Researchers openly admit dengue vaccine would cause 7-fold spike in infections

(NaturalNews) A vaccine for dengue fever would actually increase rates of dengue infection over the first few years, according to a study conducted by researchers from Oregon State University and Clemson University, and published in the journal Epidemiology & Infection.

"Our analysis suggests that if we develop and widely use a vaccine for dengue fever, there may later be spikes in the incidence of the disease that are two to three times higher than its normal level," researcher Jan Medlock said.

At times, use of a vaccine could cause infection levels to increase as much as sevenfold, the study found.

Vaccine less potent than natural immunity

Researchers designed a mathematical model to predict dengue infection patterns following vaccination. Although the computer program was designed to look specifically at dengue fever, the researchers noted that its findings may also be applicable to other diseases.

Dengue fever is a mosquito-borne disease that affects about 50 million people each year worldwide. Although very common in tropical and subtropical regions, the disease is rarely fatal. Because there are several different strains of the dengue virus, being infected a single time does not typically confer lifelong immunity; a second exposure, however, usually does the trick. In Thailand, for example, 80 percent of children have been infected with dengue twice and therefore developed immunity by the age of 11.

"The problem, if and when we develop and use a vaccine, is that it will provide some, but not complete protection, and it will interrupt the natural, fairly steady rate of infections among children," Medlock said.

According to the computer model -- which presumes that, like other vaccines, a dengue vaccine would be less than 100 percent effective -- a vaccination program would initially reduce the rate at which children contracted dengue fever. At some point, however, natural fluctuation in mosquito populations would expose these children to the disease again. Because vaccinated children's immunity would be less than that of people who had actually had the disease, this would create a surge in infection rates.

Given the right cluster of variables, dengue infection rates could jump to as high as seven times pre-vaccination levels, overwhelming healthcare facilities.

Although the specifics of the infection surge from a dengue vaccine are determined by the characteristics of that particular disease, the researchers note that similar effects may have happened in the past, following the introduction of other vaccines.

Could vaccine make dengue more lethal?

The new study provides a vivid example of the law of unintended consequences: You never know what might happen when you interfere with natural processes. Another recent example was the way that dengue fever infection rates actually appear to have increased following the introduction of genetically modified (GM) mosquitoes intended to combat the disease in a region of Brazil.

The mosquitoes are all males engineered to carry a gene in their sperm that kills all their offspring before they reach sexual maturity. When the plan was first announced, biologists and civil society groups warned that killing off dengue mosquitoes could actually increase prevalence of the disease over time, by removing people's natural immunity. Indeed, this already appears to be happening.

Another concern raised with the GM mosquitoes might also be of relevance to a dengue vaccine: The most dangerous form of the disease, dengue hemorrhagic fever, is most common in people who have had dengue fever twice, but with a long gap between infections. Artificially disrupting the natural rate of dengue infection, whether via GM mosquitoes or vaccines, could actually turn dengue fever into a far more lethal disease.

Sources for this article include:

http://oregonstate.edu

http://journals.cambridge.org

http://www.thehindu.com

http://www.naturalnews.com

http://science.naturalnews.com