Topline
A pill to prevent dengue fever—a viral infection also called “breakbone fever” for the severe pain it can cause—could be on the horizon, according to data presented by Johnson & Johnson on Friday, promising news that could signal a future treatment against what experts warn is a pressing and growing health threat that could soon return to plague the United States.
Female Aedes aegypti mosquitoes are the primary vector of dengue.
Key Facts
An antiviral pill developed by pharma giant Johnson & Johnson appeared to protect people against dengue when exposed to a virus that causes the disease, according to early data from the company’s clinical trial presented at the American Society of Tropical Medicine & Hygiene Annual Meeting in Chicago.
The trial involved healthy volunteers taking the drug—called JNJ-1802—or an inert placebo for 26 days and being injected on day five with a type of dengue virus, a type of study known as a challenge trial.
The participants were monitored over 85 days for signs of dengue infection, including immune responses and detectable virus in the blood, and Johnson & Johnson said the drug was safe and well-tolerated by all participants.
All five people in the placebo group showed detectable virus during monitoring, Reuters reported from the conference, while six out of ten participants receiving a high dose of the drug showed no signs of infection.
While the “promising results” need to be followed up with much larger tests, Marnix Van Loock, who leads emerging pathogens research at the firm’s Janssen branch, said they “offer the hope that science will be able to deliver against this threat” as it becomes an even bigger problem worldwide.
The drug “is the first ever to show antiviral activity against dengue,” Van Loock said, Reuters reported.
What To Watch For
The early findings support the wider Phase 2 clinical trial of the drug to prevent dengue Johnson & Johnson is running in ten countries where there is a risk of dengue, including the Philippines, Thailand, Peru, Brazil and Colombia. The real-world trial, rather than testing the drug on people exposed to a specific dengue virus that has been weakened to minimize symptoms, will assess the drug’s ability to prevent dengue from the four strains of dengue virus circulating.
Tangent
Johnson & Johnson said the drug works by blocking the action of viral proteins and preventing the virus from replicating. While the drug is being tested in this trial as a preventative, that it shows antiviral activity against dengue suggests it could potentially function as a treatment for those already infected. The company said it has plans to test the drug as a treatment in the future.
Key Background
Dengue is a leading cause of illness and death in many parts of the world, particularly in some Asian and Latin American countries. Four different viruses can cause dengue and they are spread through the bites of infected female mosquitoes, primarily the invasive Aedes aegypti, which thrive in warmer climates. Experts warn climate change will help expand the range of the mosquitoes that spread the disease and could help diseases they carry, like dengue, Zika and yellow fevers, take hold across the U.S. and parts of Europe. Around 400 million people are infected every year—experts believe this is a significant underestimate—though most people will not experience any symptoms. The disease can be serious, however, and around a quarter of people with dengue will experience flu-like symptoms such as fever, headache, rash, aches and pains and vomiting that typically begin a few days after infection and last a week or two. These symptoms usually appear in concert with the joint pains and spasms severe enough to justify the nickname breakbone fever. One in 20 of those cases of dengue can rapidly become a medical emergency, and around 40,000 die from dengue each year. There is no treatment and, until recently, prevention has been limited to staving off mosquito bites.
Surprising Fact
Efforts to develop a vaccine for dengue have been hampered by the unusual fact that infection for a second time (with a different dengue virus) is often much more severe. Until recently, a vaccine has only been licensed for people who had already had a confirmed dengue infection as it could otherwise raise the risk of severe dengue. There is now a vaccine for people who haven’t been infected in the past, though its availability is limited and the company withdrew its application to be authorized in the U.S. As with many drugs and preventatives for diseases that affect people in less affluent countries, ensuring equitable access to the vaccines—and any potential drug to come out of Johnson & Johnson’s trial—has become a key issue.
Further Reading
Painful Dengue May ‘Take Off’ In United States—What To Know About The ‘Breakbone Fever’ Virus (Forbes)
