The Zika outbreak in Latin America may blow through like a nasty storm, moving off in another year or 18 months, a new study suggests.
In any one place the wave of transmission could last between six months and a year, researchers suggested in the study, published in the journal Science.
If these estimates are right, they represent good news and bad news. Women trying to hold off on getting pregnant because of the risk Zika poses to fetuses may have to wait less time before they can try to have children.
But a quick departure will make it tough for scientists to develop a Zika vaccine: if Zika virus isn’t circulating, you cannot prove a vaccine protects against it.
“This epidemic is not going to sustain itself at this level of transmission for very long,” said lead author Neil Ferguson, of MRC Center for Outbreak Analysis and Modeling, at Imperial College, London.
“It is going to burn itself out. And in several areas of the continent it is already in sharp decline. It could really be over by the end of next year.”
Ferguson is a leading infectious diseases modeler; he and his colleagues use mathematical models to try to predict patterns of diseases.
If the prevailing assumption about Zika is correct — that infection leads to life-long immunity — an explosive epidemic of the type sweeping through much of South and Central America could leave many people immune to the virus in a short period of time.
You would not, then, expect the virus to be able to cause additional outbreaks for quite some time, until enough children are born who haven’t been exposed. The paper suggests that might be 10 years but Ferguson said that figure is conservative and the intervals between Zika outbreaks could actually be longer.
Veteran dengue virus expert Dr. Scott Halstead has actually predicted decades may pass between Zika outbreaks, noting that is the way another similar virus, chikungunya, behaves.
Ferguson and his coauthors note that some factors could influence whether their estimate is right. For instance, measures taken to try to reduce the number of mosquitoes that can spread the virus — if they work — could actually stretch out the epidemic. If mosquito control efforts slow transmission, it will take lower to develop the levels of immunity in a population needed to stop the virus from spreading.
“You might get fewer microcephaly cases” in the short term, Ferguson told STAT. “The downside of it is that … you end up with a population that is less immune than it would otherwise have been at the end of the epidemic.”