Sept. 13, 2014 Update
There have been a number of recent sketchy media reports on NPR and the NY Times (Sep. 3 2014) etc on a new Dengue virus vaccine from Sanofi. Unfortunately, company press releases and media reports really don’t contain sufficient details to understand the Sanofi study results. Here are one public health scientist’s views.
The Good News:
~ The new Sanofi vaccine appears to work well against 3 of the 4 strains (serotypes) of Dengue Virus: DV1, DV3, & DV4.
~ This is big news, because no previous attempts at Dengue vaccines have worked against even one strain of Dengue Virus.
~ The ability to give some protection from 3 out of 4 could help people in some areas. . . .
~ Sanofi’s Dengue vaccine does appear safe (NOT causing serious Dengue Fever).
~ Potential protective effects have been shown to last FOR AT LEAST A MONTH after vaccination. ( => monthly re-vaccinations required ~ to assure protection in many patients)
The Bad News:
~ The new Sanofi virus showed no statistically significant difference in reducing Dengue infection is a Phase 2 trial in Thailand using 4002 school children.
~ Strain 2 of Dengue Virus is the strain that has been causing the worst symptoms.
~ Strain 2 of Dengue Virus is very prevalent here in Yucatan.
~ Recent hospitalizations of Dengue Virus infected patients in Yucatan have taken an ugly turn: Many many patients are now coming in with gastro-intestinal bleeding.
~ Because the Sanofi Phase 2 research trials were conducted in Thailand, in an area with lots of Dengue Virus Serotype 2, the Phase 2 research results showed that the vaccine statistically did not reduce Dengue infections vs. the Control Group. e.g. 79 out of 134 of the Dengue Cases in the vaccinated group were caused by Dengue Virus Serotype 2.**
~ Unless we want to get vaccinated monthly, we hope that the vaccine will show some efficacy for at least a year after vaccination.
The story does not end here:
Large scale Phase 3 trials of the Sanofi vaccine (with 31,000 children and adolescents) are continuing in Latin America (Mexico, Colombia, Honduras, Puerto Rico and Brazil) and in Asia (the Philippines, Vietnam, Malaysia, Indonesia, and Thailand). Hopefully, the Phase 3 results will show reductions in Dengue virus infections. There are also large scale field trials using Wolbachia bacteria to infect Aedes Aegypti mosquitoes in Brazil. These Wolbachia bacteria infect the female Aedes Aegypti mosquitoes, and keep the Dengue Virus from reproducing inside the mosquitoes = the Wolbachia bacteria infected mosquitoes do not get nor transmit Dengue Virus.
What does it all mean?
~ It will be 2 years before we know the final results for the Sanofi Dengue vaccine trials, and the Wolbachia bacteria field trial results will also be in.
~ Both the Sanofi vaccine and the Wolbachia bacteria infecting programs show promise in improving our risks of not getting Dengue.
~ Both of these approaches may work for a while, but stopping Mosquito breeding can offer permanent Dengue Virus reductions.
No Mosquitoes = No Dengue ~
~ One conclusion that I would draw for protecting ourselves against Dengue?: Our best defense against Dengue is the clean-up or removal of Aedes Aegypti mosquito breeding sites in our cities and around our homes. Aedes Aegypti mosquitoes love to breed in clean standing water, like in old flower pots, floor drains, dog water dishes, plastic rubbish, piles of plant rubbish, old tires etc. One could also choose to use mosquito traps in their homes or use repellants, especially in the mornings, when our Aedes Aegypti mosquitoes are most active.
Best of luck in avoiding Dengue infections, and keep your homes and yards (mostly) mosquito free. Our efforts here have reduced our exposures to less than one mosquito per week in the house, and only 1-2 mosquitoes outside on our patio.
**For people who do not have a subscription to the Lancet, here is a link to a free pdf version of Sanofi’s Phase 2 research study results. Protective efficacy of the recombinant, live-attenuated, CYD tetravalent dengue vaccine in Thai schoolchildren: a randomised, controlled phase 2b trial
For those interested in our local Yucatan efforts in combating Dengue, you can read an article from yesterday’s Diario de Yucatan, describing our efforts to put insecticide treated curtains in the homes of 450 poor families in Merida and in outlying communities. We have installed curtain rods on roughly 4,500 windows and doors, and we are just now putting up the curtains. Lets hope for good good results in the ongoing blood tests on these poor families, who have agreed to ongoing monitoring of mosquitoes in their homes and ongoing blood testing of the families for Dengue virus infections.
Special thanks to the Colorado State University for their support, and to the US National Institutes of Health for their ongoing financial assistance in these efforts.
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Background: Female “Aedes Aegypti” mosquitoes enter our homes through open doors and windows to find blood meals. After the females have fed (bitten us), they fly back outside to rest, lay eggs in fresh standing water, and then they fly back into our homes to feed again. Insecticide treated curtains have shown 95% knock-down rates when the mosquitoes land on them while going through a doorway or window.
If readers want more information on Dengue Treatment, Dengue virus life cycles, Dengue prevention, and Mosquito prevention, please see our Dengue Fact sheet at: Dengue Fact Sheet – May 2012 Update ~ and also click on the “Science, Tech, and Health” button (above) to read more details.
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© Steven M. Fry
Read on, MacDuff.