Despite the billions being spent by the governments of dozens of Latin American countries, Zika—a global epidemic linked to birth defects in an estimated 4,000 babies in Brazil alone—is “spreading explosively,” according to the World Health Organization. Brazil’s health minister recently admitted the country was “badly losing” the fight against the virus. Some tactics, though, show more promise than others.
Global health’s battle plan:
Pregnancy Prevention
Because Zika is most dangerous to unborn babies, governments have asked all women to delay pregnancy—a daunting task given the limited access to birth control in affected regions. The UN estimates that expanding access to contraception would cost $1.7 billion annually.
Vaccines
Drugmaker Inovio Pharmaceuticals (INO) expects to have the first Zika vaccine ready for human testing by the end of 2016. Sanofi also has a program, and GlaxoSmithKline (GSK), Merck (MRK), Pfizer (PFE), and Johnson & Johnson (JNJ) are all evaluating their technologies for such a vaccine.
Eradication
Because pesticides can do only so much, U.K. company Oxitec created a genetically modified mosquito that’s unable to produce fertile offspring once released into the wild. The WHO has said the controversial tactic is safe for humans.
A version of this article appears in the March 1, 2016 issue of Fortune.