visual image of the covid 19 virus

What is COVID-19?

COVID-19 is a type of coronavirus, which is a large group of infections that cause upper respiratory tract infections. The virus can cause coughing, fever, shortness of breath and other symptoms. It is very contagious and can spread from one person to another rapidly.

Most people have mild or moderate symptoms. However, people with existing health conditions may be at a higher risk of serious complications. More than a million people have died of COVID-19 in the United States, while tens of thousands are hospitalized each year.

What are the symptoms of COVID-19?

Symptoms of COVID-19 can vary from one person to another. You may have no symptoms or very mild ones, or symptoms could be severe. COVID-19 symptoms are similar to those of other respiratory illnesses, such as the cold or flu, and may include:

  • Fever
  • Fatigue
  • Cough
  • Chills
  • Congestion
  • Headache
  • Sore throat
  • Muscle aches and pain
  • Runny nose
  • Shortness of breath
  • Loss of smell or taste
  • Nausea and/or vomiting
  • Diarrhea
A patient checking her temperature to keep an eye on covid symptoms

How long does COVID-19 last?

Most people feel better within a few weeks, but some people experience symptoms that last much longer. According to the CDC, Long COVID is a condition that occurs after a COVID-19 infection and lasts for at least three months.

What causes COVID-19?

COVID-19 is caused by a type of coronavirus called SARS-CoV-2, which is short for severe acute respiratory syndrome coronavirus 2.

How does COVID-19 spread?

COVID-19 spreads through droplets or small particles released into the air when an infected person breathes, coughs, sneezes or talks. You can get COVID-19 if you breathe in these droplets and particles when you are close to an infected person.

Less frequently, COVID-19 can spread through droplets on surfaces you touch, such as a door handle or elevator button. The virus can then get into your body if you touch your eyes, nose or mouth.

What is the incubation period for COVID-19?

It typically takes between two and 14 days for symptoms to develop after exposure to the virus that causes COVID-19. On average, symptoms start five to six days after exposure.

How long is COVID-19 contagious?

COVID-19 can be contagious from one to two days before and up to eight to 10 days after symptoms begin. You may still be contagious even if you do not have symptoms or have previously had COVID-19. You can also pass it on if you have had the vaccine.

When did COVID-19 start?

The COVID-19 timeline began in late 2019, when the SARS-CoV-2 virus emerged in China. It caused pneumonia-type symptoms that did not respond to existing treatments. The virus then rapidly spread around the world.

The first cases were diagnosed in the United States in January 2020. In March 2020, the World Health Organization officially declared COVID-19 a global pandemic.

Is COVID-19 still around?

While COVID-19 is no longer considered a global health emergency, it continues to make people seriously ill in the United States and worldwide. Millions of Americans get sick with COVID-19 each year, with many requiring hospitalization.

COVID-19 risk factors

​​​​​​​​​​​​​

COVID-19 can affect anyone at any age. It is a very contagious illness that spreads easily from person to person. However, certain factors can increase your risk for severe illness or developing serious complications.

Fortunately, for many people with these risk factors, receiving the COVID-19 vaccine helps prevent infection and may lower the risk of complications if someone gets sick.

Age

Age is a leading risk factor. More than four in five COVID-19 deaths occur in people over age 65.

Chronic health conditions

Chronic health conditions can contribute to severe COVID-19 infection in different ways. Often, though, these conditions or their treatments weaken your immune system, making it harder for your body to fight the infection.

Many chronic conditions can increase your risk of severe illness or complications, and the more chronic health conditions you have, the higher your risk. They include:

  • Cancer
  • Chronic kidney disease
  • Chronic lung conditions, such as asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis, tuberculosis and interstitial lung disease
  • Dementia
  • Diabetes
  • Heart disease
  • Human immunodeficiency virus (HIV)
  • Liver disease
  • Sickle cell disease and other blood disorders
  • Vascular conditions, such as stroke

    Lifestyle factors

    Your lifestyle can make you more susceptible to COVID-19, as well. For example, living with obesity triples your chance of being hospitalized with COVID-19. Physical inactivity can contribute to excess weight. Smoking damages your lungs.

    Pregnancy

    Pregnant people do not seem to get COVID-19 at higher rates than non-pregnant people, but pregnancy can increase your risk of severe infection, COVID-19-related health concerns, preterm birth and preeclampsia.

    Having chronic health conditions further increases your risk, and the increased risk continues for about a month after you have your baby.

    How does COVID-19 affect the body?

    COVID-19 typically causes mild to moderate flu-like symptoms, which usually go away within a few weeks. It can also affect other parts of your body and cause long-term complications. In severe cases, COVID-19 can be fatal. Getting an up-to-date COVID-19 vaccination may reduce your risk of serious illness.

    Complications may include:

    • Brain and nervous system problems: Some people experience “brain fog” (difficulty concentrating or thinking) or numbness or tingling in their arms and legs.
    • Damage to your heart and blood vessels: COVID-19 can increase your chance of heart problems, such as inflammation and an irregular heartbeat.
    • Eye problems: A few people who have COVID-19 develop eye problems, which may be linked to inflammation.
    • Gastrointestinal symptoms: The virus may remain in your gastrointestinal tract for weeks or months, causing diarrhea, nausea and vomiting.
    • Kidney problems: Kidney issues have been linked to COVID-19 infections.
    • Respiratory failure: This is the most common cause of death among people with COVID-19.
    • Skin conditions: Rarely, people can develop rashes when they have COVID-19 or in the weeks or months afterward.

    Diagnosing COVID-19

    COVID-19 is diagnosed through tests that can detect the virus using a nasal swab or a sample of saliva taken from your mouth. You can buy home tests from your pharmacy, or you can get tested at a medical center, hospital or pharmacy.

    These tests are the most reliable way to determine if you are sick. COVID-19 symptoms are similar to those of many other respiratory viruses, so it’s hard to know if you have it based on symptoms alone.

    • Viral tests

      Viral tests that can tell if you have a current COVID-19 infection. Home tests can give you a result within minutes. However, they are not as accurate as tests that are sent to a lab.

      There are two basic types:

      • Antigen tests: You can perform these tests at home. You test a swab from your nose or mouth to see if you are currently infected. It is common to get a false negative, so experts recommend repeating the test if it is negative.
      • Nucleic acid amplification tests: These tests are more accurate than home tests. The most common type is known as a polymerase chain reaction, or PCR, test. A sample is sent to a laboratory for testing to see if you have the virus.
    • Antibody tests

      Antibody tests are generally not used to diagnose COVID-19, but they can tell your doctor whether you have been infected in the past or if your body responded to a COVID-19 vaccine. These tests are not used often. Your doctor may suggest one if, for example, you’re showing signs of complications that may have been caused by COVID-19.

      Your body produces antibodies, which are special proteins that help your body fight infections, whenever you are sick. An antibody test uses a sample of blood to see if your body has produced antibodies to the SARS-CoV-2 virus.

    How to treat COVID-19

    ​​​​​​​​​​​​​

    Many mild to moderate cases of COVID-19 may be safely managed at home. Your symptoms will usually go away on their own with rest, plenty of fluids and over-the-counter medicines if needed. COVID-19 that becomes severe or develops in people with certain risk factors may require prescription medications. In very serious cases, the illness requires oxygen therapy or being placed on a ventilator.

    Medication

    Doctors typically only prescribe COVID-19 medications to people at risk of getting seriously ill or developing complications of the virus. Antiviral medications used to treat COVID-19 include:

    • Molnupiravir: This is an oral medicine (taken by mouth) that is most effective when taken within five days of symptoms starting.
    • Paxlovid: This is the most prescribed antiviral medicine for COVID-19. It can slow the virus and prevent more severe illness. You should start taking it within five days of developing symptoms.
    • Veklury (remdesivir): This is a medication delivered through intravenous (IV) infusion. For people who are not hospitalized for their illness, doctors usually recommend starting it within seven days of when symptoms appear.

    Other treatment

    If you are severely ill, your doctor may admit you to the hospital or an outpatient center so you can receive oxygen therapy or supplemental oxygen. You are given oxygen through a tank or a device called a concentrator, which extracts oxygen from the air.

    Is there a cure for COVID-19?

    There is no cure for COVID-19. Antiviral medicines may slow the virus and prevent severe illness or death, but there is always a chance they may not fully treat the infection.

    Currently, receiving the COVID-19 vaccine offers the most effective protection against illness. The Centers for Disease Control and Prevention recommends it for anyone age 65 and older and people at high risk of serious infection. Other groups, such as people who never received the vaccine, also benefit.

    Locations for COVID-19 care

    You can receive care and advice for preventing COVID-19 at our primary care clinics, urgent care clinics and specialty centers throughout North and Central Texas. Your provider can also help you decide if the COVID-19 vaccination is right for you.

    Read More

    Frequently asked questions

    • Can you have COVID-19 without a fever?

      Yes, you can have COVID-19 without a fever. Fever is a common symptom, but not everyone has one. If you have been exposed to someone with COVID-19 or have other respiratory symptoms, take a test or contact your doctor.

    • How long does it take to recover from COVID-19 at home?

      Most people recover from COVID-19 at home within a few weeks. However, it may take longer for some people.

    • What should I do if I test positive for COVID-19?

      If you test positive for COVID-19, the next steps depend on whether you have risk factors for severe infection or complications.

      If you are generally healthy and have no risk factors, home care with rest, fluids and over-the-counter medications may help you feel better.

      If you are over 65 or have other risk factors, call your doctor. They can prescribe medications that are usually most effective if started within a few days of your symptoms appearing.

    • When should I test again after testing positive for COVID-19?

      If you have symptoms and have already tested positive for COVID-19 in the last 90 days, you can take an antigen test. If you do not have symptoms and your first positive test result was within the last 30 days, then you do not need to test again.

      This is because you may continue to have a positive result after a previous infection. Ask your doctor if you are unsure whether you should take a test.

    • Should I go to the doctor if I have COVID-19?

      You should go to the doctor if you have COVID-19 and are at risk of severe infection or complications. But, in most cases, you can treat COVID-19 at home.

      Call 911 or get medical help right away if you have severe symptoms, such as chest pain or difficulty breathing.

    • How long do you have to quarantine with COVID-19?

      The Centers for Disease Control and Prevention (CDC) advises staying home and away from others for 24 hours after you feel better and are fever-free (without medication).

      The latest COVID-19 guidelines recommend taking additional precautions for five days afterward, such as wearing a mask.

    • What are the worst days of COVID-19?

      Some people feel worse around seven to 10 days after their symptoms begin, but symptoms vary from one person to another. You may find that yours are mild and resolve quickly.

      Always call your doctor if you have severe symptoms or are at high risk of complications.

    How we reviewed this page

    Current version
    • November 10, 2025

    • Medically reviewed by:

      Stephanie Kreiling, MPH, BSN, RN, CIC