Facts About COVID-19 and the Vaccines

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What is COVID?

COVID is an infectious disease.

There’s no way to know how COVID will affect you. Most people have a mild case, but it can cause serious illness and death.

Some people develop Long COVID, where they have symptoms that last for weeks or months.

COVID can even cause some people to develop new health conditions, such as:

  • Diabetes
  • Heart conditions
  • Blood clots
  • Neurological conditions that affect the brain and nervous system

Why is vaccination so important?

Getting and staying up to date with your COVID vaccine can reduce the risk that you’ll:

  • Get seriously ill, need hospital care, or die from COVID.
  • Develop Long COVID.
  • Spread the disease to others, putting their health and lives at risk.

Who is more likely to get Long COVID?

Anyone who gets sick with COVID can develop Long COVID. Researchers are working to better understand why some people do and some people don’t develop Long COVID.

So far, studies have found that the following people may be more likely than others to get Long COVID:

  • People who get severely ill from COVID, especially those who need hospital care
  • People who have underlying health conditions
  • People who aren’t vaccinated against COVID
  • People who experience multisystem inflammatory syndrome (MIS) during or after COVID illness
  • People who have COVID more than once

What are the symptoms of Long COVID?

People who have Long COVID can experience a variety of symptoms, some of which may be hard to explain. Commonly reported symptoms include:

  • Tiredness or fatigue that interferes with daily life
  • Symptoms that get worse after physical or mental effort (also known as “post-exertional malaise”)
  • Fever
  • Difficulty breathing or shortness of breath
  • Cough
  • Chest pain
  • Fast-beating or pounding heart (also known as heart palpitations)
  • Difficulty thinking or concentrating (sometimes referred to as “brain fog”)
  • Headache
  • Sleep problems
  • Dizziness when you stand up (lightheadedness)
  • Pins-and-needles feelings
  • Change in smell or taste
  • Hair loss
  • Depression or anxiety
  • Diarrhea
  • Stomach pain
  • Joint or muscle pain
  • Rash
  • Changes in menstrual cycles

Getting vaccinated

Who should get a COVID vaccine?

Everyone 6 months or older in the United States should get and stay up to date with their COVID vaccine.

It’s especially important for the following people to get and stay up to date with their COVID vaccine because they’re at increased risk for severe illness from COVID:

  • People 50 and older
  • People who live in long-term care settings
  • People with certain medical conditions
  • Pregnant and recently pregnant people

Where can I find COVID vaccines?

You can find vaccines near you at vaccines.gov.

How are COVID vaccines given?

The available COVID-19 vaccines are given as a shot in the upper part of your arm. Infants and toddlers may receive vaccines in their thighs.

The process is quick and practically painless, because the needle is very thin and the dose is small.

How many vaccine doses do I need for the best protection? And when do I get them?

The number of doses you need to stay up to date with your COVID vaccine and when to get them depend on two things:

  • Your age 
  • Whether you have certain health conditions

Talk to your vaccine or health care provider about when you need to get a COVID vaccine dose.

Vaccine safety

Are COVID vaccines safe?

Yes. The COVID vaccines available in the United States meet the FDA’s and CDC’s very high safety standards.

Hundreds of millions of people in the United States have safely received COVID vaccines under the most intense safety monitoring in U.S. history.

Serious side effects and allergic reactions are very rare, occurring in only a small number of people.

There is no evidence that COVID vaccines will cause long-term health problems, such as infertility or cancer.

COVID is a greater threat to you than any risk from vaccine side effects.

COVID can leave you with heart and lung damage and other conditions that require long-term treatment.

If you’re allergic to any ingredients in the vaccines, your vaccine or health care provider can help you decide if it’s safe for you to get a COVID vaccine.

Are COVID vaccines safe for children?

COVID vaccines were rigorously tested in thousands of children before authorization by the FDA. They were shown to be safe and effective during the clinical trials. And real-world evidence from vaccinating millions of children confirms their safety.

Children had the same kinds of temporary side effects from vaccines as adults. Side effects during the clinical trials were usually mild and went away on their own in a few days.

What safeguards are in place to make sure COVID vaccines are safe?

Before the FDA makes vaccines available to the public:

  • Scientists must test the vaccines in medical studies, called clinical trials, with thousands of participants. These studies compare what happens to people who get the vaccine with people who don’t get the vaccine.
  • More than 100,000 volunteers from diverse populations took part in clinical trials for the available COVID vaccines.
  • FDA scientists review the data from the medical studies and inspect the places where the vaccines are made before they authorize or approve the vaccines for public use.
  • Even after vaccines are available to the public:
  • FDA and CDC scientists closely monitor how the vaccines are made and given, to identify any safety issues.
  • FDA and CDC scientists closely review any reports of side effects or reactions and share these facts with the public.

How can COVID vaccines be safe? They were developed so fast.

COVID may be a new disease, but vaccines aren’t new.

Scientists were able to quickly develop safe, effective COVID vaccines by applying many years of vaccine experience and advances in technology.

Also, the National Institutes of Health had been working on a coronavirus vaccine before the pandemic and was able to use that experience in developing a COVID vaccine.

Importantly, no one cut any corners or skipped any steps that affect vaccine safety in the development, testing, authorization, and approval of COVID vaccines.

Will the shot make me sick?

You can’t get COVID from the vaccines because they don’t contain the virus that causes the disease.

Your arm might feel sore after you get your shot. You might also experience flu-like symptoms, such as fever, headaches, body aches, and tiredness.

These are normal signs that your immune system is responding to the vaccine. Although these side effects may be unpleasant, you’re not actually sick. And they last a few days at most.

What are the more serious side effects of COVID vaccines?

Serious side effects from any vaccine, including the COVID vaccines, are very rare.

It’s also highly unlikely that the vaccines will cause any long-term health problems, such as cancer.

A very small proportion of vaccinated people have experienced the following in the hours and days after vaccination with one or more of the vaccines:

  • Anaphylaxis—an allergic reaction that, if it happens, is likely to occur within minutes of vaccination. Vaccination sites are prepared to handle any rare cases of anaphylaxis that occur.
  • Myocarditis and pericarditis—two kinds of heart inflammation that, if they happen, are likely to occur within several days of vaccination.
  • Guillain-Barré syndrome—a rare autoimmune disorder that, if it happens, is likely to occur within the first couple of weeks after vaccination.
  • Thrombosis with thrombocytopenia syndrome—an extremely rare blood-clotting condition that, if it happens, is likely to occur within the first couple of weeks after vaccination. Importantly, the type of vaccine associated with this rare condition is no longer available in the United States.

If any of these unlikely reactions happen, health care providers know how to treat them.

The fact that we know of these extremely rare cases shows that the FDA's and CDC’s vaccine safety monitoring systems work and catch even the rarest reactions.

Are COVID vaccines safe for people who are pregnant, want to become pregnant, or are breastfeeding?

Yes. Getting a COVID vaccine can protect you against severe illness from COVID and help keep your baby safe.

COVID can be a dangerous disease during pregnancy and increases the risk of preterm birth. It might increase risks for other adverse pregnancy outcomes.

Vaccination against COVID does not lead to complications during pregnancy.

There’s also no evidence that any vaccines, including COVID vaccines, cause fertility problems in women or men.

And there’s no reason to put off getting vaccinated if you’re on your period.

CDC recommends COVID vaccination as soon as possible for all people who are pregnant, trying to become pregnant, wanting to become pregnant someday, or breastfeeding.

How do COVID vaccines work?

The COVID vaccines available in the United States introduce your immune system to the spike protein found on the surface of the coronavirus.

Your immune system sees the spike protein as an invading germ and reacts by creating cells that will be ready to identify and attack the coronavirus if you’re exposed to it. 

The vaccines don’t contain the coronavirus, so you can’t get COVID from them.

Once your immune system is introduced to the spike protein, your body breaks down the vaccine ingredients and gets rid of them.

At no point do the vaccines change or interact with your DNA.

Vaccine effectiveness

How effective are COVID vaccines?

All available COVID vaccines are effective at preventing severe illness, hospitalization, and death due to COVID.

For the best protection, you need to stay up to date with your COVID vaccine.

Why should I get and stay up to date with my COVID vaccine if I can still get infected with COVID?

COVID vaccines work best to prevent severe illness, hospitalization, and death due to COVID.

If you’re up to date with your COVID vaccine and the virus enters your body (infects you), your immune system will quickly recognize the virus and will work to keep it from doing real harm.

Will COVID vaccines prevent me from infecting others?

If you stay up to date with your COVID vaccine, you’re less likely to get and spread COVID.

If you’re exposed to someone with COVID or if you get COVID, there are things you can do to prevent spreading COVID. These include:

  • Keeping your distance from other people
  • Wearing a high-quality mask if you must be around others at home or in public