COVID-19 is a highly contagious infectious disease caused by the virus SARS-CoV-2. SARS-CoV-2 belongs to the family of viruses known as coronaviruses.

In most people who develop it, COVID-19 causes a mild respiratory illness similar to influenza. In some individuals, however, it can lead to a severe respiratory condition that requires hospitalization.

People can be without symptoms, or asymptomatic, despite having a SARS-CoV-2 infection. This means that they can still spread the virus to others even though they do not feel unwell. This makes COVID-19 potentially dangerous, as it is highly infectious and can cause severe illness.

At this time, there is no cure for COVID-19. However, people can protect themselves and help prevent the spread of this novel coronavirus by:

  • washing their hands frequently
  • not touching their face
  • avoiding close contact with people who are sick
  • avoiding crowds and maintaining 6 feet of distance from others
  • wearing a mask or face covering in public places

Keep reading to learn more about COVID-19, including the symptoms, likely incubation period, special considerations for high risk groups, and more.

a medical professional at a Drive Through COVID-19 Testing Facility Share on Pinterest
A person can still transmit SARS-CoV-2 even if they do not have symptoms.
Image credit: Joe Raedle/Getty Images

Coronaviruses are a large family of viruses that cause respiratory illnesses. Those range from the common cold to more severe diseases, such as Middle East respiratory syndrome (MERS) and severe acute respiratory syndrome (SARS).

The symptoms of COVID-19 are usually mild and tend to begin 2–14 days after exposure to the virus. Symptoms may vary from person to person.

The Centers for Disease Control and Prevention (CDC) report that COVID-19 may cause the following symptoms:

  • fever, chills or both
  • a cough
  • shortness of breath or difficulty breathing
  • tiredness or fatigue
  • headache
  • muscle aches
  • a new loss of taste or sense of smell
  • sore throat
  • congestion or a runny nose
  • nausea or vomiting
  • diarrhea

The World Health Organization (WHO) state that less common symptoms include a skin rash, conjunctivitis (inflammation of the eyes), and discoloration of the fingers or toes.

According to the WHO, about 80% of people recover from COVID-19 without needing treatment in a hospital. However, they note that approximately 1 in every 5 people who get COVID-19 become seriously ill and may develop difficulty breathing. About 5% need intensive care.

According to the CDC, older adults and people of any age with underlying medical concerns, such as chronic lung disease, heart problems, or type 2 diabetes, are at higher risk of severe illness from COVID-19.

Other groups might be at an increased risk too, such as those with asthma, high blood pressure (hypertension), liver disease, and type 1 diabetes. However, the research is limited.

The following sections will discuss these groups and their risk of severe illness in more detail.

Older adults

The CDC say that the risk of severe illness from COVID-19 increases as a person gets older. People in their 50s are at a higher risk than those in their 40s. The greatest risk is among people 85 and above.

The CDC say that around 8 out of 10 deaths reported in the United States have been in people aged 65 and older.

Individuals in this age group should discuss their risks with a doctor and let them know if they are experiencing any symptoms of COVID-19.

People with preexisting health conditions

Currently, there is little information about how COVID-19 affects people with certain preexisting health conditions. However, researchers have identified the following conditions that could increase a person’s risk of serious illness due to COVID-19:

Chronic respiratory conditions

These include:

Since COVID-19 is a respiratory disease, those with preexisting respiratory conditions may have a higher risk of developing a serious illness.

For example, because asthma can worsen due to other respiratory infections, such as colds, those with asthma should be especially careful to follow all protection and prevention precautions for COVID-19.

It is always important that individuals with asthma keep their symptoms under control by taking their prescribed asthma medications.

Hypertension and cardiovascular conditions

People with the following serious heart conditions have an increased risk of severe illness from COVID-19:

  • coronary artery disease
  • heart failure
  • pulmonary hypertension
  • weakened heart muscle, known as cardiomyopathy

People with these conditions should continue to follow their healthcare provider’s advice about prescription medication (including ACE inhibitors), diet, and exercise while following physical distancing precautions.


The CDC state that people with type 2 diabetes are at an increased risk of severe illness from COVID-19, and that this might also apply to people with type 1 diabetes, though more research is needed.


Having cancer increases a person’s risk of severe illness from COVID-19. Researchers do not know if having a history of cancer also increases a person’s risk.

People undergoing cancer treatment, such as chemotherapy, may also be at greater risk of serious illness due to COVID-19. This is because their immune systems may be weaker as a result of their cancer treatment.

Sickle cell disease

Individuals with sickle cell may be at risk of having more severe symptoms due to COVID-19.

It is also important that people with sickle cell avoid any possible triggers.

Immunocompromised after organ transplant

Organ transplants cause a person to be immunocompromised or have a weakened immune system due to taking medications that suppress the immune system. This can increase the risk of serious illness due to COVID-19.

An individual in this situation should continue taking any prescribed medicines or treatments. The CDC recommend having at least a 30-day supply of medication on hand.


According to the CDC, people with severe obesity, or a body mass index (BMI) of 40 or above, have an increased risk of severe illness. They say that people with overweight, who have a BMI of 25 to 30, might also have an increased risk.

There has not been much research into how COVID-19 affects pregnant people and babies.

The sections below will discuss what researchers do know.


Changes in the immune system during pregnancy may increase the risk of severe illness from respiratory viruses such as the flu.

According to the CDC, those who are pregnant also may be at an increased risk of severe illness from COVID-19. People who have COVID-19 during pregnancy may have a higher risk of some problems, such as preterm birth.

During pregnancy, people should continue to attend their healthcare appointments, take precautions to protect themselves against COVID-19, and report any possible symptoms to their healthcare provider.

Learn more about pregnancy and COVID-19 here.


The risk of a mother transmitting COVID-19 to a newborn is low, especially when the mother takes precautions when caring for the newborn, such as hand hygiene and wearing a mask.

People with COVID-19 should talk to their healthcare team about the risks and benefits of sharing a room with their newborn so they can make an informed decision.

The WHO state that the COVID-19 incubation period, or the time between catching the virus and starting to show symptoms, is often around 5–6 days, but it can range from 1–14 days.

The SARS-CoV-2 virus appears to spread primarily through close person-to-person contact.

When someone who has the infection talks, coughs, or sneezes, tiny droplets containing the virus spray into the air from their nose or mouth. Anyone within 6 feet (2 meters) of someone who has the virus is close enough to potentially contract it.

A study in The New England Journal of Medicine showed that the virus can survive in aerosols for up to 3 hours.

However, it is important to note that the tests in this study used aerosol machines under laboratory settings rather than human breath. The aerosol from a person’s cough may not stay in the air for as long.

The study also found that the virus survives for longer on surfaces. It can last for up to 24 hours on cardboard and for as long as 72 hours on plastic and stainless steel surfaces.

The coronavirus can spread when a person touches their eyes, nose, or mouth after touching a surface or object that it has contaminated, although this is not currently thought to be a major source of transmission.

It is also possible for people who have no symptoms of infection to pass the virus on to others.

Learn more about how the novel coronavirus spreads here.

People can protect themselves from contracting the virus and prevent its spread by following these precautions:

  • Washing hands: Washing the hands often with soap and water for at least 20 seconds is the most important practice. When soap and water are not available, use hand sanitizer. Some key times to wash the hands include before eating and preparing food, after using the bathroom, after being in public, and when the hands are visibly dirty.
  • Avoiding touching the eyes, nose, and mouth: This prevents the virus from entering the body.
  • Keeping a distance: People should keep a distance of 6 feet (2 meters) between themselves and others.
  • Practicing good public hygiene: Cover all coughs and sneezes with a tissue or elbow, not the hands, and dispose of the tissue immediately.
  • Cleaning surfaces often: Clean and disinfect frequently touched objects and surfaces, such as tabletops, counters, and doorknobs.
  • Avoiding sharing: Avoid sharing personal household items, such as cups and towels.
  • Getting vaccinated: Get a flu vaccine, if possible.
  • Using a cloth face covering: In the U.S., the CDC recommend that everyone wear a cloth face covering in public places where it is difficult to stay 6 feet away from others. This will help slow the spread of the virus by people who do not know that they have it. People should continue to wash their hands often and practice physical distancing. Learn how to make a mask at home here.

If a person believes that they have had exposure to the virus and develops symptoms, they should contact a healthcare provider to determine whether they need a medical evaluation or additional care.

If the symptoms are not severe, the person should begin self-isolation. No other action is necessary at this time. Most people have mild symptoms and are able to recover at home.

To avoid spreading COVID-19 to others, people showing symptoms should take the following steps:

  • staying home unless a doctor advises them to seek medical care, or if there is an emergency
  • isolating themselves in a separate room, away from others in the household
  • wearing a face mask or scarf to prevent any saliva or respiratory droplets from spreading to others
  • calling ahead before visiting a doctor’s office or urgent care center
  • avoiding public transport, cabs, and ride sharing unless absolutely necessary

At this time, there is no cure for COVID-19. Treatment is supportive and aimed at providing relief from the symptoms.

Supportive treatment measures are similar to those for a cold or flu. They may include:

  • getting plenty of rest
  • drinking plenty of fluids and eating small but frequent nutritious meals
  • taking acetaminophen for pain and fever

Anyone with COVID-19 should contact a doctor or other healthcare provider if their symptoms worsen.

Read more about possible treatments for COVID-19 here.

If a person is showing any of the following emergency warning signs for COVID-19, the CDC say that they should seek emergency medical care:

  • difficulty breathing
  • persistent pain or pressure in the chest
  • new confusion
  • an inability to stay awake
  • bluish lips or face

At this time, the situation regarding COVID-19 is constantly evolving. Statistics on confirmed cases, survival and death rates, and overall outlook seem to vary greatly and can depend on where a person lives, among other factors.

For up-to-date news and statistics, see our live COVID-19 updates page.

COVID-19 is a highly contagious respiratory disease caused by the virus SARS-CoV-2.

The majority of people with COVID-19 will experience a mild illness, similar to the flu, or may be asymptomatic. However, older adults and people with certain conditions may be more at risk of developing a more serious illness.

There is currently no cure for COVID-19. Treatment aims to relieve the impact of the symptoms.

Prevention strategies, such as physical distancing, frequent hand washing, avoiding touching the face, and wearing a face covering in public will help protect individuals from this novel coronavirus.