A medical staffer on France's TGV train on March 29.
  • The coronavirus has sickened more than 2 million people and killed over 143,000 around the world.
  • A third of the world is under some form of lockdown.
  • The US has the largest reported outbreak, representing about 30% of the world's Covid-19 cases.
  • Here's everything we know about Covid-19.
  • For mores stories go to www.BusinessInsider.co.za.

As the coronavirus pandemic continues to grow and evolve - more than 2.1 million people have been infected and 143,800 have died - researchers are scrambling to learn about the virus and recommend effective responses.

Although outbreaks are still growing rapidly in many countries and researchers' understanding of the virus is changing, a consensus is evolving about some key aspects of the virus' spread, symptoms, and deadliness.

Typical coronavirus patients develop a fever, dry cough, or shortness of breath, but these symptoms may appear at different times - or not at all.

The virus' average incubation period is about five days, but can range anywhere from two to 14 days, according to the CDC. It's likely that people can transmit the virus during this time - research shows the average infected person spreads the virus to about 2.2 others.

To limit that spread, many governments have declared nationwide lockdowns or otherwise dramatically restricted travel, affecting hundreds of millions of people. A third of the world is under some form of lockdown.

DataTicker - Covid 19 Global and US

Here are 26 crucial questions about the coronavirus, and what we know so far.

Where has the coronavirus spread?

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The coronavirus has spread to nearly all of the world's countries and territories.

At least 185 countries and territories had reported Covid-19 cases as of April 16, according to a database from Johns Hopkins University.

The US, much of Western Europe, and China have reported the largest outbreaks.

Where is the epicenter of the pandemic? Which country has the largest outbreak?

The US has the world's highest case total by far, and the state of New York is the epicenter of its outbreak.

As many as 100,000 to 240,000 people could die of the coronavirus in the US, even with shutdowns and stay-at-home orders, the White House's coronavirus task force warned on March 31. Without any social distancing or mitigation efforts, between 1.5 and 2.2 million Americans could die, according to modeling.

All 50 US states and Washington, DC, have reported coronavirus cases. Infections have also been confirmed in the US Virgin Islands, Guam, and Puerto Rico.

The state of New York had 10% of all reported Covid-19 cases in the world as of April 16. The US overall has reported 30% of the world's cases.

How long will Americans have to practice social distancing?

Nationwide social distancing guidelines last through at least April 30, but legal orders vary by state.

At a White House press briefing on March 29, President Donald Trump announced that social distancing recommendations in the US will remain in effect through April 30.

But stay-at-home and shelter-in-place orders vary across states, and some don't even have them.

It's unclear what will happen after April. Some experts have suggested that cities and states should open things up slowly, test widely to track the virus's spread, and impose lockdowns again before new waves of infection grow too large.

How many people are under lockdown worldwide?

David Ramos/Getty Images

A third of the world's population is under some sort of travel restriction.

India put its 1.3 billion residents under a 21-day nationwide lockdown on March 24, effectively doubling the number of people under restrictions worldwide.

Since then, at least a third of the world's population has been under some sort of restriction. That's more people than were alive during WWII.

"Lockdown" isn't a technical term but can include mandatory geographic quarantines, closings of certain types of businesses, and bans on events and gatherings.

Many countries have also shut their borders, and the Trump administration has issued the highest possible travel warning for every country.

How have lockdowns affected schools and children?


A running UNESCO tally says 191 countries had shut down their schools as of April 16.

The closings have disrupted the education of over 1.5 billion students - more than 91% of the enrolled learners in the world.

What's the best way to prevent the spread of Covid-19?

Joey Hadden/Business Insider

To prevent the spread of the coronavirus, people should wash their hands frequently, wear masks, and practice social distancing.

The WHO, US CDC, and multiple other national health agencies all agree on the importance of handwashing. People should wash their hands frequently with soap and water, making sure to scrub for at least 20 seconds.

People should also avoid touching their eyes, nose, or mouth with unwashed hands.

The CDC and other authorities recommend social distancing to slow the virus's spread and prevent the influx of cases from overwhelming hospitals.

Social distancing, according to Johns Hopkins, consists of "deliberately increasing the physical space between people to avoid spreading illness," which includes staying at least 6 feet (2 metres) away from other people, canceling events, and working from home if possible.

How contagious is the coronavirus?

An average coronavirus patient infects at least 2 others.

That's based on a crucial measure called R0 (pronounced R-naught), which refers to the average number of people that one sick person goes on to infect.

The R0 for the coronavirus currently sits around 2 to 2.5, meaning that each infected person spreads the virus to an average of 2.2 others. That means it's more contagious than the seasonal flu, but less contagious than measles.

"It is a virus that is quite good at transmitting from one person to another," Anthony Fauci said in a February interview hosted by the Journal of the American Medical Association.

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