The current tetravalent dengue vaccine TAK-003, from the Japanese laboratory Takeda, is not likely to control the ongoing epidemic, according to the Pan American Health Organization (PAHO). The organization emphasized the need to better understand the vaccine’s effectiveness against different serotypes and its safety under real-world clinical conditions.
The Americas are experiencing a record increase in dengue cases. Three times as many cases have been identified during 2024 (3.5 million) than were reported for the same period in 2023.
“The vaccine we have available will not curb the dengue epidemic; it should be used complementarily with other actions. The most important actions are field operations, vector control, prevention, and education,” said Daniel Salas, MD, executive manager of the PAHO Comprehensive Immunization Program, during a press conference on March 28.
“The vaccines we currently have are not the best response to reduce transmission and prevent deaths,” added Jarbas Barbosa, MD, PhD, PAHO’s director. The fatality rate remains below 0.05%, but this figure could be hard to maintain if the situation becomes more uncontrolled.
The TAK-003 regimen consists of two doses with a 3-month interval between applications, so “it is not a tool to control transmission at this moment. Studies have shown that only 8 years of [population-level] vaccination would have a significant impact on dengue transmission,” said Dr. Barbosa.
A new vaccine developed in Brazil in partnership with the company MSD, Butantan-DV, is in phase 3 trials and has the advantage of being a single-dose application, which could facilitate its use in situations with accelerated transmission. “But this vaccine will likely only be available in 2025,” said Dr. Barbosa.
PAHO officials also highlighted the need to better characterize the vaccine’s effectiveness and safety in the real world. They observed, for example, that when TAK-003 was investigated, the circulation of dengue serotype 3 was almost nonexistent, so the efficacy data against that serotype “are very limited.”
“The producer, Takeda, has very limited production capacity. Brazil is the country that uses this vaccine the most, followed by Argentina. Given that these countries have a good epidemiological surveillance system and adverse effect registration, they can conduct studies on how the vaccine performs in real life, which will greatly increase our knowledge about it. For example, we will see its effectiveness against serotype 3,” said Dr. Barbosa.
The PAHO Technical Advisory Group (TAG) on vaccine-preventable diseases recommended that any country using these vaccines have surveillance systems in place because it is important to promptly report and investigate any adverse events, said Dr. Salas. The organization also suggested that vaccination should ideally be administered in a “more controlled environment,” a phase 4 study, “to complete the safety and efficacy profile, especially in those who have not had dengue before and for dengue 3 and 4,” said Dr. Salas in response to a question from this news organization.
“People cannot expect that just because they were vaccinated, they will not get dengue. The vaccine has limited reach,” he emphasized.
Other research strategies for vector control, such as the use of the Wolbachia bacteria and mosquito sterilization, are future strategies and “not tools to control this outbreak,” noted Sylvain Aldighieri, MD, director of the Department of Prevention, Control, and Elimination of Transmissible Diseases at PAHO.
In his opening remarks, Dr. Barbosa urged the intensification of efforts with tools that are already available. These approaches include eliminating mosquito breeding sites (“80% are in or near homes”) and protecting against mosquito bites, preparing health services for early diagnosis and timely clinical management, and educating the population about dengue symptoms so they seek medical attention immediately.
Although dengue is increasing throughout Latin America and the Caribbean, the most affected countries are Brazil (83%), Paraguay (5.3%), and Argentina (3.7%), which account for 92% of the cases and 87% of the deaths, PAHO reported.
This story was translated from the Medscape Spanish edition using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article appeared on Medscape.com .