MINNEAPOLIS (WCCO) – Knowing there are cases of Ebola in the United States creates a sense of unease here in Minnesota.

Right now we’re Ebola-free, but not free from worrying.

“I don’t think it’s a joking matter, because if it comes here, I don’t know what we are going to do,” said a viewer on Nicollet Mall.

Part of the worry is that there’s no vaccine to turn to.

“In short, the only way we are ever going to stop this epidemic is a vaccine,” Dr. Michael Osterholm said .

Osterholm is the director for the Center of Infectious Disease at the University of Minnesota.

He said a vaccine has been in the works since the 1990s.

“And actually right now, there are a series of candidate vaccines that are being tested for possible use in West Africa,” Osterholm said.

So why weren’t these possible vaccines available earlier?

Osterholm said Ebola was so rare before this outbreak–just 2,000 cases since 1976–that many health officials felt it could be handled by isolation and quarantine.

“So no pharmaceutical company, no one decided to invest the millions it would take to make for a vaccine against Ebola,” Osterholm said.

Ebola’s rarity also made it hard for scientists to conduct field studies.

They need to test vaccines, pharmaceutical companies need to buy in, and then distribution can take place.

Osterholm said once a vaccine is approved, it’ll be here to stay.

“We are looking at the long haul here,” he said. “This isn’t going to be just another few months. We are in here for a while.”

Osterholm said the vaccine will be here to stay, because Ebola isn’t going anywhere.

He said the virus is carried by bats in Africa, and that won’t change.

The hope is a vaccine will be available sometime next year.