The coronavirus, known as COVID-19, began in China and has spread in Asia, the Middle East, and Europe, with 57 confirmed cases in the US.

Cities are gearing up to address the potential spread of the virus. The mayor of San Francisco just declared a state of emergency in the city to prepare for a potential coronavirus outbreak.

The WHO has yet to call the virus a pandemic, but it did say it has "pandemic potential." The CDC has its own recommendations to prepare a household in case of pandemic disease, which includes utilizing a separate bedroom in the event that members fall ill.

But in San Francisco's crowded and expensive real estate market, most residents are renters who don't have the luxury of a second bedroom.

The San Francisco residents that are able to follow the CDC's guidelines are those that can afford a home with at least two bedrooms.

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As the coronavirus, known as COVID-19, continues to spread and concerns regarding the virus grow, US cities are gearing up to address the potential exposure.

There are 57 confirmed cases in the US, with 80,000 having been infected and 2,700 people having died from the virus worldwide. There haven't been any confirmed cases of COVID-19 in San Francisco so far, but Mayor London Breed of San Francisco said the city needs to be prepared in case the virus starts to spread.

Breed just declared a state of emergency in the city over coronavirus concerns as other cities have issued similar emergencies.

"The global picture is changing rapidly, and we need to step-up preparedness," Breed said in a statement. "We see the virus spreading in new parts of the world every day, and we are taking the necessary steps to protect San Franciscans from harm."

Declaring a state of emergency allows the city to allocate resources and funds in case of a coronavirus outbreak in San Francisco. There are, of course, best practices everyone can take to further prevent the spread of the virus, like washing your hands.

The World Health Organization has yet to call the outbreak a pandemic, a designation given when a disease spreads worldwide. But the WHO did say the virus has "pandemic potential."

The Centers for Disease Control and Prevention (CDC) has its own guidelines on how to prepare in case of a pandemic disease. One of the steps included in the CDC's recommendations is how to prepare if some household members become ill. The CDC advises using a separate bedroom in your home to separate the sick relatives from the healthy ones.

"Use the separate room and bathroom you prepared for sick household members," reads the guidelines for preparing your emergency plan.

But in San Francisco's crowded housing market, that may be a bit of an issue.

Other dense cities in the US face a similar predicament, but San Francisco's housing shortage is felt acutely. Housing units are limited, and on top of that, space in those homes is tight, with many having been built at a time when the city's population was much lower. Almost half of the city's housing units were built before 1940.

Having an extra bedroom isn't a luxury for many residents in the city, where space is a premium and housing costs are subsequently sky-high.