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Coronavirus disease 2019 (COVID-19) is the official name given by the World Health Organization (WHO) to the disease caused by SARS-CoV-2, the new coronavirus that surfaced in Wuhan, China in 2019 and spread around the globe. The WHO has characterized COVID-19 as a pandemic, a disease outbreak that covers a wide geographic area and affects an exceptionally high proportion of people.

Knowledge about the spread and potential treatment of COVID-19 is evolving rapidly as scientists investigate the disease. There is much to learn about how the virus spreads and why it affects people in different ways—some have mild symptoms or no symptoms at all, while others experience severe symptoms and even die from the disease. While doctors are still working to develop a complete clinical picture, people ages 65 and older, and people of all ages with underlying health conditions appear to be at higher risk of developing serious illness

But the disease has also led to serious illness and deaths in younger and middle-aged adults who are otherwise healthy. While COVID-19 is rare in children, doctors are concerned about a condition they are calling pediatric multisystem inflammatory syndrome (PMIS), which can infect infants through teenagers and can cause dangerous inflammation levels throughout the body. While more information is needed, medical experts believe PMIS is related to COVID-19.

“There is still much to learn about how this pathogen is transmitted between individuals,” says Richard Martinello, MD, a Yale Medicine infectious diseases specialist and medical director of infection prevention at Yale New Haven Health. “Data is needed not only to better understand when those who become ill shed the virus, but also which body fluids contain the virus and how those may contaminate surfaces and even the air surrounding them.”

From where did COVID-19 originate?

The coronavirus SARS-CoV-2 was never seen before it surfaced in December 2019—when it was believed to have somehow passed from an animal to a human at a large seafood and live animal market in Wuhan. By early 2020, the virus was spreading from person to person around the globe. SARS-CoV-2 is one of seven known coronaviruses that cause illnesses that range from the common cold to severe acute respiratory syndrome (SARS), an epidemic that killed almost 800 people in 2002 and 2003.

COVID-19 is the first pandemic known to be caused by the emergence of a new coronavirus—novel influenza viruses caused four pandemics in the last century (which is why some of the response to the new disease is being adapted from existing guidance developed in anticipation of an influenza pandemic). 

What are the symptoms of COVID-19?

The CDC believes COVID-19 is most contagious when people who have it are most symptomatic, and symptoms of COVID-19 can appear anytime between two and 14 days after exposure.

The following symptoms have been identified:

  • Fever
  • Cough
  • Shortness of breath and difficulty breathing
  • Chills
  • Repeated shaking with chills
  • Muscle pain
  • Headache
  • Sore throat
  • New loss of taste or smell

This list does not include all possible symptoms. Less common symptoms, including gastrointestinal symptoms like nausea, vomiting, or diarrhea, have also been reported, according to the Centers for Disease Control and Prevention (CDC).

You should call your medical provider for advice if you have been in close contact with a person known to have COVID-19 or if you live in an area with ongoing spread of the disease and notice these symptoms.

Seek medical attention immediately if you experience emergency warning signs, including difficulty breathing or shortness of breath, persistent pain or pressure in the chest, new confusion or ability to arouse, or bluish lips or face. This list is not inclusive, so consult your medical provider if you notice other concerning symptoms. 

Who is at risk for COVID-19 and complications from the disease?

Anyone who may have been exposed to the SARS-CoV-2 is at risk for COVID-19.

While the method of transmission of the new SARS-CoV-2 is not yet clear, other coronaviruses have moved from person to person through handshaking or 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.

Just how transmissible SARS-CoV-2 is remains unclear. A study published in The New England Journal of Medicine showed that the virus may be stable for several hours in aerosols (in this case, droplets from an infected person dispersed in air or gas) and for several hours to days on surfaces. “Until we understand more about the granular details of how SARS-CoV-2 passes from person to person, public health dictates that people maintain social distancing, wash hands, and frequently disinfect high-touch surfaces," says infectious diseases specialist Jaimie Meyer, MD.

How is COVID-19 treated?

There are no treatments that have been proven to be safe and effective, but researchers are investigating a number of existing medications. One such treatment is an antiviral drug called remdesivir, which is has been used to treat suspected or laboratory-confirmed COVID-19 in adults and children hospitalized with severe disease. Experts are still studying the safety and effectiveness of remdesivir and other treatments. 


What precautions can I take to avoid COVID-19?

Researchers are working on a vaccine to prevent the new coronavirus, but it’s hard to predict when one might become available. In the meantime, the CDC recommends the following preventive actions:

  • Wash hands with soap and water for at least 20 seconds. If soap isn’t available, use a hand sanitizer with at least 60% alcohol.
  • Stay home if you’re sick
  • Avoid touching nose, eyes, and mouth. Use a tissue to cover a cough or sneeze, then dispose of it in the trash
  • Use a household wipe or spray to disinfect doorknobs, light switches, desks, keyboards, sinks, and other objects and surfaces that are frequently touched
  • Health care providers who may be in the position of caring for a patient with the virus should follow infection control protocols. 
  • Practice social distancing by staying at least 6 feet (about 2 arms’ lengths) from other people
  • Avoid gathering in large groups, crowded places, or mass gatherings
  • Wear a cloth face mask in public settings where other social distancing measures are difficult to maintain, especially in areas where there is significant community transmission.


Will a flu shot protect against developing a severe case of COVID-19?

While a flu shot won’t prevent or reduce severity of COVID-19, public health authorities strongly advise everyone to get their annual flu shot. In addition to preventing or mitigating the severity of flu, the vaccine may simplify the evaluation of patients during the flu season who may have a more serious condition.  

How is Yale Medicine prepared to handle patients with COVID-19?

Yale Medicine Infectious Diseases has an entire team with experience treating both existing and emerging diseases. This team is at the forefront of the latest testing, diagnostic, and treatment approaches.

 Yale New Haven Health is offering a call center for patients and people in the community who have questions about COVID-19. Health care professionals are available to answer specific questions Monday through Friday, 7 a.m. to 7 p.m. Call 203-688-1700 (toll-free, 833-484-1200.)