Coronaviruses are a family of viruses that cause illness in animals and humans. They can cause upper respiratory tract infections in humans, with symptoms and complications ranging from mild to severe.
Most species of coronavirus do not affect humans. So far, seven coronaviruses have caused illness in humans — including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 19 (COVID-19).
In this article, we explore what coronaviruses are and how different types affect humans.
All data and statistics are based on publicly available data at the time of publication. Some information may be out of date.
Coronaviruses are a large family of viruses that
The name “coronavirus” comes from the crown-like spikes that cover the surfaces of the viruses in this family. Coronam is Latin for “crown.”
Most coronaviruses affect animals, such as bats and pigs.
Among all the coronaviruses, seven have affected humans. Four of these are common and cause mild illnesses in the upper and lower airways, nose, sinuses, throat, and lungs.
The remaining three can cause more severe illness. They are:
- severe acute respiratory syndrome coronavirus (SARS-CoV), which led to the SARS epidemic in 2002–2003
- Middle East respiratory syndrome coronavirus (MERS-CoV), which caused an outbreak of MERS that began in 2012
- SARS-CoV-2, the virus responsible for the COVID-19 pandemic
Common human coronaviruses
These four coronaviruses
These viruses are common worldwide and account for around
This virus causes severe acute respiratory syndrome, or SARS. The first cases of this disease in humans occurred in the Guangdong province of China in
In total, SARS spread across 26 countries, causing an epidemic with more than 8,000 cases. Since 2004, there have been no recorded cases of SARS in humans.
The symptoms of SARS include:
In severe cases, SARS causes a lack of oxygen in the blood, leading to death in 10% of people.
A 2019 report from the World Health Organization (WHO) suggests that MERS-CoV may spread through contact with animals, particularly camels. Human-to-human transmission is also possible during close contact with people who are sick. Healthcare workers, for example, may be particularly vulnerable.
- a fever
- a cough
- shortness of breath
Since 2012, most cases of MERS have occurred in the Middle East. There have been
No vaccines or drugs can treat or prevent MERS, and health authorities continue to monitor the virus closely.
SARS-CoV-2 is the virus that causes COVID-19. The first cases of COVID-19 were identified in the city of Wuhan, China, in 2019.
The illness can cause mild to severe symptoms. People with underlying medical conditions and older adults are most at risk of severe COVID-19.
- a fever
- a cough
- difficulty breathing
- body aches
- a new loss of taste or smell
- a sore throat
- nausea and vomiting
Not everyone with COVID-19 develops all of these symptoms — a person may only have one or two. Also, some people with the disease experience very mild symptoms, while others experience none at all.
Doctors are still learning the best ways to treat COVID-19. Meanwhile, the European Medicine Agency has endorsed the use of dexamethasone for people who need oxygen or ventilation and the
Major multinational efforts are
Coronaviruses reach humans through contact with animals. This includes animals such as livestock, including camels, and others, such as bats and cats.
Occasionally, one of these coronaviruses evolves the ability to infect humans.
Coronaviruses and influenza, or flu, viruses can both cause upper respiratory tract infections, and both can spread through close contact.
They also tend to cause similar symptoms, including a cough, a fever, and tiredness.
However, there are some important differences between flu viruses and the newest coronavirus to infect humans, SARS-CoV-2.
SARS-CoV-2 has a
However, the flu is more likely to cause complications in children, while COVID-19 generally appears to have less severe effects in children than in adults.
Until scientists develop vaccines for coronaviruses such as SARS-CoV-2, the most effective way to prevent transmission is so to follow official guidelines about physical distancing and hygiene.
According to the Centers for Disease Control and Prevention (CDC), the best ways to avoid the novel coronavirus involve:
Wash the hands often, for at least
- after visiting a public place
- after coughing, blowing the nose, or sneezing
- before preparing or eating food
- after using the bathroom or changing a diaper
- after handling a face mask
- after taking care of someone who is unwell
- after touching animals or pets
If soap and water are not available, use alcohol-based hand sanitizer, which should contain at least 60% alcohol.
Wear a mask that covers the nose and mouth in public and when socializing with people outside the household.
Household and personal hygiene
First, clean the surfaces with soap and water. Then, use a household disinfectant.
Another key element of hygiene involves covering coughs and sneezes with the inside of the elbow, rather than the hands, and avoiding touching the face unnecessarily.
Anyone who may have symptoms of COVID-19 should stay home and call a doctor. Do not visit a medical facility in person or spend any time in public areas.
To any extent possible, stay away from other household members and pets, and wear a mask, even at home.
Call 911 or otherwise contact emergency services if any of the following occur:
- trouble breathing
- persistent pain or pressure in the chest
- a seeming inability to wake up or stay awake
- a bluish tinge to the lips or face
Let the emergency services staff know before they arrive that COVID-19 is a possible cause of the symptoms, so they can take proper precautions.
Seven viruses in the coronavirus family infect humans. Most cause mild respiratory infections, such as the common cold. Three of these viruses cause more severe illness, and one example is SARS-CoV-2, which causes COVID-19.
There are currently no proven treatments for COVID-19, but health authorities and researchers are working hard to find viable options.