The Push for a Better Dengue Vaccine Grows More Urgent

The dengue epidemic that has broken out in Latin America over the last three months is of staggering scale: a million cases in Brazil in a few weeks, a sharp increase in Argentina, a state of emergency declared in Peru and now another. , in Puerto Rico.

This warns of a changing landscape for the disease. The mosquitoes that spread dengue thrive in densely populated cities with weak infrastructure, as well as warmer, more humid environments – a habitat type that is growing rapidly with climate change.

More than 3.5 million cases of dengue fever have been confirmed by Latin American governments in the first three months of 2024, compared to 4.5 million for all of 2023. There have been more than 1,000 deaths so far this year. The Pan American Health Organization warns that this year could be the worst year on record for dengue fever.

The rapidly evolving disease landscape needs new solutions, and Brazilian researchers delivered the only good news in this story with the recent announcement that a clinical trial of a new dengue vaccine, administered in a single injection, had provided strong protection against the disease. .

There are two dengue vaccines, but one is an expensive two-shot regimen, while the other can only be given to people who have had a previous dengue infection.

The new single-shot vaccine uses live, weakened forms of all four strains of the dengue virus and was created by scientists at the US National Institutes of Health. Development of the vaccine was authorized by the Instituto Butantan, a huge public research institute in São Paulo, and Merck & Co.

Butantan will manufacture the vaccine. It already produces most of the vaccines used in Brazil and has the capacity to manufacture tens of millions of doses of this new vaccine. The institute plans to submit the dengue vaccine to Brazil’s regulatory agency for approval in the coming months and could begin producing it next year.

But it won’t help fight this outbreak, and by the time production gears up and a national rollout begins, it might not be enough to help with the next one either; Dengue usually appears in cycles of three or four years.

And it won’t necessarily help the rest of Latin America: Butantan will only make the vaccine for Brazil. Other countries in the region battling dengue fever will have to buy it from Merck, which did not say what price it planned for the vaccine.

And there is, of course, demand for a dengue vaccine beyond the Americas: Mosquitoes are spreading the disease in Croatia, Italy, California and other areas that have never experienced it before. Places accustomed to handling mild outbreaks are now facing record outbreaks: Bangladesh recorded 300,000 cases last year.

Dengue fever is commonly known as broken fever, due to the excruciating joint pain it causes. Not everyone feels this pain: three-quarters of people infected with dengue have no symptoms, and of those who do, most cases only resemble a mild flu.

But about 5 percent of people who get sick will progress to what’s called severe dengue. Plasma, the protein-rich liquid component of blood, can begin to leak from blood vessels, causing shock or organ failure in patients.

When patients with severe dengue are treated with blood transfusions and intravenous fluids, the mortality rate tends to be between 2 and 5 percent. But when they don’t get treatment – ​​because they don’t realize it’s dengue and don’t seek treatment quickly enough, or because health centers are overwhelmed – the mortality rate reaches 15 percent.

In Brazil, the current dengue epidemic is hitting children hardest; Those under 5 years old have the highest mortality rate of all age groups, followed by those aged 5 to 9 years old. Adolescents between 10 and 14 years old have the highest number of confirmed cases, according to the Instituto Oswaldo Cruz, a national public health research center.

As clinics began to be overwhelmed with dengue patients in January, the Brazilian government purchased the world’s entire stock of a Japanese-made dengue vaccine, called Qdenga. Public health nurses administer it to children ages 6 to 16, but there will only be enough vaccine to fully inoculate 3.3 million of Brazil’s 220 million people this year.

This great national effort will protect a few million children, but it will contribute nothing to collective immunity.

Qdenga is not cheap: it costs around $115 per dose in Europe and $40 in Indonesia. Brazil pays $19 per dose, after negotiating a lower price for its huge purchase.

Takeda Pharmaceuticals, which makes Qdenga, announced a deal last month with Biological E, a major Indian generic drugmaker, to license and produce up to 50 million doses a year, part of a race to to speed up production. The Indian vaccine is expected to cost much less. But Biological E is unlikely to gain regulatory approval to market it before 2030; it is a slow process that involves technology transfer, setting up a production line and getting a new version of even a well-known product approved by regulators.

Dengue costs Brazil at least $1 billion a year in health care and lost productivity. And this figure does not take into account the human suffering involved.

There are four different strains of the dengue virus that further complicate the process of making a vaccine: The potentially fatal form of the disease is more common when a person has a second infection, with a different strain than the one they had the first time. Qdenga protects against all four strains of dengue, and it is hoped that the new Butantan vaccine will too, although data published so far shows that it has only been tested against the two types that were circulating during the first part of the essay; further results are expected in June.

Millions more people will have been exposed to dengue fever when this epidemic finally passes. But they will need this new vaccine more than ever.

News Source :
Gn Health

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