On Jan. 19, 2020, CNET posted its first guide about a mystery coronavirus discovered in the central Chinese city of Wuhan. Dozens of cases and two deaths had been recorded but, as we wrote at the time, little was known about "how destructive the new virus might be." The coronavirus — and the disease it causes — hadn't even been named. It hadn't even officially been found in the US.
Today we call the mystery pathogen SARS-CoV-2. It's responsible for COVID-19, a respiratory illness that has infected over 100 million people. In just one year, we've gone from two deaths to 2 million, across the world.
Reading our original article, it's immediately obvious that everyone — virologists, epidemiologists, journalists — was flying blind in those very early days. We were oblivious, perhaps even shortsighted. No one predicted exactly what would occur over the next 365 days, though there were those who tried to sound the alarm early.
Back then, research had only just begun to uncover how we might combat COVID-19. In those early days, new data came quickly, but there were significant gaps in our knowledge that allowed a deluge of misinformation, conspiracy and fear to fester.
We attempted to answer six questions on Jan. 19, 2020. They were fundamental questions about the new virus, its symptoms and how it spread. A year on, we are revisiting them. This updated guide reveals how much we've learned and charts how science was able to provide certainty and hope in the face of the biggest public health crisis in a century.
Science and technology have provided clarity where there was none — but much remains unknown as we face the second pandemic year.
What is a coronavirus?
There is no better-known virus on Earth than the coronavirus, SARS-CoV-2, which was first detected in Wuhan in December 2019. In a landslide victory, the coronavirus beats out Ebola, influenza, HIV and the panoply of viruses that cause the common cold for Earth's Most Renowned Virus. But it's not the only coronavirus.
Coronaviruses belong to a taxonomic family known as Coronaviridae, which includes dozens of different species. First described in 1968, coronaviruses are shaped like soccer balls wrapped in a blanket of spikes. Under an electron microscope, these spikes look like the sun's corona — hence their name. Only a handful are known to cause disease in humans.
The SARS epidemic of 2002-03 and the MERS epidemic of 2012 showed coronaviruses have the capability to cause significant outbreaks of the deadly disease. The epidemics launched an international effort to understand the pandemic potential of coronaviruses.
In 2020, 65,000 papers were published and listed on PubMed under the term "coronavirus." A year prior, that number was 885. The lessons we're learning about SARS-CoV-2 are relevant to this particular virus but also revealing more and more about coronaviruses in general. "It is the fastest-moving field I have ever seen in my life," says Stuart Turville, an immune virologist at the Kirby Institute in Australia.
Among the defining characteristics of the coronavirus are the numerous "spikes" on its surface. These proteins function like keys, allowing a coronavirus to enter a cell. Spikes are able to unlock entry by binding to a "lock," a cell surface protein in humans (and other animals) known as ACE2. The two pieces of molecular machinery have been the focus of thousands of researchers around the world since January 2020.
During the SARS epidemic, scientists had learned that the spike elicits an immune response, stimulating cells and antibodies to fight the virus. This gave them a headstart on building vaccines against SARS-CoV-2. "Labs could download the [genetic] sequence of the spike protein and start developing vaccines as soon as the scientists in China had sequenced it," says Larisa Labzin, an immunologist at the University of Queensland, Australia. By the end of 2020, several vaccines had already been rolled out.
But the spike in SARS-CoV-2 appears to be changing.
We're seeing new variants of the virus emerge across the world, with slight changes to the spike proteins. Scientists are watching these changes occur in real time by analyzing the genome of virus samples faster than ever before. We don't yet understand a lot about why they are changing. The virus is evolving in a way that may help it evade our immune system, and similar variants seem to be cropping up across the globe — a development that may affect vaccines.