The risks from Zika virus sweeping through the Americas are serious enough that some countries are telling their citizens to put off getting pregnant for months or even years.
It’s an extraordinary response to the mosquito-borne virus suspected of causing babies to be born with abnormally small heads, a birth defect known as microcephaly. “When you have no other tools to use right now, that’s about the best advice you can give,” said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.
But it adds a question to the long list of things we don’t know about this epidemic: If it’s not considered safe to get pregnant now, when will it be?
The World Health Organization said on Sunday that it expects the virus to reach parts of every country in the Americas except for Canada and continental Chile, the two places that aren’t home to the type of mosquitoes that spread Zika. In El Salvador, officials suggested women delay conception until 2018. Colombia, Ecuador, and Jamaica called for shorter delays. The virus hasn’t even been confirmed in Jamaica yet. The U.S. Centers for Disease Control and Prevention has advised women to consider postponing travel to Zika-affected areas and to take precautions against mosquito bites if they do.
But no one knows how long it will take to get Zika under control. Osterholm points to the pattern of chikungunya, a similar virus carried by the same mosquitoes that first began to circulate locally in the Americas in December 2013, with transmissions on the Caribbean island of St. Martin. Two years later, “we still see substantial transmission of chikungunya,” Osterholm said.
Put aside for a minute that an estimated 58 percent of pregnancies in Latin America are unintended. For women who do plan their pregnancies, the suggestion to delay during the Zika epidemic poses a tough dilemma, because there’s no guarantee that the risk of getting the virus or of consequent birth defects will be any lower in six months or two years. But here’s what’s likely to happen:
1. We’ll know more in a few months
Right now, scientists can’t calculate the risk that contracting Zika during pregnancy will have negative consequences for the unborn child. “We’d want to know if the risk was 1 in 10,000; 1 in 1,000; or 1 in 50,” said William Schaffner, an infectious disease specialist at Vanderbilt University School of Medicine. There were about 3,500 cases of microcephaly reported in Brazil from October through mid-January, according to CDC officials, roughly a twentyfold increase from historical rates. (To put that in perspective, Brazil sees about 3 million births a year, according to Unicef.) It’s also unclear whether the Zika virus can affect a fetus even if a pregnant woman is bitten by a Zika-carrying mosquito but never develops symptoms. Researchers are urgently trying to answer these questions.
2. More people will likely develop natural immunity to Zika
The virus is spreading so quickly because it’s in a part of the world that had never seen Zika before. Symptoms such as joint pain, rash, and fever are usually mild, and people recover after a brief illness. Although researchers haven’t proved that surviving one bout of Zika confers immunity, it appears to be the case based on previous outbreaks. If the virus affects most people who are susceptible in the next year or two, women may be naturally immune before they conceive, Schaffner said.
3. There should be better diagnostics, or even a vaccine
There are no easy, widely available tests to determine if someone has Zika or whether they’ve been inoculated to the virus. If in a year or two there’s a simple blood test that can tell if someone is susceptible to Zika, that could reassure women who are considering pregnancy, Schaffner said. Eventually there may even be a vaccine to prevent infection. Osterholm said that would be unlikely in two years, calling the chances of getting a vaccine in that period “extremely, extremely optimistic.”
Schaffner said he won’t be surprised if more countries recommend delaying pregnancy, but he doesn’t expect every Zika-affected nation to do so. It may be a while before women have good answers to the difficult questions the virus poses. That some governments are telling their citizens to put off having children shows how troubling those questions are.