COVID-19 Vaccine Overview

Vaccines are important public health tools that can prevent many different bacterial and viral infections. The use of vaccines has prevented countless cases of infections, preventing suffering and saving millions of lives. Below is some information you should know about vaccines, the COVID-19 vaccines, and general resources about vaccinations in IBD. 


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Importance of vaccines | COVID-19 vaccine safety | mRNA vaccines |
Viral vector vaccines | Herd immunity | Vaccines and medicationsPatient guidance 

The importance of vaccines

Vaccines help activate the body’s natural defenses. When you go to the doctor and have a vaccine, your body launches an attack to fight the infection. For example, if you were exposed to the flu, the vaccine reduces the risk of future infection. If you are exposed to an infection-causing agent after receiving a vaccine, your body’s immune system is “primed” to fight off the infection. 

There are many different types of vaccines. Some vaccines are made of a weakened live virus. The weakened live virus does not cause infection, but does cause the body to react and cause immunity to protect against future infections if exposed to the virus. Examples of this type of vaccine include the chickenpox or measles, mumps, and rubella (MMR) vaccines.   

All other vaccines are inactivated and made from a part of a bacteria or virus, such as the hepatitis B vaccine. Many vaccines include something that further stimulates the immune system to develop antibodies—this is called an adjuvant. The inactive shingles vaccine is an example of a vaccine that includes an adjuvant. Some vaccines can be administered by mouth or sprayed into the nose, but most are given by injection. The COVID-19 vaccines currently available for use are mRNA and viral vector vaccines.


Will the COVID-19 vaccines be evaluated for safety?

COVID-19 vaccines can be administered to patients with underlying health conditions, including inflammatory bowel disease. Patients should discuss any risks or contraindications (such as known serious allergic reactions to other types of vaccines) with their doctor. Note, that the COVID-19 vaccines currently in use within the U.S. are inactivated. 

The mRNA vaccines are being held to the same rigorous safety and effectiveness as all other types of vaccines in the United States. The only COVID-19 vaccines that the U.S. Food and Drug Administration (FDA) will make available for use in the United States (by approval or emergency use authorization) are those that meet these standards. To learn more about the approval and emergency use authorizations please visit our Vaccine Information page.  

Continued monitoring of the vaccine is very important. For information on COVID-19 vaccine monitoring in IBD, click here. 

About mRNA vaccines

The COVID-19 vaccines are mRNA vaccines. While it may feel like the COVID-19 vaccines were developed fast, it’s important to know that mRNA vaccines have been studied for years. There are currently no licensed mRNA vaccines in the United States. However, researchers have been studying and working with them for decades. Interest has grown in these vaccines because they can be developed in a laboratory using readily available materials. This means the process can be standardized and scaled up, making development of this type of vaccine faster than traditional methods. 

Vaccines based on mRNA were studied before for many different infections including flu, Zika, rabies, and cytomegalovirus (CMV). As soon as the necessary information about the virus that causes COVID-19 (SARS-Cov-2) became available in January 2020, scientists began designing the mRNA instructions for cells to build an mRNA vaccine. 

How do COVID-19 mRNA vaccines work?

Vaccines based on mRNA provide a code that tells our cells to make a protein that is recognized by our immune system and harmless to people. COVID-19 mRNA vaccines give instructions for our cells to make a harmless piece of “spike protein.” The spike protein is found on the surface of the virus that causes COVID-19.  

COVID-19 mRNA vaccines are given in the upper arm muscle. Once the instructions (mRNA) are inside, the cells use them to make the protein piece. After the protein piece is made, the cell breaks down the mRNA and gets rid of them. 

Next, the cell displays the protein piece on its surface. Our immune systems recognize that the protein doesn’t belong there, and begin building an immune response and making antibodies, like what happens in natural infection response against COVID-19. 

At the end of this process, our bodies have learned how to protect against future infection. The benefit of mRNA vaccines, as with all vaccines, is that those vaccinated gain this protection without having to risk the serious consequences of getting sick with COVID-19. 

How many doses of the mRNA vaccines are given?

They are given initially as a series of two injections, with a specific number of  weeks between the first and second dose.

  • Pfizer-BioNTech vaccine second dose is given 21 days after the first dose
  • Moderna vaccine second dose is given 28 days after the first dose

The CDC and ACIP have updated recommendations that patients who are immunesuppressed receive an additional dose of the mRNA vacccines at least 28 days after their second dose. The Foundation is aware of the FDA and CDC updates and supportive of patients with IBD getting an additional dose if they are on immune therapies. We also want to reassure the IBD population that the available data at this time from multiple studies show the vast majority of patients are able to mount an immune response post immunization and do not show that our patients who are vaccinated are at increased risk of infection or hospitalization. Current data shows that IBD patients are not inherently at increased risk for severe illness from the COVID-19. Click here to read the Foundation's position on an additional dose.

What are the common side effects? 

These vaccines have been tested in about 30,000 volunteers during clinical studies. Many participants experienced pain and redness where the vaccine was injected. Some had fevers, headaches, and muscles aches. The reactions appear to occur more with the second dose. It is important to recognize that these side effects indicate that the immune system is making a response. You are encouraged to talk to your healthcare provider about what to expect after being vaccinated, including frequently experienced side effects. 

Facts about COVID-19 mRNA vaccines

They cannot give someone COVID-19

  • mRNA vaccines do not contain the live virus that causes COVID-19. 

They do not affect or interact with our DNA in any way

  • mRNA never enters the nucleus of the cell, which is where our DNA (genetic material) is kept. 

  • The cell breaks down and gets rid of the mRNA soon after it is finished using the instructions. 

mRNA vaccines cannot cause or exacerbate IBD 

  • No prior vaccine has been shown to cause or exacerbate inflammatory bowel disease. 

What are viral vector vaccines?

According to the Centers for Disease Control and Prevention (CDC), “viral vector vaccines use a modified version of a different virus (the vector) to deliver important instructions to our cells.” In COVID-19 viral vector vaccines, this vector enters cells in our body and produces a spike protein that is found on the surface of the SARS-CoV-2, the virus that causes COVID-19. Once on the surface of the cell, this spike protein triggers the immune system to produce antibodies and other immune cells that protect us from the SARS-CoV-2 virus. 

The benefit of this and other COVID-19 vaccines is that our bodies get this protection without ever having to risk the serious consequences of getting sick with COVID-19. Any temporary discomfort experienced after getting the vaccine is a natural part of the process and an indication that the vaccine is working. 

Johnson & Johnson’s COVID-19 viral vector vaccine received EUA approval in the United States. This vaccine requires only one dose, although an additional phase three trial has been started to observe the effects of two doses of this vaccine.  A rare and severe type of blood clot has been seen in some reported cases in the U.S. 

What are the common side effects? 

Based on data presented and considered by the FDA and Advisory Committee on Immunization Practices (ACIP) from the vaccine clinical trials, the most common side effects of the Johnson & Johnson vaccine may include:  

  • Injection site reaction 

  • Headache 

  • Fatigue 

  • Muscle pain (myalgia) 

A rare and severe type of blood clot has been seen in some reported cases in the U.S. Contact your doctor if you experience symptoms such as severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after vaccination. 



COVID-19 Vaccines for Moderately to Severely Immunocompromised People | CDC

Recommendation to Pause Use of Johnson & Johnson’s Janssen COVID-19 Vaccine | CDC

Joint CDC and FDA Statement on Johnson & Johnson COVID-19 Vaccine | CDC Online Newsroom | CDC

Vaccines and Related Biological Products Advisory Committee February 26, 2021 Meeting Briefing Document- FDA 

Facts about the viral vector COVID-19 vaccine 

This vaccine cannot give someone COVID-19 

  • The viral vector vaccine does not contain the live virus that causes COVID-19. It contains a harmless virus used that is designed so that it does not replicate in the body. 

Do these vaccines interact or affect our DNA? 

  • The genetic code delivered by the viral vector does not combine with a person’s DNA. 

Viral vector-based vaccine cannot cause or exacerbate IBD  

  • No prior vaccine has been shown to CAUSE or EXACERBATE inflammatory bowel disease.  

 Source: Understanding Viral Vector COVID-19 Vaccines | CDC 

What is herd immunity? 

Herd immunity occurs when a large portion of a community (the herd) becomes immune to disease, making the spread of disease from person to person unlikely. As a result, the whole community becomes protected, not just those who are immune. When herd immunity is achieved, even newly born babies are offered protection, as the disease has little opportunity to spread.   

According to the Association for Professionals in Infection Control and Epidemology (APIC), it is not known when herd immunity will happen. Herd immunity will depend on a number of factors including: 

  • How many people develop immunity after a COVID-19 infection 

  • How soon a COVID-19 vaccine is widely available 

  • How many vaccine doses will be available for distribution 

  • How many people get vaccinated  

While we wait for vaccines to become widely available, and eventually for herd immunity to develop, it is essential that we continue to wear masks in public and follow social distancing guidance to slow the spread of COVID-19. 

Vaccine effectiveness and immune-suppressing medications

There is no data to suggest that immune-suppressing medications for Crohn's disease and ulcerative colitis (such as immunomodulators, or biologics) impact COVID-19 vaccine response. Research studies are underway to gain a better understanding of the impact of the COVID-19 vaccine on patients with Crohn’s disease and ulcerative colitis, including side effects, effectiveness, and disease activity. It is important to continue taking prescribed medications and talk to your doctor about any concerns or questions related to your treatment and risk for COVD-19.

If you have IBD and have received a COVID-19 vaccine, you may be able to take part in PREVENT COVID, a research study brought to you by IBD Partners to learn more about how well the COVID-19 vaccine works for IBD patients. Click here to learn more about PREVENT COVID.

Patient guidance: Trust in science and the healthcare system 

There’s a lot of information and opinions on the internet, in social media, and on television. In addition, there is distrust of the U.S. healthcare system and an anti-vaccine movement promoting misinformation about vaccines. Despite this climate of distrust and misinformation, patients and caregivers should be confident in the rigor of clinical trials, the diligence of the FDA and other agencies charged to protect the public.  

Patients and caregivers are encouraged to follow the guidance below: 

  • Seek information from reputable medical organizations that provide specific data and references about the vaccine 

  • Avoid message boards, blogs, or other websites that may be vague about information sources

  • Extreme language - either positive or negative - about the COVID-19 vaccine is probably incorrect 

If you are concerned or confused about a story or article, consider taking the following steps to ensure its accuracy:

  1. Check to see if the article or story provides references and other credible links where you can learn more  

  1. Check the statistics or number by visiting credible sites like the NIHCDC or FDA, or medical journals including Crohn’s & Colitis 360 

  1. Call the IBD Help Center—we are here to help address your questions and concerns 

  1. Talk to your healthcare provider 

Remember, your healthcare providers are dedicated to diagnosing, treating, healing and improving your quality of life. Talk to your healthcare provider and engage in conversations where you can discuss any concerns about vaccinations. You can learn more about effective partnering and communicating with your healthcare team by visiting: 



Last updated October, 2021