'Complete saturation': Italian hospital is receiving a new coronavirus patient every 5 minutes

With the bulk of Italy's residents on coronavirus lockdown, a top infectious disease expert cautioned Thursday that the country is likely still two weeks away from seeing the deadly disease reach its peak.

Dr. Massimo Galli, head of the infectious disease unit at the overwhelmed Sacco Hospital in Milan, told ABC News that the hospital is receiving new patients every five minutes and that the facility is reaching a point of "complete saturation."

"I think patients will increase for another week or two," Galli said, adding that the country could see infections spread for up to four more weeks.

While new patients are being admitted to the Sacco Hospital, one of the largest medical centers in Italy, every five minutes, Galli said virus-free patients are being discharged every two or three hours.

"We are getting close to not being able to accept new patients. There is a complete saturation of beds," Galli said, adding that hospital administrators are seeking alternative buildings to treat patients.

On Wednesday, the World Health Organization declared the virus a global pandemic as more than 120,000 people worldwide have tested positive for the virus.

Italian officials say the number of people with confirmed cases of coronavirus, officially referred to as COVID-19, is at least 12,462 with more than 1,016 deaths as of Thursday afternoon. The country is the hardest hit in Europe and second only to China in the number of coronavirus cases.

On Monday, Italian Prime Minister Guiseppe Conte took the dramatic step of instituting the lockdown of millions of residents, particularly those in the Lombardy region, which includes Milan.

Conte asked all residents to avoid traveling beyond the areas where they live, and he required all businesses, with the exception of pharmacies and grocery stores, to shut down. The decree also required all schools to close.

"In Italy, we have to limit social contacts," Galli told ABC News. "In this way we are confident to limit further spread of the infection."

He said other countries, including the United States, should remain "extremely alert" in tracking all infected people.

"This is a really serious infection. I don't want to contemplate Africa. In this situation we are forever unprepared. It is impossible to have enough beds," he said.

Galli said a team of scientists in Milan have matched the Italian genetic sequencing of the virus to a sequence found in Munich, Germany, and believe that the virus made its way to Italy from China via Munich in late January.

"In our opinion, the origin is from a small outbreak that happened in January with contact with women who came from China to meetings in Munich. Our sequences match those found in Munich," Galli said. "It is probably [that] the virus arrived from Munich in a triangle of traveling not directly from China. They were probably not aware."

Galli added that the United States could also see the virus spread rapidly unless major steps are taken to slow it down. U.S. officials across the country have moved in recent days to cancel events that attract large gatherings, including upcoming parades and sporting events. The National Basketball Association announced on Wednesday that it is suspending its season indefinitely, and the National Hockey League followed suit on Thursday.

"It's clear we have a pandemic," Galli said. "The numbers in Spain, France, Germany makes it look like they are just a few weeks from an epidemic. I hope I am wrong for everybody."

He warned that there a possibility the virus could spread undetected in California and New York as it has in Italy.

"Everybody should be extremely aware," he said. "Our experience is a terrible one."

What to know about the coronavirus

• Coronavirus explained : How it started and how to protect yourself
• Coronavirus symptoms: What to do if you have symptoms
• Coronavirus map: Track the spread in the U.S. and worldwide