People following the news about SARS-CoV-2, the coronavirus that causes COVID-19, might think coronaviruses are a new disease. In fact, doctors first identified coronaviruses in the 1960s, and there are now seven known coronaviruses that vary in severity. All coronaviruses have the potential to cause respiratory illness—for some that could be as simple as the common cold, while others are much more serious. COVID-19, which was categorized as a pandemic in 2020, has sickened millions of people around the world and is causing a growing number of deaths. 

There are no cures for coronaviruses. So, as is the case whenever a new threat emerges, it’s important to follow specific public health recommendations. Doctors advise taking the same precautions you would to avoid a cold or flu, including meticulous handwashing and being cautious around people who are sick. Mitigation efforts to stop the spread of SARS-CoV-2 also have included the use of masks and social distancing (maintaining a 6-foot distance from other people).

Corona means crown in Latin; the name was chosen because when the virus is examined under a microscope, you can see spikes on its surface. The medical term coronavirus actually describes a family of viruses. Coronaviruses are common in both animals and humans, and in rare cases they have spread from animals to humans.

Scientists have identified several coronaviruses that affect humans, including 229E, NL63, HKU1, and OC43, which cause mild to moderate upper respiratory symptoms that can include cough, fever, headache, runny nose, and sore throat. (While all are symptoms of a common cold, it may be interesting to know that the common colds can be caused by coronaviruses, rhinoviruses, and other types of viruses.) 

The four coronaviruses named above also have the potential to lead to more serious conditions, such as bronchitis and pneumonia, especially in people who have weakened immune systems or are otherwise at high risk.

Three coronaviruses have caused serious symptoms and even death in humans:

• SARS, a deadly virus that sickened more than 8,000 people and led to almost 800 deaths before it was contained in 2003, causes body aches, chills, and fever, and usually led to pneumonia while it was circulating.
• Middle East Respiratory Syndrome (MERS), causes cough, fever, and shortness of breath, and also often leads to pneumonia. MERS initially surfaced in Saudi Arabia and continues to occur in that region.
• SARS-CoV-2 is the newest coronavirus, and health experts are still learning about how it causes COVID-19, which can lead to symptoms including cough, fever, and shortness of breath, and can cause pneumonia and even death in some cases. SARS-CoV-2 is the first coronavirus to be characterized by the World Health Organization (WHO) as a pandemic.

Coronaviruses are transmitted among people mostly through shaking hands or making other human contact; breathing the air where someone with a virus has sneezed and coughed; and touching exposed objects or surfaces and then touching the eyes, mouth, or other parts of the body. They are most likely to spread in the fall and winter, although you can get one at any time. Doctors are still learning about how SARS-CoV-2 is transmitted from one person to another.

All of us are at risk for coronaviruses, but for healthy people, the illnesses they cause may not be particularly dangerous. Older adults and people with chronic diseases such as heart disease and diabetes are considered to be at higher risk for more severe symptoms. 

If a coronavirus is circulating in a particular part of the world, it may be important to check the Centers for Disease Control and Prevention (CDC) travel advisories before planning trips. 

There is no treatment for most coronaviruses, and most people will recover on their own. However, anyone with serious symptoms should talk to their doctor. In most cases, symptoms can be relieved with over-the-counter medications, plenty of liquids and rest, and a humidifier if needed for a cough. In the case of COVID-19, the disease caused by of SARS-CoV-2, one treatment has been fully approved by the FDA, and a handful of others have received emergency use authorizations. But there is no single effective treatment, and researchers continue to study potential therapies. 

The CDC recommends taking the following precautions:

• Avoid people who are sick. This can be difficult in close quarters like elevators or subway cars but, when you can, try to maintain distance from anyone who is or appears to be ill. 
• Keep hands and fingers away from your face, because many respiratory viruses are transmitted when we touch contaminated surfaces and then touch our eyes and nose.
• Wash hands often with soap and water for at least 20 seconds, especially before touching your eyes and your nose. If soap and water are not available, use an alcohol-based hand sanitizer.
• If you cough or sneeze, cover your mouth, and if you use a tissue, throw it in the trash when you are finished and wash your hands. 
• Clean and disinfect objects and surfaces in your home, office, and car often. 
• The CDC recommends protecting against the SARS CoV-2 virus by practicing social distancing, staying at least 6 feet (about 2 arms’ length) from other people, and wearing a cloth face mask in public settings where other social distancing measures are difficult to maintain, especially in places where there is significant community transmission. 

While the symptoms can be similar, influenza is not a coronavirus, so a flu vaccine won’t prevent or reduce severity of coronaviruses. However, public health authorities strongly advise everyone to get their annual flu shot, especially if a new coronavirus is spreading. In addition to preventing or mitigating the severity of flu, the vaccine can simplify the evaluation of patients with flu-like symptoms who may have a more serious condition.  

SARS-CoV-2 is believed to have jumped from animals to humans in an open-air fish and animal market in the city of Wuhan, China before it began to spread from person-to-person in China and other parts of the world. Symptoms can appear anytime between two and 14 days after exposure.

Experts do not yet have a full clinical picture of COVID-19. Still, they do know that some populations are at higher risk for complications and death, including adults over 65 years old, people who live in nursing homes, and people of all ages with chronic conditions (such as diabetes, heart disease, obesity, and lung disease). However, younger people and children have also developed severe illness and complications from COVID-19, so people of all ages should take steps to prevent the disease.

Yale Medicine Infectious Diseases has an entire team dedicated to caring for patients with infections, including coronaviruses. This team closely monitors both existing and emerging infectious diseases, and is at the forefront of the latest testing, diagnostic, and treatment approaches. Yale doctors have also performed important research to contribute to better treatment and safe, effective vaccines for SARS-CoV-2