How Does the COVID-19 Vaccine Work? – Washington State Department of Health

What's the difference between the Comirnaty and Pfizer-BioNTech COVID-19 vaccines?

Comirnaty and Pfizer-BioNTech are actually the same vaccine. Before the Food and Drug Administration (FDA) approves a vaccine, it's known by the company that created it (Pfizer). Once the FDA granted approval, Pfizer chose a brand name for the vaccine (Comirnaty).

In November 2021, Pfizer released an updated formula of the Comirnaty COVID-19 vaccine. The update allows providers to administer the vaccine without using a diluent. Providers can still use any remaining vials of the formulation for people 12 years and older. Children 5 to 11 years old may only get the pediatric formula of the vaccine.

For full approval, the FDA evaluates data over a longer period of time than for an emergency use authorization. For the vaccine to be given full approval, the data must show a high level of safety, effectiveness, and quality control in vaccine production. The purpose of emergency use authorization is to ensure that people can get lifesaving vaccines prior to a longer-term analysis of data. However, EUA still requires a very thorough review of clinical datajust over a shorter period of time.

Three vaccines are authorized for emergency use or fully approved by the U.S. Food and Drug Administration (FDA). These vaccines are currently offered in Washington state.

The COVID-19 vaccine teaches your immune system to recognize the coronavirus. When you get the vaccine, your immune system makes antibodies (fighter cells) that stay in your blood and protect you in case you are infected with the virus. You get protection against the disease without having to get sick.

When enough people in the community can fight off the coronavirus, it has nowhere to go. This means we can stop the spread quicker and get a little closer to ending this pandemic.

This short video explains how COVID vaccines are made.

A messenger RNA, or mRNA vaccine is a new type of vaccine. mRNA vaccines teach your cells how to make a harmless piece of the spike protein. The spike protein is what you see on the surface of the coronavirus. Your immune system sees that the protein doesn't belong there and your body will start to build an immune response and make antibodies. This is similar to what happens when we naturally get a COVID-19 infection. Once it does its job, the mRNA quickly breaks down and the body clears it away in a few days.

Although we have used mRNA for other types of medical and veterinary care in the past, creating vaccines using this method is a huge leap forward in science and may mean future vaccines can be created more easily.

You may read more about how mRNA vaccines work on CDC's website, or watch this video from Dr. Paul Offit at the Children's Hospital of Philadelphia.

This type of vaccine uses a weakened version of a different virus (the vector) that gives your cells instructions. The vector enters a cell and uses the cell's machinery to create a harmless piece of the COVID-19 spike protein. The cell displays the spike protein on its surface, and your immune system sees that it doesn't belong there. Your immune system will start to make antibodies and activate other immune cells to fight off what it thinks is an infection. Your body learns how to protect you against future infection with COVID-19, without you having to get sick.

Like other routine vaccines, the most common side effects are a sore arm, fatigue, headache, and muscle pain.

These symptoms are a sign that the vaccine is working. In the Pfizer and Moderna trials, these side effects occurred most often within two days of getting the vaccine, and lasted about a day. Side effects were more common after the second dose (of the initial two-dose series) than the first dose. In the Johnson & Johnson clinical trials, side effects lasted an average of one to two days.

For all three vaccines, people over age 55 were less likely to report side effects than younger people.

Clinical trials found that approximately:

You may see some rumors about untrue side effects online or on social media. Make sure any time you see a claim about a side effect that you check the source of that claim. This video can teach you more about how to figure out if a claim online is true or not.

The ingredients in the COVID-19 vaccines are pretty typical for vaccines. They contain the active ingredient of mRNA or modified adenovirus along with other ingredients like fats, salts, and sugars that protect the active ingredient, help it work better in the body, and protect the vaccine during storage and transport.

Pfizer, Moderna, and Johnson and Johnson vaccines do not contain human cells (including fetal cells), the COVID-19 virus, latex, preservatives, or any animal by-products including pork products or gelatin. The vaccines are not grown in eggs and do not contain any egg products.

See this Q&A; webpage from the Children's Hospital of Philadelphia for more information about ingredients. You can also find the full ingredients lists in the Pfizer, Moderna, and Johnson & Johnson fact sheets.

The Johnson & Johnson COVID-19 vaccine was created using the same technology as many other vaccines. It does not contain parts of fetuses or fetal cells. One piece of the vaccine is made in lab-grown copies of cells that originally came from elective abortions that took place over 35 years ago. Since then, the cell lines for these vaccines have been maintained in the lab and no further sources of fetal cells are used to make these vaccines. This might be new information for some people. However, vaccines for chickenpox, rubella and hepatitis A are made in the same way.

This is a myth circulated online by non-scientific sources. There is no evidence that any vaccine affects fertility, including COVID-19 vaccines.

The vaccine is safe and effective. The Centers for Disease Control and Prevention (CDC), American College of Obstetricians and Gynecologists (ACOG), and Society for Maternal-Fetal Medicine (SMFM) recommend the COVID-19 vaccine for people who are pregnant, lactating, or planning to get pregnant. See Coronavirus (COVID-19), Pregnancy, and Breastfeeding: A Message for Patients for more information. You can also see our FAQ on vaccines and pregnancy.

See the FDA COVID-19 Vaccines webpage for facts about the vaccines. Once additional vaccines are authorized, the FDA will share their information as well.

An EUA allows the FDA to make a product available during a declared state of emergency before it has a full license. Any EUA granted by the FDA is further vetted by the Scientific Safety Review Workgroup, as part of the Western States Pact.

On October 27, Gov. Jay Inslee announced Washington joined other western states to review the safety and efficacy of COVID-19 vaccines once authorized by the FDA. This workgroup will provide another layer of scrutiny and expert review to this process.

The Scientific Safety Review Workgroup includes Washington, Oregon, Nevada, Colorado and California. Inslee announced Washington's representatives to the workgroup on Nov. 9.

The panel includes experts appointed by all member states, and nationally recognized scientists with expertise in immunization and public health. When the FDA authorizes a vaccine for emergency use, the panel reviews all publicly available data concurrently with federal reviews, and presents a report as soon as possible. This process took place for the three vaccines we currently have available in Washington state, and will happen for all COVID-19 vaccines that are granted an Emergency Use Authorization (EUA) in the future. Review usually takes about 1 to 2 days and is completed before the first vaccine shipment arrives in Washington, so it does not delay the process.

Read the findings of the Western States Scientific Safety Review Workgroup:

COVID-19 vaccination commonly comes with side effects, such as sore muscles or a fever. If you have symptoms after getting the vaccine, you may wonder if it's safe to work or go about your tasks safely. Employers may wonder if it's safe for a staff member to return to in-person work. It can take 1-2 weeks after your second shot before you are fully protected so you could still come down with COVID-19 if you are exposed before then. It's also important to remember that each person's immune system works a little differently and the vaccine won't work for approximately 1 in 2,500 people who are vaccinated.

This chart (PDF) helps you understand if you are reacting to the vaccine or if you might need to get tested for COVID-19 and isolate. If you have symptoms in the middle category, you may wish to seek medical care or to wait and see. If your symptoms go away in a day or two, it may have been just a vaccine reaction. If they continue or you feel like you should, seek medical advice. If there's a possibility you have COVID-19 or were exposed, please stay away from others as a precaution.

The vaccine should not be given to people with a known history of severe allergic reaction, such as anaphylaxis, to a previous dose of an mRNA or viral vector vaccine, or to any ingredient of the Pfizer-BioNTech/Comirnaty, Moderna, or Johnson & JohnsonJanssen COVID-19 vaccines.

People who have had a severe allergic reaction to other vaccines or injectable therapies may still be able to receive the vaccine. However, providers should do a risk assessment and counsel them about potential risks. If the patient decides to get the vaccine, the provider should observe them for 30 minutes to monitor for any immediate reactions.

The Advisory Committee on Immunization Practices (ACIP) recommends that providers observe all other patients for at least 15 minutes after receiving the vaccine to monitor for an allergic reaction. See ACIP's interim clinical considerations for mRNA vaccines for more information.

It's normal to have some side effects after getting the vaccine. This can be a sign that the vaccine is working. If you experience a medical emergency after getting the COVID-19 vaccine, call 9-1-1 immediately.

If you get sick after getting the vaccine, you should report the adverse event to the Vaccine Adverse Event Reporting System (VAERS). An adverse event is any health problem or side effect that happens after a vaccination.

For more information about VAERS, see "What is VAERS?" below.

VAERS is an early warning system led by the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA). VAERS can help detect problems that may be related to a vaccine.

Anyone (health care provider, patient, caregiver) can report possible adverse reactions to VAERS.

There are limits to the system. A VAERS report does not mean the vaccine caused the reaction or outcome. It only means that the vaccination happened first.

VAERS is set up to help scientists notice trends or reasons they should investigate a possible problem. It is not a list of verified outcomes of vaccination.

When you make a report to VAERS, you help the CDC and the FDA identify possible health concerns and make sure vaccines are safe. If any issues arise, they will take action and notify health care providers about potential issues.

Viruses mutate (change) as they spread from person to person. A variant' is a mutated strain of virus. Some variants disappear over time and some continue to spread in communities.

The Centers for Disease Control and Prevention (CDC) identifies the virus variants that are concerning. Currently, several variants are concerning because they spread quickly and more easily, causing more COVID-19 infections.

Getting vaccinated helps slow the spread of the virus, and keeps variant strains in check. It also gives you strong protection against hospitalization and death for all known virus variants.

Some vaccinated people may still get infected with a variant strain, but research shows they tend to experience mild symptoms. It's important to get all recommended doses so you have maximum protection against variants.

Vaccination is the best way to protect you, your loved ones, and your community. High vaccination coverage will reduce the spread of the virus and help prevent new virus variants from emerging.

Visit our pages on the COVID-19 variants and vaccine breakthrough for more information.

Death is not the only risk from having COVID-19. Many people who get COVID-19 only have mild symptoms. However, the virus is extremely unpredictable, and we know some COVID-19 variants are more likely to make you really sick. Some people can get very sick or die from COVID-19, even young people with no chronic health conditions. Others, known as COVID long-haulers may get symptoms that last for months and affect their quality of life. We also don't know yet all the long-term effects of COVID-19 since it's a new virus. Getting vaccinated is our best protection against the virus. Even if you're young and healthy, you should get a COVID-19 vaccine.

Yes, even if you get vaccinated, you're required to wear a mask in public indoor settings. Find more information on our Masks and Face Coverings FAQ page. We also recommend you wash your hands often, stay six feet apart, and limit gatherings.

The COVID-19 vaccines work well, but they are not 100% effective. Some people may get COVID-19 even if they've been vaccinated. With the rise of more transmissible variants, it's important that all people take precautions such as wearing masks to reduce transmission of the virus.

Some people who are moderately or severely immunocompromised should get four doses of COVID-19 vaccine.

Being immunocompromised means having a weakened immune system. This puts you in a high-risk group more likely than people with normal immune systems to contract COVID-19 and get severely ill from COVID-19. It also means that your body may not absorb the COVID-19 vaccine fully, requiring an additional dose for maximum protection.

You qualify for four total doses of COVID-19 vaccine if:

The CDC recommends that some people age 5 and older who are moderately or severely immune compromised and who got an mRNA vaccine as their primary series receive an additional (third) primary dose 28 days after their second dose. This is a total of three doses for the primary series. Five months after the primary series is completed, if you are at least age 12 you should get a booster dose for added protection.

Children ages 5-11 who are immune compromised should get an additional (third) primary dose of Pfizer vaccine, but do not qualify for a booster at this time. Children in this age range may not receive any vaccine other than Pfizer.

Immune compromised people who received Johnson & Johnson (Janssen) vaccine as their primary series should not receive an additional primary dose. They should follow the standard recommendation and receive a booster dose 2 months after their primary dose of Johnson & Johnson.

If you or your physician have any questions, please review the CDC guidelines for immunocompromised people or visit the DOH website. You may provide the link to this page or to the CDC's recommendations to your physician.

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How Does the COVID-19 Vaccine Work? - Washington State Department of Health