The shadow of the Zika virus hangs over the Rio Olympic Games, with visitors and even high-profile athletes citing worries about Zika as a reason to stay away (even if the risk is probably quite low). The public’s concerns are a striking example of the need to rapidly combat emerging infectious diseases.

In the fight against Zika, public health experts have turned to what may sound like an unlikely ally: genetically modified organisms, or GMOs.

Consumers are used to hearing about GMOs in food crops, but may be unaware of the vital role GMOs play in medicine. Most modern biomedical advances, especially the vaccines used to eradicate disease and protect against pandemics such as Zika, Ebola and the flu, rely on the same molecular biology tools that are used to create genetically modified organisms. To protect the public, scientists have embraced GMO technology to quickly study new health threats, manufacture enough protective vaccines, and monitor and even predict new outbreaks.

Vaccines, meet molecular biology

Vaccines work with the immune system to strengthen the body’s own natural defenses. A vaccine offers a preview of a potential infection, so the immune system is ready to pounce if the real threat shows up.

The earliest vaccines were primitive – think Edward Jenner in the 1790s inoculating against smallpox by rubbing together the open wounds of uninfected patients and those with cowpox. But over the years, advances in medical technology led to improved vaccines. The modern age of vaccines was ushered in by the introduction of molecular biology tools in the 1970s, which vastly improved our ability to study and manipulate viruses.