New discoveries demonstrate that vaccination could prompt more severe disease in individuals who have never had an earlier dengue disease. Philippine health authorities have suspended the sale and distribution of Dengvaxia, the world’s first dengue vaccine, following the release of a report raising concerns about the vaccine’s safety in people who have never been infected with dengue.
The new discoveries, reported by vaccine creator Sanofi Pasteur on November 29, confirmed that Dengvaxia gives a “persistent protective advantage” for the individuals who have previously been infected with dengue.
In individuals who have never had dengue, however, vaccination could prompt more instances of severe disease upon a subsequent natural infection with the virus, said the report. While the first infection with one of the four dengue infection serotypes is regularly mellow, a moment disease with an alternate serotype can cause severe disease; it is thought that the body’s immune response to the first infection improves the second.
The Sanofi report adds to previous clinical trial information showing that the vaccine was related to an increased risk of hospitalization for children under than nine. As indicated by a 2016 study published in Science, one possible reason behind this result is that the vaccine mimics the first infection in people who have never been exposed to dengue, along these lines setting them up for more severe disease upon a subsequent natural infection.
The symptoms of severe dengue include fever lasting for no less than two days, low platelet count, bruising and severe bleeding. Severe dengue is among the leading causes of death in many Southeast Asian and Latin American nations.
In any case, Dr. Ng Su-Peing, Sanofi’s global medical head, said during a press conference on December 4 that vaccine-related severe dengue cases would be relatively uncommon.
“To see even one additional severe dengue case among the individuals who have never seen a dengue infection, you would need to vaccinate 5,000 individuals where the vast majority of having seen disease earlier and one out of ten hasn’t.”
“The overall advantage of vaccination in a highly endemic setting, for example, what we have here in the Philippines is still in accordance with the World Health Organization (WHO) recommendation for vaccination introduction,” she said.
However, Ng does not recommend the vaccine for the individuals who have never been infected with dengue virus. The WHO, for its part, has advised that, pending a full report on its efficacy and safety, the vaccine should just be taken off in populaces with a high prevalence of dengue infection.
“You need to take a look at the local information, local epidemiology, and the burden of the country in the nation, what extents of the populace in a given nation have had previous dengue. From the government information in the Philippines, no less than the vast majority of children, when they reach adolescence, have had dengue,” said Ng.
She included that dengue infection can be hard to see, as the greater part of infected people show no symptoms.
The press conference came after the Philippine Department of Health (DOH) declared that it would put on hold its dengue vaccination program until “specialists are able to review new developments on the Dengvaxia dengue vaccine.”
In a separate press conference, DOH spokesperson Dr. Lyndon Lee-Suy guaranteed the public that the government would keep on monitoring vaccinated children. A series of council meetings are scheduled between the Philippine government and Sanofi Pasteur to discuss the following steps. Lee-Suy said that the WHO’s Strategic Advisory Group of specialists is also set to meet within the week to examine the Sanofi report.
Since 2016, more than 700,000 Filipino children have received Dengvaxia for nothing under the DOH’s school-based immunization program, after the vaccine was licensed by the Philippine Food and Drug Administration.