Getting immunized against COVID-19 will keep most people from getting sick. Even in a rare case where one does catch the virus, the vaccine will likely prevent you from becoming seriously ill.

Protecting yourself also protects the people around you, like those at increased risk of severe illness from COVID-19 or those who can’t get vaccinated — like infants, or people with weakened immune systems from things like chemotherapy for cancer.

We are still learning how the vaccine affects whether people can still transmit COVID-19 to others. It may be possible that a vaccinated person can still carry the virus and infect others, even if that person does not appear to be sick.

That’s why, until enough Americans are vaccinated to fight off COVID-19, we will need to keep wearing masks, stay 6 feet apart from people we don’t live with, avoid crowds, and wash our hands frequently.

Researchers began developing vaccines for COVID-19 in January 2020, based on decades of understanding immune response and how vaccines work. Thousands of volunteers participated in clinical trials that started that spring, making sure we can trust the vaccines to be safe and effective.  

Based on the results, the U.S. Food and Drug Administration (FDA) has authorized multiple vaccines for public use in December 2020 and a third in February 2021. The vaccines met the agency’s rigorous and science-based standards for quality, safety, and effectiveness.  

COVID-19 is a new virus requiring new vaccines, but vaccines have been saving lives and protecting us for centuries. Now, medical experts believe COVID-19 vaccines can help us move forward in our everyday lives. 

Every vaccine must go through rigorous testing and inspection to ensure it is safe. Vaccines for COVID-19 followed a 3-phase process  where there are several stages before FDA authorization: 

Phase 1: The vaccine is tested in a small number of  generally healthy adults, usually between 20 and 80  people. It’s evaluated for safety, dosage, and any side  effects. Experts also look at what type of immune  response is created. 

Phase 2: If there are no safety concerns from Phase  I studies, the vaccine is given in various dosages to  hundreds of adults who may have a variety of health  issues and come from different backgrounds to make  sure it is safe. These studies provide additional safety  information on common short-term side effects and  risks, examine the relationship between the dose  given and the immune response, and may provide  initial information regarding the effectiveness of the  vaccine. 

Phase 3: Experts broaden the study to include  thousands of adults, from a variety of ages and  backgrounds. They see how many people who got the  vaccine were protected from the disease, compared  to those who received a placebo. 

Researchers made sure that the trials included  adults of diverse backgrounds, races, ethnicities,  and geographic areas. They collaborated with faith  leaders, community organizations, and health clinics  to reach volunteers from many different walks of life  across the United States. 

Medical experts and doctors want to make sure the  vaccines work safely and effectively for as many  people as possible. People may respond differently  to vaccines based on factors like age, gender, and  health conditions — so it is important to have a  diverse group of participants in clinical trials. 

COVID-19 has hit hard in the Black and Hispanic  communities. Historically, these populations haven’t  always been included in clinical research, but with COVID-19 vaccines researchers made sure  volunteers included people of color, as well as  people over the age of 65 who are at higher risk of  complications from the virus.

At this time, the studies do not include pregnant women or young children, but testing with those groups will likely begin in the near future. Pregnant women who get infected with COVID-19 disease are more likely to have severe disease. 

People who are pregnant and part of a group recommended to receive COVID-19 vaccine, such as healthcare personnel, may choose to be vaccinated. A conversation between pregnant patients and their clinicians may help them decide  whether to get vaccinated.

Immunization against COVID-19 will help protect you for the near future, but it’s still not clear how long the protection will last. We will have a clearer picture of how long immunity lasts in years to come when we have collected more data. Both natural immunity and immunity from the vaccine are important ways to fight COVID-19 that experts are trying to learn more about, and places like the CDC will keep the public informed as new evidence becomes available. 

Yes. mRNA vaccines have been in development for years and have been proven to be safe and effective. They build immune protection by copying the shape of the virus without actually including a piece of the virus itself. 

mRNA stands for messenger ribonucleic acid and can most easily be described as instructions for how to make a protein, or even just a piece of a protein. 

mRNA is not able to alter our genetic makeup (DNA). 

The mRNA from a COVID-19 vaccine does not affect or interact with our DNA in any way. Instead, COVID-19 vaccines that use mRNA work with the body’s natural defenses to safely develop immunity to disease.

It’s normal to experience some mild discomfort following a vaccine. This means it’s working and creating an immune response in your body. 

You may feel soreness or experience some swelling  in your arm. You may also feel tired, have a headache,  fever, or chills. These symptoms do not mean you  have COVID-19 — it’s not possible to get COVID-19  from the vaccine. 

These symptoms may impact your daily activities,  but they shouldn’t last more than 2-3 days. If they  continue or get worse, call your doctor, nurse, or  clinic. 

Even if you have these types of effects after your first  shot, it’s important to make sure you get the second  one, unless a vaccination provider or your doctor tells  you not to get a second shot. Ask your doctor if you have questions. Your body takes time to build  immunity. You may not be fully protected against  COVID-19 until 1-2 weeks after your second shot. 

In most cases, discomfort from fever or pain is  normal. Contact your doctor or healthcare provider: 

• If the redness or tenderness where you got the  shot increases after 24 hours 
• If your symptoms are worrying you or do not  seem to be going away after a few days 
• If you get a COVID-19 vaccine and you think you  might be having a severe allergic reaction after leaving the vaccination site, seek immediate medical care by calling 911. Learn more about  COVID-19 vaccines and rare severe allergic reactions. 

People with underlying medical conditions can receive  the FDA-authorized COVID-19 vaccines. In fact,  vaccination is especially important for adults of any  age with certain underlying medical conditions, like  diabetes and high blood pressure, because they are at  increased risk for severe illness from COVID-19. Ask your doctor if you have specific questions.

People with autoimmune conditions may receive an mRNA COVID-19 vaccine. However, they should consult with their doctor, nurse or other health provider to discuss whether to get a COVID-19 vaccine. 

When we get a vaccine, it activates our immune response. This helps our bodies learn to fight off the  virus without the danger of an actual infection. If we are exposed to the virus in the future, our immune system “remembers” how to fight it. 

Some COVID-19 vaccines use messenger RNA, or mRNA. mRNA vaccines do not contain a live virus — they give our bodies “instructions” for how to make and fight the harmless spike-shaped proteins that will protect against a COVID-19 infection. While these vaccines use new technology, researchers have been studying them for decades. 

Medical experts do not know exactly what percentage of people would need to get vaccinated to achieve herd immunity to COVID-19. Herd immunity is a term used to describe when enough people have protection — either from previous infection or vaccination — that  

it is unlikely a virus or bacteria can spread and cause disease. As a result, everyone within the community is protected even if some people don’t have any protection themselves. The percentage of people who need to have protection in order to achieve herd immunity varies by disease.

Many teams of medical experts around the world have helped in the search for a safe and effective COVID-19 vaccine — including many of the leading doctors here in the United States. 

Having multiple vaccines in development and production is crucial so that vaccination programs can be rolled out in many different countries at the  same time, reaching as many people as possible. 

Hundreds of millions of vaccine doses have already  been distributed and hundreds of millions more are  in production. New vaccine candidates are also in  development which may provide more options, as  well as additional quantities for the American people.

Many vaccines work with harmless pieces of the  spike-shaped proteins on the outer shell of the virus,  instead of the entire virus. These proteins aren’t  infectious — our immune system recognizes that the  virus’ proteins in the vaccine don’t belong in our body  and learns how to fight them off. 

Messenger RNA (mRNA) vaccines teach our body  how to make the harmless protein pieces and protect  us from the viruses that contain them. This produces  antibodies, which are part of our body’s immune  system defenses, that fight off the virus if it enters  our bodies. It’s important to note that mRNA vaccines  help build protection to a very specific type of protein  and do not interact with our DNA in any way. 

State and local governments will ultimately decide  when each group gets access to vaccines based on  the local supply. That way, communities can set the priorities that work for them. The federal government  does not mandate vaccines or set the rules for each  community. 

As more vaccines are produced over the first half  of 2021, more people will be able to get vaccinated  based on recommendations from the Advisory  Committee on Immunization Practices (ACIP) and  the CDC. 

If you have questions, make sure you talk to your  doctor. Some people — like pregnant women or  people with certain severe allergies — might be told  to wait to get a specific vaccine once it’s available. 

Your doctor should be able to tell you when and  where you can get your shots. It might be at a hospital, the doctor’s office, a pharmacy, or a drive thru clinic.

If you’ve had COVID-19 in the past 90 days, talk to  your doctor about when you should get vaccinated.  People who have already had COVID-19 should  still eventually get vaccinated to ensure they are  protected. 

Over the next few months, with more and more  people getting vaccinated, we will find out more about  how the vaccines protect people who have already  had COVID-19. 

COVID-19 vaccination should be offered to you  regardless of whether you already had COVID-19  infection. You should not be required to have an  antibody test before you are vaccinated. 

However, anyone currently infected with COVID-19  should wait to get vaccinated until after their illness  has resolved and after they have met the criteria to  discontinue isolation.

There shouldn’t be a cost to get vaccinated. Insurance  providers will cover the cost of the vaccine, and the U.S. government has set up a system to cover costs  for those who do not have insurance. 

Vaccine doses bought by the U.S. government will  be given to the public for free, however, vaccination providers will be able to charge an administration fee for giving the shot to someone. Vaccine providers  can get this fee reimbursed by the patient’s public or private insurance company or, for uninsured  patients, by the Health Resources and Services  Administration’s Provider Relief Fund.

New variants of the virus that causes COVID-19  illness have emerged. Current data suggest that  COVID-19 vaccines used in the United States  should work against these variants. For this reason,  COVID-19 vaccines are an essential tool to protect  people against COVID-19, including against new variants. CDC recommends getting vaccinated as  soon as a vaccine is available to you.

If you’re fully vaccinated, you can safely resume many  activities without having to wear a mask or stay six  feet away from others—unless required by federal,  state, local, tribal, or territorial laws or regulations, including business and workplace guidance. 

If you travel, you should still take steps to protect  yourself and others. You must still wear a mask  on planes, buses, trains, and other forms of public  transportation traveling into, within, or out of the  United States, and in U.S. transportation hubs such as  airports and stations. 

CDC is continuing to update guidelines as more  information becomes available, so please visit their website for the latest recommendations.

We need to work together to get to the end of this  pandemic. 

While trial data suggests authorized COVID-19  vaccines are highly effective, we will only manage the  pandemic if enough people take them. 

Vaccine manufacturers are producing and distributing  millions of doses of the vaccines, but they won’t all  be available at once. That’s why certain high-risk  groups are getting them first. 

Healthcare workers, seniors in long-term care  facilities, frontline workers, and individuals over the  age of 75 are the most vulnerable and will be able  to get the vaccine first in most states. More doses  will be available to other groups in the spring as the  supply increases. 

Until enough people have been immunized against  COVID-19, we should continue wearing masks,  staying 6 feet apart from people we don’t live with,  avoiding crowds, and washing our hands.