illness analysis throughout the pharmaceutical trade, as firms shift towards medicine for wealthier markets: most cancers, weight problems, autoimmune problems.

Dengue already kills thousands every 12 months, and it’s getting worse. By 2080, climate models suggest , almost 60 % of the world’s inhabitants may very well be dwelling in areas the place dengue spreads.

And, on this new world, watching the primary antiviral capsule that works in opposition to dengue get deserted — whereas the illness spreads to new continents — reveals the hole between the medicine we want and the medicine the market will ship.

<img alt="A worker fumigates an alleyway in a densely populated neighborhood to kill mosquitoes" data-chromatic="ignore" loading="lazy" decoding="async" data-nimg="fill" class="mvmjsc0" style="position:absolute;height:100%;width:100%;left:0;top:0;right:0;bottom:0;color:transparent;background-size:cover;background-position:50% 50%;background-repeat:no-repeat;background-image:url("data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' %3E%3Cfilter id='b' color-interpolation-filters='sRGB'%3E%3CfeGaussianBlur stdDeviation='20'/%3E%3CfeColorMatrix values='1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 100 -1' result='s'/%3E%3CfeFlood x='0' y='0' width='100%25' height='100%25'/%3E%3CfeComposite operator='out' in='s'/%3E%3CfeComposite in2='SourceGraphic'/%3E%3CfeGaussianBlur stdDeviation='20'/%3E%3C/filter%3E%3Cimage width='100%25' height='100%25' x='0' y='0' preserveAspectRatio='none' style='filter: url(%23b);' href='data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mN8+R8AAtcB6oaHtZcAAAAASUVORK5CYII='/%3E%3C/svg%3E")" sizes="(max-width: 639px) 100vw, (max-width: 1023px) 50vw, 700px" srcset="https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=256 256w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=376 376w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=384 384w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=415 415w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=480 480w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=540 540w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=640 640w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=750 750w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=828 828w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=1080 1080w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=1200 1200w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=1440 1440w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=1920 1920w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=2048 2048w, https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=2400 2400w" src="https://platform.vox.com/wp-content/uploads/sites/2/2025/12/GettyImages-2184227989.jpg?quality=90&strip=all&crop=0%2C0%2C100%2C100&w=2400"/> A employee fumigates an alleyway in a densely populated neighborhood to kill mosquitoes within the capital metropolis of Dhaka, Bangladesh. Fumigation is without doubt one of the instruments public well being employees have to stop dengue an infection. MD Abu Sufian Jewel/NurPhoto by way of Getty Photographs

What the capsule truly proved

To check whether or not mosnodenvir truly works, researchers did one thing unusual: They intentionally contaminated folks with dengue.

Over the previous three years, 31 volunteers in Baltimore and Vermont, in what’s called a challenge trial , agreed to take a capsule for a number of days after which get injected with a weakened dengue virus. It’s a quicker technique to get solutions than ready for folks to get sick naturally, however it requires volunteers prepared to join a managed case of dengue.

Amongst individuals who received the very best dose of mosnodenvir, 6 out of 10 by no means developed an an infection in any respect. The opposite 4 had a lot decrease ranges of virus of their blood and milder signs than the placebo group, the place everybody received sick. At decrease doses, the drug delayed an infection however didn’t forestall it — a transparent sign that the upper dose was doing one thing actual.

“It’s one of the crucial lovely dose-response outcomes I’ve seen,” Anna Durbin, the Johns Hopkins researcher who led the research, told Science last month .

Then, there’s the sector knowledge. In 2023, J&J launched a trial throughout greater than 30 websites in South America and Asia to check whether or not the drug may defend folks in the identical family who're at excessive threat of getting bitten by the identical mosquitoes. Amongst 265 individuals who obtained the very best dose, not a single particular person developed symptomatic dengue. Within the placebo group, 60 % did. (This knowledge hasn’t been formally peer-reviewed but, however it’s posted publicly .)

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For Neelika Malavige, a distinguished dengue researcher on the College of Sri Jayewardenepura in Sri Lanka, the importance goes past the numbers. “It’s an enormous scientific breakthrough simply doing the research,” she stated, referring to the design of the problem trial itself, which had by no means been completed for a dengue antiviral earlier than. For a illness with no authorised therapy, that is as near proof of idea because it will get.

“The dengue neighborhood could also be nearer than ever to a long-awaited therapy,” Xuping Xie of the College of Texas Medical Department wrote in a commentary accompanying the paper.

However, there are some caveats

The trial proved that mosnodenvir can forestall an infection, a primary for any dengue drug. However prevention isn’t what dengue docs want most. What they want is a therapy, one thing to provide sufferers who're already sick to maintain them from getting worse.

That’s what makes an antiviral so helpful. Prevention methods have a ceiling; you may cut back mosquito populations, however you may’t get rid of them, and warming temperatures hold pushing them into new territory. A drug that works after publicity can be the primary software that doesn’t rely on stopping the mosquito first.

The hope is that the identical drug may do each. Mosnodenvir works by blocking the virus from replicating, and, in principle, that ought to assist whether or not you are taking it earlier than you’re contaminated or shortly after. The query is timing.

That’s the place dengue will get tough. In contrast to malaria, the place the parasite lingers, and you may kill it with medicine, the dengue virus strikes by the physique notoriously quick. By the point a affected person feels sick sufficient to see a physician — often a number of days into the fever — the virus is usually already on its manner out. The brutal signs that observe, the blood vessel leakage and organ harm, are pushed largely by the physique’s personal immune response, not the virus itself.

As a world well being reporter, this story felt grimly acquainted. The issues we take note of get solved, and so-called uncared for tropical illnesses have turn out to be one thing that simply occurs elsewhere. It’s the rationale why tuberculosis continues to be the deadliest infectious illness and why it took 35 years to develop the primary malaria vaccine.

This line from a 2004 article captures this fairly nicely: “In all probability the worst factor that ever occurred to malaria in poor nations was its eradication in wealthy ones.”

I grew up in Mumbai, the place dengue was an everyday incidence each monsoon season. However the illness isn’t staying there anymore. It’s spreading — into southern Europe, into the US — and the query of who develops medicine for it's not another person’s drawback.

For this reason antivirals have been so arduous to develop for dengue. The window to intervene may be slim, and for a lot of sufferers, it’s already closing by the point they present up.

The scientists who developed mosnodenvir consider it may work as a therapy. “If you happen to cut back the quantity of replicating virus, additionally, you will cut back the chance that the affected person evolves in direction of extreme illness,” stated Johan Neyts, a virologist at KU Leuven whose lab co-discovered the drug. The logic is in keeping with how antivirals for, say Covid, work, however this speculation hasn’t been examined in people. Therapy trials have been deliberate in Singapore, however the Covid pandemic made them not possible. By the point restrictions lifted, J&J had already determined to exit.

The dream, Malavige stated, is straightforward, “You go to the physician, get your self examined, the take a look at is constructive, you’re given an antiviral, and that’s the top of the story.” The query is whether or not sufferers can get there early sufficient — and whether or not mosnodenvir can work.

There’s additionally the query of resistance. Within the human problem trial, genetic mutations emerged within the virus amongst almost all of the individuals who took mosnodenvir — mutations that might, in principle, make the drug much less efficient over time. And a few dengue strains already circulating in nature appear to be harder to treat with the sort of drug.

It is a actual limitation. Mosnodenvir alone in all probability isn’t a long-term resolution, as a result of, ultimately, the virus may adapt. However that drawback is a well-recognized one for drug makers. HIV and malaria each developed resistance to early medicine, and the reply was mixture remedy: a number of medicine that assault the virus in several methods, making it far tougher to flee all of them without delay.

For that technique to work with dengue, although, we want extra medicine to mix. Mosnodenvir is probably not the entire puzzle, however it may very well be the primary piece. “If folks stopped on the first signal of seeing hassle,” Malavige stated, “then the world is not going to progress.”

May Mosnodenvir…get adopted?

Johnson & Johnson’s exit follows a well-worn path for giant pharma.

Over the previous 20 years, Bristol Myers Squibb , Novartis , AstraZeneca , and different main drugmakers have all scaled again or deserted infectious illness analysis, judging that these medicine merely couldn’t compete with most cancers and weight problems blockbusters. A recent op-ed in the Financial Times known as it a “textbook market failure.” The general public well being influence is huge, however the monetary returns for addressing them aren’t.

After J&J’s exit, possession of mosnodenvir is being transferred again to KU Leuven, the Belgian college the place the drug was first found earlier than J&J licensed it for improvement. “We'll do all we are able to to be sure that mosnodenvir is additional developed in scientific trials as quickly as attainable,” stated Patrick Chaltin, who directs the college’s drug discovery heart. To do this, the college is working with the Wellcome Belief, a significant international well being funder, to seek out new companions and funding.

And thankfully, mosnodenvir isn’t the one dengue drug that the pharmaceutical trade is trying into. The Swiss drug maker Novartis is working a section 2 therapy trial for a unique antiviral, and the Serum Institute in India is testing a monoclonal antibody.

Drug improvement is dear and unsure, and the individuals who want dengue therapies most usually are not the individuals who will pay essentially the most. However these steps are encouraging.

In nations the place dengue has all the time circulated — India, Brazil, the Philippines, Sri Lanka — folks have realized to reside round it, says Malavige. Life bends round when the mosquitoes are biting, after which bends again.

However dengue isn’t locked in these locations anymore. Hotter temperatures are carrying the mosquitoes — and the virus — someplace new yearly. And there’s no signal that this enlargement is slowing down.

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