Health
A group of coronavirus virions
A group of coronavirus virions
A group of coronavirus virions

What Is Coronavirus?

Updated on July 29, 2022

Coronaviruses are a type of virus. There are many different kinds, and some cause disease. A coronavirus identified in 2019, SARS-CoV-2, has caused a pandemic of respiratory illness, called COVID-19.

What You Need to Know COVID-19

  • COVID-19 is the disease caused by SARS-CoV-2, the coronavirus that emerged in December 2019.
  • COVID-19 can be severe, and has caused millions of deaths around the world as well as lasting health problems in some who have survived the illness.
  • The coronavirus can be spread from person to person. It is diagnosed with a test.
  • The best way to protect yourself is to get vaccinated and boosted when you are eligible, follow testing guidelines, wear a mask, wash your hands and practice physical distancing.

How does the coronavirus spread?

As of now, researchers know that the coronavirus is spread through droplets and virus particles released into the air when an infected person breathes, talks, laughs, sings, coughs or sneezes. Larger droplets may fall to the ground in a few seconds, but tiny infectious particles can linger in the air and accumulate in indoor places, especially where many people are gathered and there is poor ventilation. This is why mask-wearing, hand hygiene and physical distancing are essential to preventing COVID-19.

How did the coronavirus start?

The first case of COVID-19 was reported Dec. 1, 2019, and the cause was a then-new coronavirus later named SARS-CoV-2. SARS-CoV-2 may have originated in an animal and changed (mutated) so it could cause illness in humans. In the past, several infectious disease outbreaks have been traced to viruses originating in birds, pigs, bats and other animals that mutated to become dangerous to humans. Research continues, and more study may reveal how and why the coronavirus evolved to cause pandemic disease.

What is the incubation period for COVID-19?

Symptoms show up in people within two to 14 days of exposure to the virus. A person infected with the coronavirus is contagious to others for up to two days before symptoms appear, and they remain contagious to others for 10 to 20 days, depending upon their immune system and the severity of their illness. 

What have you learned about coronavirus in the last six months?

Infectious disease expert Lisa Maragakis explains the advances in COVID-19 treatments and how knowledge of COVID-19 can assist in preventing further spread of the virus.

What are symptoms of coronavirus?

COVID-19 symptoms include:

  • Cough
  • Fever or chills
  • Shortness of breath or difficulty breathing
  • Muscle or body aches
  • Sore throat
  • New loss of taste or smell
  • Diarrhea
  • Headache
  • New fatigue
  • Nausea or vomiting
  • Congestion or runny nose

Some people infected with the coronavirus have mild COVID-19 illness, and others have no symptoms at all. In some cases, however, COVID-19 can lead to respiratory failure, lasting lung and heart muscle damagenervous system problemskidney failure or death.

If you have a fever or any of the symptoms listed above, call your doctor or a health care provider and explain your symptoms over the phone before going to the doctor’s office, urgent care facility or emergency room. Here are suggestions if you feel sick and are concerned you might have COVID-19.

CALL 911 if you have a medical emergency such as severe shortness of breath or difficulty breathing.

Learn more about COVID-19 symptoms.

What Is Coronavirus?

How is COVID-19 diagnosed?

COVID-19 is diagnosed through a test. Diagnosis by examination alone is difficult since many COVID-19 signs and symptoms can be caused by other illnesses. Some people with the coronavirus do not have symptoms at all. Learn more about COVID-19 testing.

How is COVID-19 treated?

Treatment for COVID-19 depends on the severity of the infection. For milder illness, resting at home and taking medicine to reduce fever is often sufficient. More severe cases may require hospitalization, with treatment that might include intravenous medications, supplemental oxygen, assisted ventilation and other supportive measures

How do you protect yourself from this?

There are several COVID-19 vaccines recommended by the CDC. It is also important to receive a booster when you are eligible.

In addition, it helps to keep up with other safety precautions, such as following testing guidelines, wearing a mask, washing your hands and practicing physical distancing.

Does COVID-19 cause death?

Yes, severe COVID-19 can be fatal. For updates of coronavirus infections, deaths and vaccinations worldwide, see the Coronavirus COVID-19 Global Cases map developed by the Johns Hopkins Center for Systems Science and Engineering.

Two COVID-19 vaccines – Pfizer and Moderna - have been fully approved by the FDA and recommended by the CDC as highly effective in preventing serious disease, hospitalization and death from COVID-19.

The CDC notes that in most situations the two mRNA vaccines from Pfizer and Moderna are preferred over the Johnson & Johnson vaccine due to a risk of serious adverse events.

It is also important to receive a booster when eligible. You can get any of these three authorized or approved vaccines, but the CDC explains that Pfizer and Moderna are preferred in most situations.

Why is it called coronavirus?

Coronaviruses are named for their appearance: “corona” means “crown.” The virus’s outer layers are covered with spike proteins that surround them like a crown.

Is this coronavirus different from SARS?

SARS stands for severe acute respiratory syndrome. In 2003, an outbreak of SARS affected people in several countries before ending in 2004. The coronavirus that causes COVID-19 is similar to the one that caused the 2003 SARS outbreak.

Since the 2019 coronavirus is related to the original coronavirus that caused SARS and can also cause severe acute respiratory syndrome, there is “SARS” in its name: SARS-CoV-2. Much is still unknown about these viruses, but SARS-CoV-2 spreads faster and farther than the 2003 SARS-CoV-1 virus. This is likely because of how easily it is transmitted person to person, even from asymptomatic carriers of the virus.

Are there different variants of this coronavirus?

Yes, there are different variants of this coronavirus. Like other viruses, the coronavirus that causes COVID-19 can change (mutate). Mutations may enable the coronavirus to spread faster from person to person as in the case of the delta and omicron variants. More infections can result in more people getting very sick and also create more opportunity for the virus to develop further mutations. Read more about coronavirus variants.

Coronavirus: What do I do if I Feel Sick?

If you are concerned that you may have COVID-19, follow these steps to help protect your health and the health of others.

About Coronaviruses

  • Coronaviruses are common in different animals. Rarely, an animal coronavirus can infect humans.
  • There are many different kinds of coronaviruses. Some of them can cause colds or other mild respiratory (nose, throat, lung) illnesses.
  • Other coronaviruses can cause serious diseases, including severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).
Scientist carefully insets a pipette into a test tube.

Coronavirus (COVID-19)

What you need to know from Johns Hopkins Medicine.