Coronavirus Basics

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When a new virus first infects humans, there is serious potential risk. Which is exactly what has unfolded first in China and now, three weeks later, across the globe. So a few facts about Wuhan Coronavirus: what it is, why it could spread so fast, and what we can all do about it.

  • Coronavirus is a family of viruses that can cause a wide range of illnesses. Remember SARS, which triggered symptoms that accounted for its name (Sudden Acute Respiratory Syndrome)? SARS was caused by a coronavirus. But the common cold is also caused by a coronavirus – in fact, several different strains can cause colds that manifest differently from person to person.

  • The new strain of coronavirus that’s all over the news was first reported at the end of December in Wuhan, China. The initial cases were seen in people who had visited a seafood and livestock market, so public health officials were not sure that it could – or ever would – spread from person to person. But on January 13, the virus was found in Thailand, evidence of human-to-human transmission. Here’s a timeline that outlines where the virus started and how it has moved. And here’s a map.

  • This week the strain of coronavirus was identified in a man in Washington state. As soon as he was diagnosed, the U.S. implemented mandatory screening of passengers coming to the U.S. from Wuhan at several airports. The list currently includes: Los Angeles, San Francisco, New York (JFK), Atlanta, and Chicago. On January 24, a second US case was identified in Chicago.

  • In an unprecedented move, on January 22 China locked down Wuhan, halting all in- and outbound trains, planes, buses and subways. Hoping to limit further spread, the step was taken in an attempt to quarantine the 11 million residents of the city as travel for Chinese New Year kicks off. Over the next few days, surrounding cities were named in order to broaden the quarantine. The situation and public health response are rapidly evolving, but as of publication time, the restricted travel zones impact 35 million Chinese people.

  • Why all the mayhem? Because in the three-and-a-half weeks since this all started, more than 800 people have been diagnosed with the new coronavirus strain and at least 40 have died. Both of these numbers are conservative estimates. The 800 infected, for instance, are 800 who have tested positive. Researchers estimate that the actual number is almost certainly in the thousands.

  • And why is this happening in the first place? Our immune systems have memory, which means that once we have been infected with a particular bacteria or virus, we generally remember and therefore respond – immunologically – very quickly. As a result, the infection doesn’t have a chance to multiply or unleash its impact on our bodies. The very first time we are exposed to a given infection, though, our immune system is naïve and needs to take some time – usually a day or two, sometimes longer – to mount its response. During this time, we are also quite contagious, spreading the infection easily (depending upon the type of infection, but it’s a fair generalization). So, with this new strain of viris, basically no humans have any immune memory for it – anyone who is exposed and infected will need to engage their immune system and mount a response. This takes time, increases contagiousness, and can be life-threatening if the infection wreaks havoc before the immune system catches up.

  • One last note: you’ll probably hear comparisons between the Wuhan strain of coronavirus and other strains, like SARS and MERS. Here’s a nice chart comparing them all.