What is coronavirus?

Medically reviewed on July 14, 2020. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

COVID-19 (coronavirus disease 2019) is an infectious disease caused by the novel coronavirus SARS-CoV-2—or severe acute respiratory syndrome coronavirus 2. This new (or novel) coronavirus disease was detected in China in late 2019 and has since spread globally.

But what exactly is this virus?

With the research, news, and numbers changing daily, it’s important to take a closer look at the details of coronavirus to better aid your understanding of the new reality brought on by the pandemic.

Here, we’ll cover aspects of the virus—like its origin, types of transmission, mortality rate, symptoms, coronavirus testing, and prevention.

Origin of the novel coronavirus

Many experts believe that the novel coronavirus may have originated in bats. Since the virus transferred to humans in Wuhan, China toward the end of 2019, the virus has spread from person to person around the world.

Coronaviruses are a family of viruses that can infect both humans and animals. The viruses are common in animals like camels and cows, but transmission from animal to humans—which is what occurred with the novel coronavirus—is rare.

Once the novel coronavirus mutated, allowing it to jump from animals to humans, it then spread from person-to-person through respiratory droplets produced by people with the infection (via coughing, sneezing, or talking). The transmission of the infection is similar to how germs spread in the flu or common cold. The infection leads to coronavirus disease 2019, or COVID-19. Many cases of COVID-19 are mild, though some can lead to severe illness and death.

The coronavirus today

As the virus continues to spread, staying up-to-date with the current state of the global pandemic can prove challenging. Learning more about the virus in terms of region, types of transmission, age, and mortality rate can help you better understand the pandemic’s growth and impact.

Types of transmission

To shed more light on how exactly the virus spreads, the World Health Organization (WHO) has described different transmission classifications for transmission. Here is how the WHO summarizes the five classifications of virus transmission.

Community transmission: Evidenced by (1) the inability to relate confirmed cases through chains of transmission for a large number of cases, or (2) by increasing rates of positive test results as determined through sentinel samples (routine systematic testing of respiratory samples from established laboratories).

Local transmission: Indicates locations where the source of infection is within the reporting location.

Imported cases: Indicates locations where all cases have been acquired outside the location of reporting.

Under investigation: Indicates locations where the type of transmission has not been determined for any cases.

Interrupted transmission: Indicates locations where interruption of transmission has been demonstrated.

Mortality rate, case-fatality rate (CFR), and age

As the pandemic progresses, more people around the world are dying from COVID-19. The amount of deaths differs depending on the country. When considering how dangerous the novel coronavirus is, two metrics are useful: mortality rate and case-fatality rate.

In this context, mortality rate refers to the number of deaths due to COVID-19 compared to a given size of an overall population—typically 100,000. According to data compiled by Johns Hopkins University, the mortality rate of COVID-19 is about 46.5 in the United States.

The case-fatality rate is the proportion of people with COVID-19 who die due to the condition—and depends on the age and health of the population under consideration, the availability of tests, and the healthcare systems of each country.

For COVID-19, deaths are highest in the elderly and those who have pre-existing health conditions, like diabetes, heart disease, and asthma. The CDC estimates these case-fatality rates for people in the following age ranges:

  • Age 85+: 10% to 27%
  • Age 65-84: 3% to 11%
  • Age 55-64: 1% to 3%
  • Age 20-54: less than 1%

To track COVID-19 deaths in the United States and across the world over time, see this tracking chart from the New York Times—which is regularly updated to provide up-to-date, reliable measurements of the pandemic’s impact.

The symptoms of coronavirus

Currently the subject of active research, the symptoms of the novel coronavirus are thought to occur from 2 to 14 days after transmission. However, it’s important to note that some people can be asymptomatic and can transmit the infection even when they aren’t experiencing coronavirus symptoms.

Here are the common symptoms (including flu-like symptoms) that have been linked to COVID-19.

Most common

  • Fever: Low-grade fever that increases over time.
  • Coughing: Especially a dry cough that persists and gets more severe.
  • Fatigue: A general feeling of being tired and worn down.

Some people also experience:

  • Runny nose
  • Nasal congestion
  • Sore throat
  • Diarrhea
  • Muscle or body aches
  • Shortness of breath (breathing difficulties are seen in serious cases)
  • Nausea or vomiting
  • Diarrhea
  • New loss of taste or smell
  • Headache

The symptoms of coronavirus can range from mild to severe depending on the person. It’s estimated that most people—about 80%—recover without needing special treatment. About 15% of people become severely ill and require hospitalization, while 5% become critically ill. For the most up-to-date list of symptoms, please view the CDC website here.

COVID-19 testing

Understanding the available options for COVID-19 testing can help keep you and your loved ones safer during these trying times.

Currently, some people get tested for the novel coronavirus if they are experiencing COVID-19 symptoms or they have had exposure to someone who is infected. If you have a fever and respiratory distress, a healthcare provider may test for the virus in the following way: taking a swab, sending it to the lab for analysis, then waiting for results.

Additionally, there are drive-thru coronavirus testing sites available throughout the country. At these sites, individuals drive to the site, talk to medical personnel, and get on-site testing with a sample taken from the respiratory tract via swab.

The FDA has also authorized some at-home coronavirus tests.


Because there is currently no vaccine for the coronavirus disease, the Centers for Disease Control and Prevention (CDC) recommends following these steps to reduce the risk of infection.

  • Wash your hands often with soap and water for at least 20 seconds, or use an alcohol-based hand sanitizer (that has at least 60% alcohol).
  • Cover your mouth and nose with your elbow or tissue when you cough or sneeze, disposing of any used tissues immediately.
  • Avoid touching your eyes, nose, and mouth if your hands aren't clean.
  • Avoid close contact with anyone who is sick.
  • Avoid sharing dishes, glasses, bedding, and other household items if you're sick.
  • Clean and disinfect surfaces you often touch.
  • Stay home from work, school, and public areas if you're sick.
  • If you do go out in public, or are around people you don’t live with, wear a mask to cover your face.

Additionally, coronavirus social distancing helps decrease the spread of this infectious disease among people. This refers to avoiding crowds and mass gatherings, standing six feet away from others, and staying home unless it’s necessary to go out (to get groceries or prescriptions, for example). If you recently returned from a place that’s experiencing a surge in coronavirus infections, it may be best to self-quarantine to make sure you aren’t unknowingly spreading the infection to others.

Experiencing COVID-19 symptoms and looking for relief? Get COVID-19 treatment online via Everlywell's Virtual Care offering.

FIT at 45: Here’s why colon cancer screenings are more important than ever during COVID-19

Everlywell COVID-19 Test Home Collection Kit DTC now available to asymptomatic individuals

How do you get tested for allergies?


1. Coronavirus disease 2019 (COVID-19) Situation Report – 63. World Health Organization. URL. Accessed July 14, 2020.

2. Coronavirus Disease 2019 (COVID-19). Centers for Disease Control and Prevention (CDC). URL. Accessed July 14, 2020.

3. Trends in United States COVID-19 Hospitalizations, Deaths, Emergency Department (ED) Visits, and Test Positivity by Geographic Area. Centers for Disease Control and Prevention (CDC). URL. Accessed July 14, 2020.

4. How COVID-19 Spreads. Centers for Disease Control and Prevention (CDC). URL. Accessed July 14, 2020.

5. Mortality Analyses. Johns Hopkins Coronavirus Resource Center. URL. Accessed July 14, 2020.

6. Severe Outcomes Among Patients with Coronavirus Disease 2019 (COVID-19) — United States, February 12–March 16, 2020. Centers for Disease Control and Prevention (CDC). URL. Accessed July 14, 2020.

7. Symptoms of Coronavirus. Centers for Disease Control and Prevention (CDC). URL. Accessed July 14, 2020.

8. Coronavirus disease 2019 (COVID-19). Mayo Clinic. URL. Accessed July 14, 2020.

9. Coronavirus disease 2019 (COVID-19) Situation Report – 41. World Health Organization. URL. Accessed July 14, 2020.

10. How to Protect Yourself & Others. Centers for Disease Control and Prevention (CDC). URL. Accessed July 14, 2020.

11. Coronavirus, Social and Physical Distancing and Self-Quarantine. Johns Hopkins Medicine. URL. Accessed July 14, 2020.

Everlywell makes lab testing easy and convenient with at-home collection and digital results in days. Learn More