The CDC outlined an ominous hypothetical scenario about what could happen in the US as the coronavirus spreads. Here's what to expect.

The coronavirus will be difficult to stop from spreading, but cities and counties in the US are preparing for this.

As of Wednesday, San Francisco, Orange County, San Diego County, and Santa Clara County, had all declared health emergencies. This was done to make sure there was access to funding to prepare for a coronavirus outbreak.

According to the CDC, the coronavirus spreads between people in close contact, often through droplets excreted by coughing or sneezing. It can also be spread through touching objects that the virus is already on.

There are a number of symptoms to look out for. Business Insider's Aria Bendix explained that the first symptom is a fever — about 99% of patients in one study developed one. More than half of patients developed a dry cough and experienced fatigue. And about one-third of patients had sore muscles and breathing difficulties.

But unfortunately monitoring symptoms might not be enough. On Monday, Chinese researchers reported that a person can transmit the coronavirus without showing any symptoms. One woman from Wuhan transmitted the coronavrius to five family members, despite getting clear scans and never becoming ill herself.

One of the looming problems for the US trying to stop the coronavirus from spreading is that there aren't enough face masks for healthcare workers, according to Health and Human Services Secretary Alex Azar.

America currently has 30 million face masks, but it needs another 270 million, he said Tuesday.

The CDC doesn't recommend that uninfected people wear masks, but they're worthwhile for people who have coronavirus symptoms, and to protect healthcare workers from getting sick.

On Thursday, Japan's Prime Minister Shinzo Abe announced every school in Japan would close for at least a month, after there were 890 confirmed cases of the coronavirus. More than 700 of these had some connection to the Diamond Princess cruise ship.

In China, all schools are closed, until the coronavirus is no longer a public health emergency. About 180 million children in China are currently learning from home, taking classes online, or watching primary school classes broadcast on television.

Schools haven't closed in the US yet, but the CDC warned schools could be closed for extended periods of time if the disease keeps spreading.

Already, some US schooling districts have sent letters to students' families informing them to not send sick children to school, and reminding them about vaccinations and to wash their hands.

In early February, healthcare workers told Business Insider's Morgan-Johnson how hospitals were handling potential coronavirus cases. They were using isolation chambers, wearing face shields and other protective gear, and had infectious-disease experts on hand.

Doctors looked for two red flags — whether someone had been to China recently, and what symptoms they had, looking specifically for fevers, shortness of breath, and coughing.

Experts say people should call ahead if they think they have symptoms before going into the hospital. One Chicago-based flight nurse named Mia Martinez told Business Insider, "The scary part for me would be someone just kind of coming into an ER, especially with how crowded they are nowadays."

The coronavirus' impact on infrastructure has been notable in China. Beginning on January 23, Wuhan, a city of 11 million people, where the coronavirus was first discovered, has been on lockdown. Police closed entry points into the city, and have been patrolling the city's train stations.

Other than for several hours where the quarantine was briefly lifted before being reimposed, the quarantine has been constant. The mass quarantine escalated in early February, when the Chinese government put another 15 cities, with about 35 million people, on lockdown. It's the largest quarantine in human history.

Outside of Asia, Italy, which has become the epicenter of the coronavirus in Europe, has also been using its law enforcement to deal with the coronavirus.

In northern Italy, 11 quarantined towns are surrounded around the clock by military police, to try and stop the coronavirus from spreading.

Police have also been monitoring two resorts on lockdown in Europe — one hotel called the Costa Adeje Palace, with more than 450 rooms in Tenerife, Spain, which is on lockdown for two weeks, and another in a ski resort with 108 rooms in Innsbruck, Austria.

If quarantines are enacted in the US, they'd be under the jurisdiction of the CDC. The agency already screens passengers at airports and other ports of entry for diseases (and has been doing so for coronavirus), and could enforce isolation and quarantines throughout the country or in specific areas to prevent the spread of COVID-19.

This could mean that hospitals would shift priorities away from other health problems to focus on the coronavirus.

In China, this has already happened. In Wuhan, hospitals have devoted 19,000 beds to exclusively treating the coronavirus. One man who needed surgery for a tumor pressing on his spine was sent home from hospital, without his surgery, Time reported.

Another man's weekly dialysis sessions for kidney failure were canceled, because of the coronavirus.

But drug companies are doing their best to come up with a solution, either testing existing drugs to see whether they'll be effective, or by starting from scratch, using the coronavirus' genetic code.

One biotech drug company, called Moderna, has already provided US health officials with a possible vaccine, to begin testing — hopefully by mid-April.

After generating a firestorm of criticism over the possible high price of any new coronavirus vaccine if it's developed, the Trump administration reversed itself on Thursday and said it would guarantee public access to an affordable vaccine.

Business Insider's Hillary Hoffower pointed out that the largest healthcare costs from treating coronavirus would likely be from long hospital stays.

It's worth knowing that CDC is the only place that's currently testing for the coronavirus in the US and it's not charging patients for it, according to America's Health Insurance Plans.

AHIP also pointed out that health insurance providers cover "reasonable, medically necessary health care costs," which include the coronavirus. It recommended reviewing your specific plan.

These are actions that can be taken outside of medication and vaccinations.

The CDC recommends staying home when you're sick, washing you're hands, covering you're mouth when sneezing and coughing, and disinfecting surfaces (like door handles and refrigerators), and objects (like children's toys).

The CDC also recommends not getting too close to people when interacting with them.

For the patients who do go to the hospital, they're being treated for their symptoms. For example, hospitals can provide patients ibuprofen for pain, fluids if they have diarrhea, breathing support if the coronavirus causes pneumonia, and an intravenous drip if they have low blood pressure.

Public-health experts told Business Insider's Aylin Woodward it's possible "the new virus may never truly disappear." She wrote:

"There are only three possible endings to this coronavirus story: The outbreak could be controlled via public-health interventions and disappear (as SARS did), a vaccine could be developed, or the coronavirus could become a permanent part of the repertoire of human viruses, perhaps like the seasonal flu."