Vaccine for Dengue Would Increase Infections Drastically

A study conducted by researchers from Oregon State University, along with Clemson University, and published in the journal Epidemiology and Infection, showed that a vaccine for dengue fever would actually increase the rates of dengue infection during its first few years.

Analysis suggested that should a vaccine for dengue fever be widely used, it could spike the incidences of the disease as much as 7 times more than what is considered its normal level.


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Researchers created a mathematical model that was able to predict dengue infection patterns after vaccination. This computer model was specifically designed to look at dengue fever, but it could be used with other diseases as well.

More than 50 million people are affected by this mosquito borne disease around the globe every year. Most commonly found in tropical and subtropical regions, dengue fever is rarely fatal, but because there are several different strains of this virus, being infected once does not mean that one is immune. Sometimes a second exposure does the trick. For example, in Thailand, about 80 percent of children have had dengue fever twice and develop immunity before they are 11 years of age.

The problem is that, if a vaccine is developed and distributed, it will, of course, provide some protection but it will interrupt the steady rate of infection, and therefore immunity, among children.

Dengue fever causes high temperatures, intense joint pain, and severe headaches. Although, as with many viruses, there is no cure and no treatments to prevent this illness, researchers believe that children who have been exposed once to this disease show the most promise for success using the vaccine.

This computer model, which assumes that, the same as other vaccines, a vaccine for dengue fever would be less than 100 percent effective. In fact, this vaccine currently only shows a 56 percent rate of being effective. It assumes that a vaccination program would, initially, reduce the rate at which children contract this virus. However, at some time, the natural changes in the mosquito population would eventually expose children to this disease again. Now, because the children who had received vaccinations would have lower immunity levels than those who actually had had the disease earlier, this would increase the infection rates.

Of course, all things can vary, but given the right circumstances, dengue infection rates could go as high as 7 time’s pre-vaccination levels, which would absolutely overwhelm doctors, hospitals, and other health care facilities.

This new study gives a bold example of the law of unexpected consequences, which means that you never really know what might happen when you try to interfere with natural procedures. Another good example of this is the way that infection rates from dengue fever actually increased after Brazil introduced genetically modified mosquitoes to fight this disease.

These GM mosquitoes are all males. They carry a gene in their sperm that ensures that all their offspring will die before they reach sexual maturity. When these GM mosquitoes were first introduced, biologists warned that by killing off mosquitoes that carry dengue fever would actually increase the number of people infected as their natural immunity would be affected. As predicted, this is what appears to be happening in Brazil.

Another issue with these GM mosquitoes might end up being related to the dengue vaccine; the most dangerous form of this disease, which is dengue hemorrhagic fever, is common with those who become infected twice, but have long time intervals between infections. Disrupting the natural rate of infection, regardless of whether it’s via vaccines or GM mosquitoes, could actually change dengue fever into something much more deadly than it currently is.