Thursday, April 19, 2018

WHO: Audio Of SAGE Press Conference On Vaccines (including Dengvaxia (tm))


Roughly 5 months ago vaccine producer Sanofi hinted at a safety signal with their Dengvaxia (tm) vaccine (see Philippines Halts Dengue Vaccine After Sanofi Issues Warning) - involving children who had never been infected with dengue, and received the vaccine. 
Recently completed studies suggested that dengue-naive children who received the vaccine were at an increased risk of seeing a `severe dengue infection' months or even years later.  
This news came after roughly 700,000 people received the vaccine in the Philippines, of which as many as 10% may have never been previously infected. Within days of the announcement, the Philippines FDA withdrew the drug from the market amid media reports of potentially injured children.

In December the World Health Organization Unveiled Interim Dengue Vaccine Recommendations, and promised `. . . a full review of the data through the Global Advisory Committee on Vaccine Safety and SAGE, for revised guidance of the use of Dengvaxia®'. 

SAGE has just completed their spring meeting and the audio of a 26 minute press conference discussing that meeting - and their decision on Dengvaxia (tm) - has been posted to the WHO mulimedia web page. 
The upshot is, after reviewing the evidence, SAGE recommends that the Dengvaxia vaccine be given in a`much safer way', meaning that it should only be given to those who can be certified as having previously been infected with one of the dengue serotypes.
Practically speaking, that would require the use of an inexpensive point-of-care rapid test that can be administered just prior to vaccination - a product which is not currently available.     

As we've discussed previously, there have long been concerns over the safety of the dengue vaccine, particularly in regards to a phenomenon called antibody dependent enhancement or ADE.

Generally speaking, a person's first infection with dengue is relatively mild, but with four serotypes, a person can be infected multiple times during their lifetime. A person's second infection with dengue is often more severe due to the body thinking the second infection is the same serotype as the first, and sending inefficient antibodies to fight it.
When given to a dengue-naive individual, the dengue vaccine can substitute for that first infection, and could make a later infection worse.
There were warnings - published in major journals - suggesting just this sort of outcome was possible. One need look no further than a CIDRAP News report from July of 2016, which eerily presages the events of the past few months (see Contrary dengue vaccine response hints at possible problems with Zika).
Regardless of the actual risk of injury from this vaccine (which remains a matter of some debate), Dengvaxia's reputation - and the public's perception of the safety of other vaccines - has taken a significant hit.
Which in the end, could turn out to be the biggest loss of all.

No comments: