There has been some confusion that COVID-19 is the 19th coronavirus disease, but the 19 refers to the year the new virus jumped to humans, 2019. In fact, "of the millions, perhaps billions, of coronaviruses, six were previously known to infect humans," The Washington Post reports.
Four cause colds that spread easily each winter, barely noticed. Another was responsible for the outbreak of severe acute respiratory syndrome that killed 774 people in 2003. Yet another sparked the outbreak of Middle East respiratory syndrome in 2012, which kills 34 percent of the people who contract it. But few do. SARS-CoV-2, the bad seed of the coronavirus family, is the seventh. It has managed to combine the infectiousness of its cold-causing cousins with some of the lethality of SARS and MERS. [The Washington Post]
"This is a virus that literally did not exist in humans six months ago," Geoffrey Barnes, an assistant professor at the University of Michigan, told the Post. "We had to rapidly learn how this virus impacts the human body and identify ways to treat it literally in a time-scale of weeks."
But scientists do know that coronaviruses invade the body by breaking into ACE2 receptors, which regulate blood pressure and are plentiful in the lungs, intestines, and kidneys. And they suspect the "corona" — or spikes on the outside of the virus — in the COVID-19 virus are more effective at attaching to the receptors, making it easier for them to infiltrate the cells to replicate, as the Post explains in this video.
The coronavirus hijacking your cells "would be as if somebody walked into a car factory and snapped his fingers and said suddenly, 'You're making Twinkies!'" David Leib, chair of microbiology and immunology at Dartmouth College, told WGBH. "It takes the virus roughly 10 minutes to get inside that cell and then to begin its replication cycle," and within days "you are a walking bottle of virus."
The coronavirus had infected at least 4.1 million people around the world by early Monday, including 1.3 million in the U.S., and officially killed 282,727 people, including 79,528 in the U.S., according to Johns Hopkins University's tally.