Much is left to learn about the coronavirus that is changing life as we know it, but our journey has already yielded many lessons. In late December 2019, reports emerged of a novel coronavirus outbreak connected with pneumonia cases at a wildlife market in Wuhan, China. COVID-19 spread across the nation within weeks—and then stormed its way across the world. By March 11, the World Health Organization labeled COVID-19 a pandemic.
In the time since, we’ve learned some important basics about SARS-CoV-2, the novel coronavirus behind COVID-19—including how it spreads then invades the body and which parts of the world are currently facing serious outbreaks. Here are maps that illustrate its spread and answers to other key questions about COVID-19.
How many cases are there worldwide?
The coronavirus pandemic is reshaping the world. Here’s a closer look at the case counts and fatalities across the world.
Where are cases growing and declining in the U.S.?
The coronavirus is affecting U.S. regions in different ways. Here are the areas where cases and deaths are either decreasing or increasing the most, based on the last seven days compared to the previous week.
What is a coronavirus?
Coronaviruses are a large family of viruses, but only seven of its members infect humans. Four types cause minor illnesses like the common cold, while other coronaviruses have triggered far more devastating impacts such as SARS, MERS, and now COVID-19. Coronaviruses can be zoonotic, meaning they jump from animals to humans.
Like its relatives, COVID-19 is primarily a respiratory disease that starts in the lungs, causing pneumonia-like symptoms, but can also cast a storm across the entire body.
How does COVID-19 spread?
Like other respiratory diseases, COVID-19 primarily spreads through small droplets—saliva or mucus—that an infected person expels when they cough, sneeze, or talk. These droplets can travel three to six feet and remain infectious for anywhere from four to 48 hours, depending on the surface. (The virus may also spread via accidental consumption of fecal matter or aerosols, tiny particles that are mostly a concern in clinical settings.)
You can protect yourself from catching the virus by staying six feet away from others and washing your hands with soap and water for more than 20 seconds.
How long does it last on surfaces?
The virus lives longer on surfaces. Disinfectants that are at least 60 percent alcohol by volume can also kill the virus on plastic and stainless steel surfaces.
What does the coronavirus look like?
Coronaviruses get their name from their spiky structure. Like other coronaviruses, SARS-CoV-2 is spherical with spike proteins that look a bit like a corona, or crown.
How does SARS-CoV-2 invade the body?
Its spiky structure helps the coronavirus latch onto cells that it can invade. Once a virus enters the human body through the eyes, mouth, or nose, it looks for cells with its favorite doorways—proteins called receptors. If the virus finds a compatible receptor, it can invade and start replicating itself. For SARS-CoV-2, that receptor is found in lung cells and the gut.
How does age factor into the severity of the disease?
Currently, children with COVID-19 may be less likely to require intensive care and also have lower fatality rates than adults. The difference in severity is not yet fully understood.
What are the common diagnostic symptoms?
There isn’t a single diagnostic symptom, but some are more common:
What are the chronic conditions that put people at higher risk?
COVID-19 poses a particularly serious threat to people with underlying conditions such as cardiovascular disease, diabetes, chronic lung disease, high blood pressure, and cancer.
How do you diagnose the virus?
Testing is done to diagnose the presence of the virus. Swab samples taken from the nose or mouth are tested for the virus’s genetic material. Researchers are also developing protocols for tests using saliva and blood samples.
When will a vaccine be ready?
To develop immunity, vaccines may contain killed or weakened virus, viral proteins, or viral genetic material. The best strategy to use against SARS-CoV-2 is yet to be determined. It could take until January 2021—or perhaps much longer—before a vaccine is ready for public use.
See all of National Geographic's coronavirus coverage.