The coronavirus has sickened more than 2.5 million people and killed more than 179,000 around the world.

A third of the world is under some form of lockdown.

The US has the largest reported outbreak, representing about 32% of the world's COVID-19 cases.

Here's everything we know about COVID-19.

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As the coronavirus pandemic continues to grow and evolve — more than 2.5 million people have been infected and 179,000 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, and 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.

COVID-19 spread globally Confirmed Cases Deaths Global United States Last updated using data from JHU CSSE

Here are 32 crucial questions about the coronavirus, and what we know so far.