Alabama officials announced the state’s first case of COVID-19 Friday morning. That number jumped to six by the end of the day, and then doubled on Saturday.

“You saw all the people partying this weekend for St. Patrick’s Day,” said Dr. Jeanne Marrazzo, director of the division of infectious diseases at the University of Alabama at Birmingham. “I’m happy for them but I’m very sorry for us. We all have to give a little to keep us safe.”

Some testing labs closed on Sunday, but the cases continued to mount. By Tuesday morning, the number of confirmed cases stood at 36 – a small number overall, but a huge jump from just four days earlier.

“We will see a doubling at least every other day,” Marrazzo said. “We are assuming that trajectory will continue. And if you compare that to where Italy was a few weeks ago, it’s not pretty. I’m not an alarmist. I’ve been very calm about this.”

The jump triggered drastic action in Jefferson County, which has the majority of the state’s detected cases. Jefferson County Health Officer Dr. Mark Wilson issued an order closing bars and restaurants for a week, daycares and preschools until April 6, closing senior centers, banning large gatherings and ending most nursing home visits. On Tuesday morning, State Health Officer Dr. Scott Harris expanded that order to the counties surrounding Birmingham: Blount, St. Clair, Shelby, Tuscaloosa and Walker.

Without the changes, experts warn the spread of COVID-19 could get much worse and even overwhelm the medical system. Marrazzo said the growth could continue for the foreseeable future.

The only way to stop the deadly snowball is to encourage, and even enforce, social distancing. The coronavirus is now spreading in the community, Wilson said. But it can be slowed if people dramatically limit contact with one another – maintaining six feet of distance in group settings and staying home as much as possible.

That, along with vigilant hand washing, could limit the outbreak, Marrazzo said.

“If we do not take this seriously and really pay attention to the social distancing measures, we will not have a chance to change the trajectory of what Italy is experiencing,” Marrazzo said.

That is the reasoning behind closing Jefferson County’s bars and restaurants, Wilson said.

“I want to stress the importance of us taking this very seriously, Wilson said. “The number of cases is expected to double every two days if we do not take swift and very deliberate action and stop the spread and give our public health partners time to get this under control.”

Italy now has nearly 30,000 cases of coronavirus, many of them severe. The influx of patients has swamped hospitals in the northern part of the country, forcing doctors to ration access to lifesaving equipment.

If the number of cases in Alabama continues to double every day or two, doctors here could face similar choices, Marrazzo said.

The disease is particularly hard on elderly patients and those with preexisting conditions. The fatality rates increase significantly among people older than 60. Limiting social contact offers protection for these patients by slowing the spread of germs.

Experts have been urging social distancing for weeks, but it’s unclear whether the message is getting through. Measures like closing schools and restaurants negatively affect families and workers – making them unpopular even as medical experts claim they are necessary. Video from the weekend showed large crowds thronging the streets of New Orleans and Miami.

Officials have also struggled to gauge the proper response due to testing delays. Labs didn’t test any samples in Alabama until March 5 and many are still woefully behind schedule. Marrazzo fears that many people with COVID-19 have already unknowingly passed it to others, which makes the illness harder to contain.

“Honestly, the numbers that we have, to say they are the tip of the iceberg is the understatement of the century,” Marrazzo said.

But even with the bad news out of Italy, Marrazzo points to one bright spot in the fight against coronavirus. Officials in the region of Lodi put strong restrictions in place soon after the first cases appeared, preventing the type of outbreak that paralyzed Bergamo.

There is some good news for Alabama. An outbreak could spare rural parts of the state where the physical distance between residents often keeps them apart naturally, Marrazzo said. But Alabamians also suffer from high rates of underlying illness that could make them vulnerable to complications from the virus.

Brian Hastings is the director of the Alabama Emergency Management Agency. He said people should stay calm and avoid large crowds.

“This is no time for fear, it is time for respect and believing you have a purpose in protecting the people around you,” Hastings said.

In addition to public actions, private businesses have also taken steps to keep employees at home. And UAB medicine is urging patients with non-emergency needs to use telehealth and online services as much as possible.

Wilson said people can support the local economy, and workers, even during the shutdown.

“Keep calm and order carryout,” Wilson said.

Here are our live updates on the public health crisis in Alabama. You can find all of our coronavirus stories here.