COVID-19 is a potentially severe viral infection that affects your lungs and airways.
It's caused by a new type of coronavirus
The virus spreads very easily to other people
COVID-19 is now everywhere in the world
Some infected people have no symptoms, but others get very sick, and some people die
Doctors test swabs from your nose or throat to diagnose COVID-19
No medicines cure COVID-19, but some might help people with severe infection, and doctors are always testing additional ones
Vaccines for COVID-19 have been developed and are starting to be given to people in the United States and around the world
COVID-19 is caused by a new type of coronavirus called SARS-CoV-2. Doctors call it new because it hasn't been around before. It recently changed (mutated) from a type of coronavirus that infects bats.
The virus spreads:
Unlike with many respiratory viruses, you can spread the virus that causes COVID-19 before you have any symptoms. If you don't know you have the virus, you can pass it on and not know it.
There are hundreds of different coronaviruses that are all related. Most of them infect only animals.
Many people with COVID-19, particularly children, have almost no symptoms.
If you do get symptoms, you'll likely have:
You may also have:
A bad infection gets deep in your lungs, causing viral pneumonia. That will make you very short of breath. A bad infection can also affect a lot of organs, including your brain, heart, and kidneys.
You can die from COVID-19. The older you are, the higher your risk of death. Most deaths occur in people over 50 years old. People over 80 are at very high risk. But even children and young adults can die.
You're also at higher risk if you have other medical problems such as heart disease, obesity, or diabetes.
The most common test uses:
The swab is sent to a lab to look for the virus or other evidence of an infection.
A blood test can look for antibodies your immune system has made to defend against the virus. It takes your body a few weeks to make these antibodies, so this test is not useful when you first get sick. But it can help tell whether you were ever infected.
If you're short of breath, doctors will usually:
If you have a mild or moderate case, you'll:
If you have a severe case, with breathing problems, you'll need to go to the hospital. Doctors will:
You may need to be on a ventilator for up to a few weeks.
There are no medicines that are proven to kill the virus, but doctors are trying some that might help.
If you have problems with your kidneys, you may need dialysis.
The best way to prevent COVID-19 is to avoid being exposed to the virus. People who can spread the virus may not have any symptoms, so you can't tell who has it and who doesn't.
It's important to
These actions also help:
Wash your hands often with soap and water for at least 20 seconds
Use an alcohol-based hand sanitizer
Avoid touching your eyes, nose, and mouth with unwashed hands
Cover a cough or sneeze with a tissue, then throw the tissue in the trash
Use a household disinfectant spray or wipe to clean things people touch a lot, like door handles, phones, remote controls, and countertops
To help prevent the virus from spreading, certain people should stay away from other people by quarantining or isolating. If you have symptoms of COVID-19, tested positive for COVID-19, or are a "close contact" of someone with COVID-19, you need to isolate or quarantine.
You are a close contact if you
Were within 6 feet of an infected person (with or without a mask) for at least 15 minutes, including the 2 days before that person showed symptoms or had a positive test for COVID-19
Provided care at home to someone sick with COVID-19
Had direct physical contact with the sick person (hugged or kissed them)
Shared eating or drinking utensils
Were in range of the sick person's respiratory droplets (for example, through a sneeze or cough)
Quarantine is for people who are close contacts. Close contacts may not know if they have the virus or not, because the virus can take 14 days to make you sick or show up in a test. The goal of quarantine is to keep close contacts away from other people until those 14 days are over. If you are a close contact, you need to quarantine for 14 days even if:
You do not need to quarantine after a close contact if you have had COVID-19 in the past 3 months or been fully vaccinated in the past 3 months.
Isolation is for people with COVID-19. If you were a close contact but then you got symptoms or tested positive, you need to isolate. Any days you spent in quarantine don't count for any of the 10 days (at least) you now need to isolate. You should isolate if you:
Isolation can generally end 10 days after your symptoms started, as long as you don't have a fever and aren't taking drugs to lower a fever and your symptoms are getting better. If you never had symptoms, you can stop isolating 10 days after the date of your first positive test.
Why do people who might not even have the virus need to quarantine for 14 days, but people who actually have COVID-19 may only need to isolate for 10 days?
Before you have symptoms or test positive, you can be contagious (able to spread the virus). It can take up to 14 days after you're exposed to the virus for it to make you sick or show up in a test (called the incubation period). That's why you need to isolate for 14 days, even if at the end it turns out that you never had the virus at all. There was no way to know that you weren't contagious until the 14 days were over.
Once you're sick with or test positive for COVID-19, the 14-day period doesn't matter anymore. No matter how many days you were already quarantined (0 to 14 days), once you know you have COVID-19, you start the 10-day isolation clock. Scientists have learned that you most likely are not contagious after 10 days from when you first felt sick or tested positive (unless you still have a fever).
Contact tracing is when health departments look for people who came into contact with someone who has certain infections, including COVID-19. Contact tracers tell you that you may have been exposed to someone with COVID-19, help you get tested, and talk to you about isolating or quarantining. Cooperating with contact tracers helps slow the spread of COVID-19 in the community.
Vaccines for COVID-19 have been developed and are being given to people around the world. Three of these vaccines are being given to people in the United States. The vaccines are known by the name of the company making the vaccine:
The Pfizer-BioNTech vaccine is for people 16 years and older and is given as 2 shots about 3 weeks apart.
The Moderna vaccine is for people 18 years and older and is given as 2 shots about 4 weeks apart.
The Janssen vaccine (also known as the Johnson & Johnson vaccine) is for people 18 years and older and requires only a single shot.
The Pfizer-BioNTech and Moderna vaccines cannot be mixed, meaning you must receive the same manufacturer's vaccine for both shots. You should not get the vaccine if you've had a severe allergic reaction to a previous dose of the vaccine or to any ingredient in the vaccine.
All 3 vaccines completely prevented serious complications of COVID-19 including hospitalizations and deaths in their clinical trials.
Some people may have mild side effects to the vaccines including:
Side effects typically last several days. For the Pfizer-BioNTech and Moderna vaccines, more people experience side effects after the second dose than after the first dose.
There is a small chance of having a severe allergic reaction. This usually happens within a few minutes to 1 hour after getting a dose of the vaccine and requires emergency treatment (call for emergency medical care [911 in the United States] or go to the nearest hospital). Signs of a severe allergic reaction include: