As of June 30, there have been 1,674 cases of Zika-related microcephaly as it has spread across South and Central America. Although there is no current vaccine for the disease, experimental ones have just begun early-stage clinical trials. However, the epidemic will probably end before these vaccines are available for public use due to a concept known as herd immunity.
This refers to a feature of any such viral or bacterial epidemic, wherein enough people will develop a natural resistance to the disease after being previously infected. Without a “fresh” population to infect, the number of new infections drops down to sub-epidemic levels, and one study suggests this will cause the current epidemic to cease within the next three years, with no resurgence for at least a decade after that.
“It is interesting and important to note that both our paper and theirs rely heavily on the concept of herd immunity,” Perkins added. “The result of our work is a projection of how strong or how weak herd immunity is likely to be in different areas. Overall, I would say that these two studies… are actually quite complementary.”
This means that although herd immunity will likely be the method by which Zika meets its perhaps temporary end, it will not come into effect quick enough to prevent up to as many as 1.65 million childbearing women from contracting the disease – once again highlighting how the next few years pose a huge risk to expectant mothers.
Mosquitos are the primary vector for the virus. tavizta/Shutterstock