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Public health experts are debating how to help the 1 million children in the Philippines who received a new vaccine against dengue that could, in rare cases, sicken rather than protect them. The country launched a campaign in 2016 to vaccinate schoolchildren against the mosquito-borne virus, which can cause fevers, muscle and joint pains, and rashes. One year later, the campaign was suddenly halted after the vaccine’s producer, Paris-based Sanofi Pasteur, announced it could, in rare cases, trigger severe, potentially fatal forms of dengue in children who became infected with the virus despite their vaccination.

Now, critics of the vaccine, named Dengvaxia, say researchers should try to identify those at increased risk of harm, which might save their lives. But Sanofi Pasteur has no plans to conduct a big, complex study, although it is following the fate of about 1% of the vaccinated children for 5 years. “I’m pretty alarmed by the lack of interest,” says retired dengue researcher Scott Halstead, who worked at the Uniformed Services University of the Health Sciences in Bethesda, Maryland, for many years. Halstead calculates that some 500 Filipino children annually could develop severe dengue because of their earlier vaccination with Dengvaxia.

The danger stems from the fact that dengue virus has four distinct variants, or serotypes. More than 40 years ago, Halstead found that people who had antibodies against one serotype had a much higher risk of developing life-threatening disease, including shock or hemorrhagic fever, if they later became infected by a second serotype, a phenomenon called antibody-dependent enhancement (ADE). He has long cautioned that Dengvaxia, which triggers production of these antibodies, might have the same effect in people not fully protected by it.

…continue reading ‘The Controversy Over Dengue Vaccine Risk’

Thumb image via Science PHOTO: AP PHOTO/BULLIT MARQUEZ

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