Just days after the news surfaced that Zika is being transmitted in the continental U.S., the National Institutes of Health (NIH) announced the start of a phase I human trial for a Zika vaccine.

According to a statement, the sub-agency National Institute of Allergy and Infectious Diseases (NIAID) worked quickly to get the vaccine to trial as the so-far untreatable and unpreventable virus has spread to more than 50 countries.

This vaccine is modeled after a similar NIH-developed West Nile vaccine that injects pieces of virus DNA into the body so immune cells will learn to identify and attack real Zika cells, should the two ever come in contact.

About healthy 80 participants between ages 18 and 35 will get injected with the vaccine at trial centers in Bethesda, Maryland, Baltimore and Atlanta. Different groups will receive differently timed doses to give a more comprehensive view of their immune responses. They’ll be monitored within a 10-month time frame to make sure the vaccine is safe and then checked for an immune response at 18 and 24 months post-injection.

Preliminary results should be available by January, said the statement. If all goes well, phase II trials could begin in at-risk countries early next year.

But stopping the virus is a goal not just in Central and South American countries and U.S. territories, but also now in the U.S.

“A safe and effective vaccine to prevent Zika virus infection and the devastating birth defects it causes is a public health imperative,” NIAID Director Anthony S. Fauci, MD, said in the statement.

Local transmissions of the virus have been detected in some areas of Miami, the CDC warned July 29. At least four Zika infections were determined to have come from bites from local mosquitos, while the other nearly 1,700 cases so far detected in the U.S. were the result of travel or sexual transmission.

CDC officials reiterated the need to watch and possibly contain certain mosquito species, for people, especially pregnant women, to avoid being bitten and to see a doctor if they believe they’ve been infected. Additionally, the agency issued a travel warning for the Miami neighborhoods from which the transmissions are believed to have come, similar to the foreign travel advisories is has issued for other Zika-present areas.

“With the new information that there are active mosquitoes still in the area and additional Zika infections, we conclude that pregnant women should avoid this area—and make every effort to prevent mosquito bites if they live or work there,” CDC Director Tom Frieden, MD, MPH, said in a statement.

At least seven CDC officials plus state representatives will work on the ground in Florida to try to limit the spread of the virus.

And in a further effort to stem that expansion, the CDC is also sending $16 million to 40 states to improve preparedness measures, it announced August 2.