Thursday, July 17, 2014

THE DENGUE VACCINE - EARLY EXPERIENCE



Yes, I am a cardiologist, but being a civil society activist, I have great interest in this dengue scourge that is upon us, in my opinion, in epidermic proportions. When tens of Malaysians  are dying every month, one has to sit up and take notice and scratch our heads to find a solution.
So when news broke last week that Sanofi has been studying a vaccine and that the first publication is out, I looked around for a copy. My friend found me a copy and so I took a look at it.

The latest issue of Lancet carries the full article.
This study was led by Dr Maria Capeding of the Research Institute for Tropical Medicine in the Philippines and funded by Sanofi. I am only glad to note that two of our paeds Institute ( the Penang Hospital Paeds institute and the HKL paeds institute took part in the study.
Dr Maria and team carried out an observer masked, randomised controlled, multicenter, phase 3 trial in 5 countries in the Asian Pacific Region between June 3 and Dec 1 of 2011. Their aim was to assess the efficacy of the CYD dengue vaccine against symptomatic, virologically confirmed dengue in otherwise healthy children.
They vaccinated 10,275 healthy children ( age 2-14 years ), assigned to receive either vaccine or placebo of which about 10,000 were included in the primary analysis. Those assigned to the treatment arm received 3 injections of recombinant, live attenuated, tetravalent dengue vaccine at 0, 6, 12 months. The cohort was followed up for 25 months.The primary endpoint was the vaccine efficacy against symptomatic virologically confirmed dengue, that took place more than 28 days after the third injection.
From the 10,000 children in the study, about 250 cases ( 2.5% ) of dengue took place 28 days or more after the third injection ( 117 cases in the treatment arm and 133 cases in the placebo arm ). The primary end point was achieved with 56.5% efficacy.
However, the side effects were significant. They recorded 647 serious adverse events ( 402 in treatment arm and 245 in the placebo arm ), some within 28 days of the vaccination. This is not minor. There was one case of acute disseminated encephalomyelitis. There were 4 deaths in the treatment arm and non in the control arm. 3 of the deaths were classify as accident? one of tracheal injury. The numbers all round were small, so may give a skewed picture. Need more numbers to have a fairer picture. Certainly the side effects are not insignificant.

All in all, although we greatly need a vaccine to combat this dengue epidermic that has befallen us, this first attempt leaves much to be desired. A small sample ( 2.5% ) infection in a region infested by the Aedes mosquito must raise a few questions. Why did we not get more cases? A 5.6% protection rate against a serious side effect rate of 6% must also raise an issue?

Looks like this first vaccine is NOT yet ready for primetime. Let us call it an early experience.
I hope that the government is smart enough to see that.


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