The outbreak of dengue fever that has unfolded in Latin America over the previous three months is staggering in its scale — one million instances in Brazil in a matter of weeks, an enormous spike in Argentina, a state of emergency declared in Peru, and now one other, in Puerto Rico.
It forewarns of a altering panorama for the illness. The mosquitoes that unfold dengue thrive in densely populated cities with weak infrastructure, and in hotter and wetter environments — the kind of habitat that’s increasing shortly with local weather change.
Greater than 3.5 million instances of dengue have been confirmed by governments in Latin America within the first three months of 2024, in contrast with 4.5 million in all of 2023. There have been greater than 1,000 deaths up to now this yr. The Pan-American Well being Group is warning that this can be the worst yr for dengue ever recorded.
The quickly shifting illness panorama wants new options, and researchers in Brazil delivered the lone shred of fine information on this story with the latest announcement {that a} scientific trial of a brand new dengue vaccine, delivered in a single shot, had supplied robust safety towards the illness.
There are two present vaccines for dengue, however one is an costly two-shot routine, whereas the opposite can solely be given to individuals who have already had a dengue an infection.
The brand new one-shot vaccine makes use of reside, weakened types of all 4 strains of the dengue virus, and it was created by scientists on the Nationwide Institutes of Well being in the USA. The vaccine was licensed for growth by the Instituto Butantan, an enormous public analysis institute in São Paulo, and Merck & Co.
Butantan will make the vaccine. It already produces many of the immunizations utilized in Brazil, and has the capability to make tens of hundreds of thousands of doses of this new one. The institute plans to submit the dengue vaccine to Brazil’s regulatory company for approval within the subsequent few months and will start producing it subsequent yr.
However that received’t assist with this outbreak, and by the point the manufacturing gears up and a nationwide rollout will get began, it might not be sufficient to assist with the subsequent one, both; dengue sometimes surges in three- or four-year cycles.
And it received’t essentially be of assist to the remainder of Latin America: Butantan will solely make the vaccine for Brazil. Different international locations within the area scuffling with dengue should buy it from Merck, which has not stated what it plans to cost for the shot.
And there may be, in fact, demand for a dengue vaccine past the Americas: mosquitoes are spreading the illness to Croatia, Italy, California and different areas that haven’t seen it earlier than. Locations used to dealing with gentle outbreaks now face record-breaking ones: Bangladesh had 300,000 instances final yr.
Dengue is usually identified by the title breakbone fever, after the excruciating joint ache it causes. Not everyone experiences that ache: Three-quarters of individuals contaminated with dengue don’t have any signs in any respect, and amongst those that do, most instances resemble solely a light flu.
However about 5 p.c of people that turn into sick will progress to what’s known as extreme dengue. Plasma, the protein-rich fluid part of blood, can begin to leak out of blood vessels, inflicting sufferers to enter shock or endure organ failure.
When sufferers with extreme dengue are handled with blood transfusions and intravenous fluids, the mortality price tends to be between 2 and 5 p.c. However after they don’t get remedy — as a result of they don’t notice it’s dengue and don’t search remedy shortly sufficient, or as a result of well being facilities are overwhelmed — the mortality price is 15 p.c.
In Brazil, the present dengue outbreak is hitting kids hardest; these below 5 have the best mortality price of any age group, adopted by these aged 5 to 9. Adolescents between 10 and 14 have the best variety of confirmed instances, in response to the Instituto Oswaldo Cruz, a nationwide public well being analysis middle.
As clinics started to be overwhelmed with dengue sufferers in January, the Brazilian authorities purchased the whole international inventory of a Japanese-made vaccine for dengue known as Qdenga. Public well being nurses are delivering it to kids ages 6 to 16, however there’ll solely be sufficient vaccine to totally vaccinate 3.3 million of Brazil’s 220 million folks this yr.
This huge nationwide effort will shield a number of million kids, however it received’t contribute something to its herd immunity.
Qdenga isn’t low-cost: It’s about $115 per dose in Europe and $40 in Indonesia. Brazil is paying $19 per dose, having negotiated a cheaper price for its big buy.
Takeda Prescription drugs, which makes Qdenga, introduced a deal final month with Organic E, a big Indian generic drug maker, to license and produce as much as 50 million doses a yr, a part of a race to speed up manufacturing. The Indian vaccine ought to price significantly much less. However Organic E is unlikely to have regulatory approval to promote it earlier than 2030; it’s a sluggish course of that entails transferring know-how, organising a manufacturing line and getting a brand new model of even a well known product accredited by regulators.
Dengue prices Brazil at the least $1 billion a yr in well being care remedy and misplaced productiveness. And that determine doesn’t keep in mind the human struggling concerned.
There are 4 totally different strains of the dengue virus, which complicate greater than the method of creating a vaccine: The doubtless deadly type of the illness is extra frequent when an individual has a second an infection, with a special pressure than they’d the primary time. Qdenga protects towards all 4 strains of dengue, and the hope is that the brand new Butantan vaccine does too, though the information launched up to now present it examined solely towards the 2 varieties that had been circulating throughout the first a part of the trial; extra outcomes are anticipated in June.
Tens of millions extra folks could have been uncovered to dengue when this outbreak lastly passes. However they’re going to wish that new vaccine extra urgently than ever.
