Overview
Coronavirus
Coronavirus
Coronavirus is a family of viruses that can cause respiratory illnesses such as the common cold, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).
Coronaviruses are a family of viruses that can cause illnesses such as the common cold, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). In 2019, a new coronavirus was identified as the cause of a disease outbreak that originated in China.
The virus is known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The disease it causes is called coronavirus disease 2019 (COVID-19). In March 2020, the World Health Organization (WHO) declared the COVID-19 outbreak a pandemic.
Public health groups, including the U.S. Centers for Disease Control and Prevention (CDC) and WHO, are monitoring the COVID-19 pandemic and posting updates on their websites. These groups have also issued recommendations for preventing and treating the virus that causes COVID-19.
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Symptoms
Signs and symptoms of coronavirus disease 2019 (COVID-19) may appear 2 to 14 days after exposure. This time after exposure and before having symptoms is called the incubation period. You can still spread COVID-19 before you have symptoms (presymptomatic transmission). Common signs and symptoms can include:
- Fever
- Cough
- Tiredness
Early symptoms of COVID-19 may include a loss of taste or smell.
Other symptoms can include:
- Shortness of breath or difficulty breathing
- Muscle aches
- Chills
- Sore throat
- Runny nose
- Headache
- Chest pain
- Pink eye (conjunctivitis)
- Nausea
- Vomiting
- Diarrhea
- Rash
This list isn't complete. Children have similar symptoms to adults and generally have mild illness.
The severity of COVID-19 symptoms can range from very mild to severe. Some people may have only a few symptoms. Some people may have no symptoms at all, but can still spread it (asymptomatic transmission). Some people may experience worsened symptoms, such as worsened shortness of breath and pneumonia, about a week after symptoms start.
Some people experience COVID-19 symptoms for more than four weeks after they're diagnosed. These health issues are sometimes called post-COVID-19 conditions. Some children experience multisystem inflammatory syndrome, a syndrome that can affect some organs and tissues, several weeks after having COVID-19. Rarely, some adults experience the syndrome too.
People who are older have a higher risk of serious illness from COVID-19, and the risk increases with age. People who have existing medical conditions also may have a higher risk of serious illness. Certain medical conditions that may increase the risk of serious illness from COVID-19 include:
- Serious heart diseases, such as heart failure, coronary artery disease or cardiomyopathy
- Cancer
- Chronic obstructive pulmonary disease (COPD)
- Type 1 or type 2 diabetes
- Overweight, obesity or severe obesity
- High blood pressure
- Smoking
- Chronic kidney disease
- Sickle cell disease or thalassemia
- Weakened immune system from solid organ transplants or bone marrow transplants
- Pregnancy
- Asthma
- Chronic lung diseases such as cystic fibrosis or pulmonary hypertension
- Liver disease
- Dementia
- Down syndrome
- Weakened immune system from bone marrow transplant, HIV or some medications
- Brain and nervous system conditions, such as strokes
- Substance use disorders
This list is not complete. Other medical conditions may increase your risk of serious illness from COVID-19.
When to see a doctor
If you have COVID-19 signs or symptoms or you've been in contact with someone diagnosed with COVID-19, contact your health care provider right away for medical advice. Your health care provider will likely recommend that you get tested for COVID-19. If you have emergency COVID-19 symptoms, such as trouble breathing, seek care immediately. If you need to go to a hospital, call ahead so that health care providers can take steps to ensure that others aren't exposed.
If you have emergency COVID-19 signs and symptoms, seek care immediately. Emergency signs and symptoms can include:
- Trouble breathing
- Persistent chest pain or pressure
- Inability to stay awake
- New confusion
- Pale, gray or blue-colored skin, lips or nail beds — depending on skin tone
This list isn't complete. Let your health care provider know if you are an older adult or have chronic medical conditions, such as heart disease or lung disease, as you may have a greater risk of becoming seriously ill with COVID-19.
More Information
- COVID-19 vs. flu: Similarities and differences
- COVID-19, cold, allergies and the flu
- Unusual symptoms of coronavirus
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Causes
Infection with severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2, causes coronavirus disease 2019 (COVID-19).
The virus that causes COVID-19 spreads easily among people. Data has shown that the COVID-19 virus spreads mainly from person to person among those in close contact. The virus spreads by respiratory droplets released when someone with the virus coughs, sneezes, breathes, sings or talks. These droplets can be inhaled or land in the mouth, nose or eyes of a person nearby.
Sometimes the COVID-19 virus can spread when a person is exposed to very small droplets or aerosols that stay in the air for several minutes or hours — called airborne transmission.
The virus can also spread if you touch a surface with the virus on it and then touch your mouth, nose or eyes. But the risk is low.
The COVID-19 virus can spread from someone who is infected but has no symptoms. This is called asymptomatic transmission. The COVID-19 virus can also spread from someone who is infected but hasn't developed symptoms yet. This is called presymptomatic transmission.
It's possible to get COVID-19 more than once.
When a virus has one or more new mutations it’s called a variant of the original virus. The omicron (B.1.1.529) variant spreads more easily than the original virus that causes COVID-19 and the delta variant. However, omicron appears to cause less severe disease. People who are fully vaccinated can get breakthrough infections and spread the virus to others. But the COVID-19 vaccines are effective at preventing severe illness. This variant also reduces the effectiveness of some monoclonal antibody treatments. Omicron has a few major offshoots (sublineages), including BA.5 and BA.2.12.1. BA.5 made up about 88% of COVID-19 infections that had genetic sequencing in the U.S. in August, 2022, according to the CDC.
In April, the CDC downgraded the delta variant from a variant of concern to a variant being monitored. This means that the delta variant isn’t currently considered a major public health threat in the U.S.
Risk factors
Risk factors for COVID-19 appear to include:
- Close contact with someone who has COVID-19, especially someone with symptoms
- Being coughed or sneezed on by an infected person
- Being near an infected person when in an indoor space with poor air flow
Complications
Although most people with COVID-19 have mild to moderate symptoms, the disease can cause severe medical complications and lead to death in some people. Older adults or people with existing medical conditions are at greater risk of becoming seriously ill with COVID-19.
Complications can include:
- Pneumonia and trouble breathing
- Organ failure in several organs
- Heart problems
- A severe lung condition that causes a low amount of oxygen to go through your bloodstream to your organs (acute respiratory distress syndrome)
- Blood clots
- Acute kidney injury
- Additional viral and bacterial infections
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- Long-term effects of COVID-19
Prevention
The U.S. Food and Drug Administration (FDA) has given emergency use authorization to some COVID-19 vaccines in the United States. The FDA has approved the Pfizer-BioNTech COVID-19 vaccine, now called Comirnaty, to prevent COVID-19 in people age 12 and older. The FDA has given emergency use authorization to Pfizer-BioNTech COVID-19 vaccines for ages 6 months through 11 years.
The FDA has approved the Moderna vaccine, now called Spikevax, to prevent COVID-19 in people age 18 and older. The FDA has also authorized the Moderna COVID-19 vaccine in children ages 6 months through 17 years old. The FDA has also authorized the Novavax COVID-19, adjuvanted vaccine to prevent COVID-19 in people age 12 and older.
Due to the risk of a potentially life-threatening blood-clotting problem, the FDA is restricting use of the Janssen/Johnson & Johnson vaccine to certain people age 18 and older. Examples include people who had a severe allergic reaction after getting an mRNA COVID-19 vaccine and people who can't get an mRNA COVID-19 vaccine due to limited access or personal or religious concerns. If you get this vaccine, be sure to understand the risks and symptoms of the blood-clotting problem.
A vaccine can prevent you from getting the COVID-19 virus or prevent you from becoming seriously ill if you get the COVID-19 virus. In addition, COVID-19 vaccination might offer better protection than getting sick with COVID-19. A recent study showed that unvaccinated people who already had COVID-19 are more than twice as likely as fully vaccinated people to get reinfected with COVID-19.
After getting vaccinated, you can more safely return to many activities you may not have been able to do because of the pandemic. However, if you are in an area with a high number of people with COVID-19 in the hospital and new COVID-19 cases, the CDC recommends wearing a mask indoors in public. You're considered fully vaccinated two weeks after you get a second dose of an mRNA COVID-19 vaccine, after two doses of the Novavax vaccine, or two weeks after you get a single dose of the Janssen/Johnson & Johnson COVID-19 vaccine. You are considered up to date with your vaccines if you have gotten all recommended COVID-19 vaccines, including booster doses, when you become eligible.
An additional primary dose of a COVID-19 vaccine is recommended for people who are vaccinated and might not have had a strong enough immune response.
In contrast, a booster dose is recommended for people who are vaccinated and whose immune response weakened over time. Research suggests that getting a booster dose can decrease your risk of infection and severe illness with COVID-19.
People who have a moderately or severely weakened immune system should get an additional primary shot and a booster shot.
The CDC recommends additional doses and booster doses of COVID-19 vaccines in specific instances:
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Additional primary shot. The CDC recommends an additional primary shot of an mRNA COVID-19 vaccine for some people with weakened immune systems, such as those who have had an organ transplant. People with weakened immune systems might not develop enough immunity after vaccination with two doses of an mRNA COVID-19 vaccine or one dose of the Janssen/Johnson & Johnson COVID-19 vaccine. An additional shot using an mRNA COVID-19 vaccine might improve their protection against COVID-19. This recommendation for an additional mRNA COVID-19 shot is for people ages 6 months and older.
The additional primary shot should be given at least four weeks after a second dose of an mRNA COVID-19 vaccine or one dose of the Janssen/Johnson & Johnson COVID-19 vaccine. The additional primary shot should be the same brand as the other two mRNA COVID-19 vaccine doses that were given. If the brand given isn't known, either brand of mRNA COVID-19 vaccine can be given as a third dose.
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Booster dose. These recommendations differ by age, what vaccines you have been given and the state of your immune system. But in general, people can get the booster shot at least two months after their last shot. People who recently had a positive COVID-19 test may think about waiting three months after their symptoms started to get the booster.
Kids ages 6 months through 5 years who got the Moderna COVID-19 vaccine can get an updated, called bivalent, Moderna COVID-19 vaccine booster. The booster is based on the original virus strain and two omicron strains.
Kids age 5 who got the Pfizer-BioNTech COVID-19 vaccine can only get the updated Pfizer-BioNTech COVID-19 bivalent vaccine booster.
People age 6 and older can choose between the updated Pfizer-BioNTech and the updated Moderna COVID-19 bivalent vaccine boosters.
If you are age 18 or older, and got the Janssen COVID-19 vaccine, you can get either of the mRNA vaccine bivalent boosters at least two months after your shot. People 18 and older may also get a Novavax booster based on the original virus strain as a first booster at least six months after their last shot.
Pregnant people can also get a COVID-19 booster dose.
People age 5 and older who have a weakened immune system and have had all recommended doses of the Moderna, Pfizer-BioNTech or Novavax COVID-19 vaccines can get a booster dose of the updated Pfizer-BioNTech or Moderna COVID-19 bivalent vaccines.
The FDA has also authorized the monoclonal antibodies tixagevimab and cilgavimab (Evusheld) to prevent COVID-19 in some people with weakened immune systems or a history of severe reactions to a COVID-19 vaccine. But Evusheld may provide less or no protection against certain omicron strains of the virus.
There are many steps you can take to reduce your risk of infection from the COVID-19 virus and reduce the risk of spreading it to others. WHO and CDC recommend following these precautions:
- Get vaccinated. COVID-19 vaccines reduce the risk of getting and spreading COVID-19.
- Avoid close contact with anyone who is sick or has symptoms.
- Keep distance between yourself and others when you're in indoor public spaces. This is especially important if you have a higher risk of serious illness. Keep in mind some people may have COVID-19 and spread it to others, even if they don't have symptoms or don't know they have COVID-19.
- Avoid crowds and indoor places that have poor air flow (ventilation).
- Wash your hands often with soap and water for at least 20 seconds, or use an alcohol-based hand sanitizer that contains at least 60% alcohol.
- Wear a face mask in indoor public spaces if you're in an area with a high number of people with COVID-19 in the hospital and new COVID-19 cases, whether or not you're vaccinated. The CDC recommends wearing the most protective mask possible that you'll wear regularly, fits well and is comfortable.
- Improve the air flow indoors. Open windows. Turn on fans to direct air out of windows. If you can't open windows, consider using air filters. And turn on exhaust fans in your bathroom and kitchen. You might also consider a portable air cleaner.
- Cover your mouth and nose with your elbow or a tissue when you cough or sneeze. Throw away the used tissue. Wash your hands right away.
- Avoid touching your eyes, nose and mouth.
- Avoid sharing dishes, glasses, towels, bedding and other household items if you're sick.
- Clean and disinfect high-touch surfaces, such as doorknobs, light switches, electronics and counters, regularly.
- Stay home from work, school and public areas and stay home in isolation if you're sick, unless you're going to get medical care. Avoid public transportation, taxis and ride-hailing services if you're sick.
If you have a chronic medical condition and may have a higher risk of serious illness, check with your doctor about other ways to protect yourself.
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Travel
If you're planning to travel, first check the CDC and WHO websites for updates and advice. The CDC recommends that you wear a mask on planes, buses, trains and other indoor public transportation traveling to, within or out of the U.S., as well as in places such as airports and train stations. Use appropriate hand hygiene when in public. You may also want to talk with your health care provider if you have health conditions that make you more susceptible to respiratory infections and complications.
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By Mayo Clinic Staff
Jan. 20, 2023
FAQs
What causes coronavirus? ›
Coronavirus disease (COVID-19) is an infectious disease caused by the SARS-CoV-2 virus. Most people infected with the virus will experience mild to moderate respiratory illness and recover without requiring special treatment.
What are the 3 main symptoms of Covid? ›a new, continuous cough – this means coughing a lot for more than an hour, or 3 or more coughing episodes in 24 hours. a loss or change to your sense of smell or taste. shortness of breath. feeling tired or exhausted.
What is the number one symptom of coronavirus? ›A fever is the most common symptom of COVID-19, but it's sometimes below 100 F. In a child, a fever is a temperature above 100 F on an oral thermometer or 100.4 F on a rectal one.
What animals can get COVID? ›The virus that causes COVID-19 can spread from people to animals during close contact. Pets worldwide, including cats and dogs, have been infected with the virus that causes COVID-19, mostly after close contact with people with COVID-19. The risk of pets spreading COVID-19 to people is low.
What is COVID cough like? ›A common symptom of COVID-19 is a dry cough, which is also known as an unproductive cough (a cough that doesn't produce any phlegm or mucus). Most people with dry cough experience it as a tickle in their throat or as irritation in their lungs.
How long does COVID-19 last? ›Most people with COVID-19 get better within a few days to a few weeks after infection, so at least four weeks after infection is the start of when post-COVID conditions could first be identified. Anyone who was infected can experience post-COVID conditions.
How long is COVID contagious for? ›The COVID-19 infectious period can vary, but most people are considered infectious from 48 hours before their symptoms start and can be infectious for up to 10 days.
How do you tell if I have COVID or the flu? ›- Fever.
- Chills.
- Cough.
- Fatigue.
- Sore throat.
- Runny or stuffy nose.
- Muscle pain or body aches.
- Headache Vomiting or diarrhea.
Researchers have discovered that some of the prominent features of a COVID-19 headache include: Having a pulsing, pressing, or stabbing sensation. Occurring bilaterally (across the whole head) Presenting with severe pressure that won't respond to typical pain relievers, like ibuprofen and acetaminophen.
What does mild COVID feel like? ›Many people who are infected have more mild symptoms like a scratchy throat, stuffy or runny nose, occasional mild cough, fatigue, and no fever. Some people have no symptoms at all, but they can still spread the disease.” Fever seems to be one of the more common early markers of COVID-19, Kline noted.
What can I take for COVID? ›
Most people with COVID-19 have mild illness and can recover at home. You can treat symptoms with over-the-counter medicines, such as acetaminophen (Tylenol) or ibuprofen (Motrin, Advil), to help you feel better.
Can COVID affect your neck? ›Both COVID illness and the COVID vaccine can lead to lymph-node swelling, especially in the neck. This swelling isn't dangerous, but it can last a few weeks. Swollen lymph nodes can be a sign of more serious medical conditions, like cancer.
What are some unusual symptoms of Covid-19? ›- Digestive symptoms. COVID-19 might cause nausea, vomiting or diarrhea — either alone or with other COVID-19 symptoms. ...
- Loss of smell or taste. ...
- Skin changes. ...
- Confusion. ...
- Eye problems.
| Symptom | COVID-19 | Cold |
|---|---|---|
| Fever | Usually | Sometimes |
| Diarrhea | Sometimes | Never |
| Nausea or vomiting | Sometimes | Never |
| New loss of taste or smell | Usually (early — often without a runny or stuffy nose) | Sometimes (especially with a stuffy nose) |
Reinfection with the virus that causes COVID-19 means a person was infected, recovered, and then later became infected again. After recovering from COVID-19, most individuals will have some protection from repeat infections. However, reinfections do occur after COVID-19.
Can you go out if you have Covid? ›If you have symptoms of a respiratory infection, such as COVID-19, and you have a high temperature or you do not feel well enough to go to work or carry out normal activities, you are advised to try to stay at home and avoid contact with other people.
What Covid symptoms do dogs get? ›Symptoms of SARS-CoV-2 infection in pets
Most pets who have gotten sick only had mild illness and fully recovered. Some signs of illness in pets may include fever, coughing, difficulty breathing or shortness of breath, lethargy, sneezing, nose or eye discharge, vomiting, or diarrhea.
Green and cloudy: viral or bacterial infection
A lot of the symptoms of viral infections – fever, cough, headache, loss of smell – overlap for COVID-19 and other viral infections like the flu, respiratory syncytial virus and the common cold.
Use medications containing guaifenesin, such as Robitussin, Mucinex, and Vicks 44E. keeping you from getting rest. Coughing is useful because it brings up mucus from the lungs and helps prevent bacterial infections. People with asthma and other lung diseases need to cough.
When does COVID get worse? ›A person may have mild symptoms for about one week, then worsen rapidly. Let your doctor know if your symptoms quickly worsen over a short period of time.
How to get through COVID faster? ›
- Keep a daily routine, such as taking a shower and getting dressed.
- Take breaks from COVID-19 news and social media.
- Eat healthy meals and drink plenty of fluids.
- Stay physically active.
- Get plenty of sleep.
- Avoid use of drugs, tobacco and alcohol.
If you have a severe illness or a weakened immune system, you can be contagious for up to 3 weeks. If you've been fully vaccinated against COVID-19, you may only be contagious for a few days, even if you have a weakened immune system.
How long do COVID symptoms last for vaccinated? ›Side effects generally go away in a few days. Even if you don't experience any side effects, your body is building protection against the virus that causes COVID-19. Adverse events (serious health problems) are rare but can cause long-term health problems. They usually happen within six weeks of getting a vaccine.
How long do you test positive after COVID? ›After a positive test result, you may continue to test positive for some time after. You may continue to test positive on antigen tests for a few weeks after your initial positive. You may continue to test positive on NAATs for up to 90 days.
How long does it take to recover from COVID? ›On average, COVID-19 patients with mild symptoms should begin to see improvement after two weeks. Those with more severe symptoms may feel unwell for up to six weeks. Of course, the recovery period can differ from person to person.
What does a positive COVID test look like? ›A POSITIVE result must show BOTH a BLUE line and a PINK line near the BLUE line. Look closely! Even a very faint, pink Test Line and a blue Control Line is a POSITIVE result. The intensity of the lines may vary.
Can you have Covid without a fever or cough? ›Although a fever is a common symptom of this virus, it's still possible to have COVID-19 without a fever, especially within the first few days after being infected. In fact, one study found that just 55.5% of the surveyed COVID-19 patients reported experiencing a fever.
Can sneezing and runny nose be Covid? ›Is Sneezing Really a Symptom of COVID? Although initially not thought to be a prominent COVID-19 symptom, it is often found in people with the omicron variant. The ZOE COVID Study found that sneezing is an increasingly common symptom of COVID-19.
When do COVID symptoms start? ›How soon after exposure to COVID-19 do symptoms appear? The COVID-19 incubation period, which is the time between when a person is exposed to the virus and when their symptoms first appear, ranges from 1 to 14 days. Most people develop symptoms 5 to 6 days after being in contact with a person with COVID-19.
Where is a COVID headache located? ›Headache phenotypes identified with COVID-19 are largely migraine, tension-type headache, or cough headache located in the frontotemporal or occipital region with wavering intensity and essentially of acute onset.
Can you have COVID and test negative? ›
A negative result means it's likely you are not infectious. But a negative test is not a guarantee you do not have COVID-19 and there's still a chance you may be infectious. You should follow advice on how to avoid catching and spreading the virus.
Will COVID dizziness go away? ›COVID dizziness can take weeks to months to fully resolve. You can combat dizzy spells by staying hydrated, slowing down movements, and maintaining a healthy blood sugar level.
Should I take a decongestant if I have COVID-19? ›You may take an expectorant/cough suppressant combination as needed for cough and congestion. Take an antihistamine/decongestant combination for your allergy symptoms and congestion. If you have uncontrolled blood pressure, then you should avoid the decongestant component.
How soon after exposure are you contagious? ›Researchers estimate that people who get infected with the coronavirus can spread it to others 2 to 3 days before symptoms start and are most contagious 1 to 2 days before they feel sick.
What part of the body does coronavirus affect? ›The virus moves down your respiratory tract. That's the airway that includes your mouth, nose, throat, and lungs. Your lower airways have more ACE2 receptors than the rest of your respiratory tract. So COVID-19 is more likely to go deeper than viruses like the common cold.
How do we get infected with Covid? ›- Breathing in air when close to an infected person who is exhaling small droplets and particles that contain the virus.
- Having these droplets and particles land on the eyes, nose, or mouth.
- Touching the eyes, nose, and mouth with hands that have the virus on them.