The World Health Organization (WHO) in Geneva, Switzerland, put the brakes on implementation of the world’s first dengue vaccine today when it recommended it only be used in people who have previously been infected with the disease—a move that will shrink the potential market for the vaccine’s producer, Sanofi Pasteur.
Dengue is most dangerous when a person is infected a second (or subsequent) time. Studies have shown that giving the vaccine to people who have never been infected before can leave them vulnerable to a severe reaction if they are subsequently infected. (The vaccine doesn’t confer full protection to the virus.)
The new recommendation, announced today by WHO’s Strategic Advisory Group of Experts (SAGE) on Immunization, is consistent with a warning that Sanofi Pasteur announced in November 2017. But some observers worry that the recommendation could mean the end of the vaccine. No rapid, reliable test for previous dengue infection is available, so the new guidelines mean that the vaccine can’t be widely used; that could lead the company to stop making the vaccine. So far, however, Sanofi Pasteur has expressed confidence in the vaccine
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