The Zika virus is spreading — and the big question is whether it will lead to a huge outbreak in the United States.

Fortunately, experts think that’s unlikely, at least quickly. In comments at the Economic Club of Washington D.C., Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said that the Zika virus isn’t coming up the coast from South America, and there hasn’t been a major outbreak, although he noted that health officials are still taking it seriously, according to an ABC Radio report.

Officials are still preparing for a major outbreak, but they think it’s unlikely.

So where did the Zika virus come from? It is spread through mosquito bites, and it is most dangerous to pregnant women, as it can cause microcephaly in newborn babies, resulting in babies born with small heads and brains, resulting in seizures, vision problems, and problems swallowing, to name a few complications.

Many people who get the virus don’t have any symptoms, but some people experience fever, rash, and conjunctivitis. A travel alert has been issued by the CDC for countries in Central America and South America.

Still, some are calling for the health community to do more about the situation. Lawrence O. Gostin of the O’Neill Institute for National and Global Health Law at Georgetown said in a statement that WHO’s failure to act decisively is what resulted in Ebola getting out of control, and health officials need to learn from their mistakes.

“The critical lesson learned from the WHO’s handling of the Ebola crises was the need for early and decisive action,” he said. “Yet WHO, and even advanced countries like the United States, were caught off guard. It would be unconscionable if a lack of preparedness resulted in hundreds of unnecessary cases of Zika and potential congenital abnormalities in newborns.”