The dengue outbreak that has occurred in Latin America over the past three months is staggering in its scale. In Brazil, the number of infected people reached 1 million in a few weeks, in Argentina the number of infected people increased significantly, in Peru a state of emergency was declared, and now there are new cases. , in Puerto Rico.
It heralds a change in the status of this disease. The mosquitoes that spread dengue breed in densely populated cities with weak infrastructure and in warmer, wetter environments that are rapidly expanding as the climate changes.
The number of dengue fever cases confirmed by governments in Latin America exceeded 3.5 million in the first three months of 2024, and 4.5 million in all of 2023. More than 1,000 people have died so far this year. The Pan American Health Organization has warned that this year could be the worst year for dengue in history.
The rapidly changing disease landscape requires new solutions, and Brazilian researchers say clinical trials of a new dengue vaccine administered in a single dose provided strong protection against the disease. A recent announcement provided the only good news in this article. .
There are two existing vaccines for dengue; one is an expensive two-dose shot and the other can only be given to people who have already had dengue.
The new one-shot vaccine uses live, attenuated vaccines of all four strains of the dengue virus and was created by scientists at the US National Institutes of Health. The vaccine was approved for development by the Butantan Institute, a large public research institute in São Paulo, and Merck & Co.
Butantane will make a vaccine. The company already makes most of the shots used in Brazil and has the capacity to produce tens of millions of doses of this new vaccine. The institute plans to submit its dengue vaccine to Brazilian regulators for approval in the coming months, and production could begin next year.
However, that won't help with the current outbreak, and by the time production ramps up and nationwide rollout begins, it may not be enough to prevent the next outbreak. Dengue fever typically spikes in three- or four-year cycles.
And that doesn't necessarily help the rest of Latin America. Butantan will only manufacture vaccines for Brazil. Other countries in the region suffering from dengue fever will have to buy vaccines from Merck, which has not said how much it plans to charge for vaccinations.
And, of course, there is demand for dengue vaccines beyond the Americas. Mosquitoes are also spreading the disease to Croatia, Italy, California, and other areas where the disease was not previously known. Regions used to experiencing mild outbreaks are now facing record outbreaks. Bangladesh had 300,000 infections last year.
Dengue fever is commonly known as breakbone fever, after the excruciating joint pain it causes. Not everyone experiences that pain. Three-quarters of people infected with dengue have no symptoms at all, and most of those who do have only mild flu-like symptoms.
However, about 5 percent of people who become ill progress to what is called severe dengue fever. Plasma, the protein-rich liquid component of blood, begins to leak from blood vessels, and patients may go into shock or suffer organ failure.
When patients with severe dengue fever are treated with blood transfusions or intravenous fluids, mortality rates tend to be between 2 and 5 percent. But if you don't know you have dengue and don't seek treatment right away, or if you can't get treatment because health centers are overwhelmed, the mortality rate is 15 percent.
In Brazil, the current dengue epidemic is hitting children hardest. According to the Oswaldo Cruz Institute, a national public health research center, under-fives have the highest mortality rate of any age group, followed by those aged five to nine. According to the Oswaldo Cruz Institute, a national public health research center, the highest number of confirmed cases are among adolescents between the ages of 10 and 14.
In January, as clinics began to become crowded with dengue patients, the Brazilian government purchased a global stock of a Japanese-made dengue vaccine called Cudenga. Public health nurses are distributing vaccines to children ages 6 to 16, but this year there is only enough vaccine to fully inoculate 3.3 million people out of Brazil's 220 million population.
This massive national effort will protect millions of children but will not contribute to herd immunity.
Qdenga isn't cheap. In Europe it's about $115 a pop and in Indonesia it's $40. Brazil has negotiated lower prices for its huge purchases, paying $19 each.
Last month, Takeda Pharmaceutical, which makes Q-Denga, announced a deal with Biological E, a major Indian generic drug maker, to license and produce up to 50 million doses a year as part of a race to accelerate production. The cost of India's vaccine should be significantly lower. However, Biological E is unlikely to receive marketing approval from regulatory authorities before 2030. This is a time-consuming process of transferring technology, setting up production lines, and obtaining regulatory approval for new versions of even well-known products.
Dengue costs Brazil at least $1 billion a year in medical costs and lost productivity. And that number doesn't take into account the human suffering involved.
The fact that there are four different strains of the dengue virus is even more complicated than the process of making a vaccine. The potentially fatal disease is common when a person is infected a second time with a different strain than the first time they were infected. . Kudenga protects against all four types of dengue fever, and the new butantan vaccine is expected to protect as well, but data published so far shows no outbreaks occurred in the first part of the trial. It is shown that it was only tested against two types. Further results are expected in June.
When this epidemic finally ends, millions more people will be exposed to dengue fever. But they will need new vaccines more urgently than ever.
