Dengue vaccine found to worsen disease symptoms

By Ben Tinker, CNN

Updated 1631 GMT (0031 HKT) December 5, 2017

Dengue virus is carried by the Aedes aegypti mosquito, the same type that can spread Zika virus. A bite from a mosquito harboring the virus can result in headaches, rashes and severe joint pains. In serious cases, it can cause internal bleeding and death.
Photos: Dengue fever: How a mosquito infected millions
Dengue virus is carried by the Aedes aegypti mosquito, the same type that can spread Zika virus. A bite from a mosquito harboring the virus can result in headaches, rashes and severe joint pains. In serious cases, it can cause internal bleeding and death.
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There is no drug for dengue. Patients must be monitored carefully for the onset of the severe form of dengue. Pictured, a nurse looks after a patient with dengue at a hospital in Manila, Philippines.
Photos: Dengue fever: How a mosquito infected millions
There is no drug for dengue. Patients must be monitored carefully for the onset of the severe form of dengue. Pictured, a nurse looks after a patient with dengue at a hospital in Manila, Philippines.
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The main control measures for dengue to date have been to reduce the numbers of mosquitoes by large-scale spraying of insecticides. The chemicals have been deployed in both residential and public spaces in a mass culling of the insects spreading the disease.
Photos: Dengue fever: How a mosquito infected millions
The main control measures for dengue to date have been to reduce the numbers of mosquitoes by large-scale spraying of insecticides. The chemicals have been deployed in both residential and public spaces in a mass culling of the insects spreading the disease.
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Urbanization has aided the spread of dengue, with more than 100 countries now endemic for the disease. Pictured, containers, bottles and tires are perfect breeding sites for Aedes aegypti mosquitoes that transmit the dengue virus. The versatile mosquitoes can lay eggs on any shallow surface of water.
Photos: Dengue fever: How a mosquito infected millions
Urbanization has aided the spread of dengue, with more than 100 countries now endemic for the disease. Pictured, containers, bottles and tires are perfect breeding sites for Aedes aegypti mosquitoes that transmit the dengue virus. The versatile mosquitoes can lay eggs on any shallow surface of water.
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Public spraying of insecticides is based on seasonal changes, with more cases expected during rainy seasons in the tropics. But the measures haven't proven to curb the spread of disease adequately.
Photos: Dengue fever: How a mosquito infected millions
Public spraying of insecticides is based on seasonal changes, with more cases expected during rainy seasons in the tropics. But the measures haven't proven to curb the spread of disease adequately.
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Experts believe a vaccine is needed to truly control the disease. A dengue vaccine, called Dengvaxia, recently became available in Mexico, Brazil, the Philippines and El Salvador.
Photos: Dengue fever: How a mosquito infected millions
Experts believe a vaccine is needed to truly control the disease. A dengue vaccine, called Dengvaxia, recently became available in Mexico, Brazil, the Philippines and El Salvador.
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Story highlights

  • The Philippines has halted a massive dengue fever vaccination effort
  • The country has launched an investigation into the approval of Dengvaxia

(CNN)The Philippines has suspended its large-scale dengue vaccination effort amid the surprising results of a new study conducted by the vaccine's manufacturer.

On Wednesday, French pharmaceutical giant Sanofi Pasteur published clinical trial data showing that its dengue vaccine, Dengvaxia, could have unintended consequences in patients who had never been infected with the mosquito-borne virus.
    "The analysis confirmed that Dengvaxia provides persistent (protective) benefit against dengue fever in those who had prior infection," Sanofi said in a statement. "For those not previously infected by dengue virus, however, the analysis found that in the longer term, more cases of severe disease could occur following vaccination upon a subsequent dengue infection."
      New dengue vaccine could instead cause more cases, experts warn