COVID-19 Vaccines
It's completely normal to have questions about COVID-19 vaccines. While medical and public health experts are still learning about COVID-19, there is a lot we do know about the vaccines that prevent it. Find answers to your questions in the list of frequently asked questions (FAQ) below.
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COVID-19 Vaccine FAQs (Frequently Asked Questions)
How Do COVID-19 Vaccines Work?
The current COVID-19 vaccines used in the United States are updated formulas from Pfizer, Moderna, and Novavax.
The SARS-CoV-2 virus changes as it circulates, creating new variants. Current vaccines were formulated to target protection on the circulating variant. This is similar to how flu vaccines are formulated each year. Immunity from vaccination and infection wanes after a few months. This is why staying current with vaccination is important.
mRNA vaccines provide a set of instructions that teach our cells how to make a piece of a spike protein that triggers an immune response in our bodies. This causes our bodies to begin making protective antibodies, just like it would if we encountered the COVID-19 virus. These antibodies are then prepped and ready to fight off the virus if we are ever exposed to it, before it causes infection. mRNA vaccines cannot make you sick with COVID-19 because they do not use the live virus that causes COVID-19. mRNA vaccines do not change or alter your DNA. Once the vaccine is done triggering our cells to create the spike protein, our cells break down the mRNA and expel it. Watch this video to learn more.
The Novavax protein subunit vaccine teaches the body to fight the coronavirus by delivering copies of the virus’ spike protein (the spikes on the outer sphere of the virus) to the body. The immune system recognizes these proteins as dangerous and creates antibodies, which provide protection against future COVID infection. The proteins are grown in insect cells and purified. Like other vaccines, the Novavax vaccine cannot cause COVID infection. The Novavax vaccine was developed in a way that is similar to other widely used vaccines, such as the Human Papillomavirus vaccine and the hepatitis B vaccine.
The number of doses varies based on a person’s age and their immunocompromised status. For best protection, individuals should stay up to date with the CDC's vaccine recommendations.
People who get the COVID-19 vaccine may experience no side effects at all. Others may experience mild side effects, which may include pain, swelling or redness at the injection site, fatigue, low-grade fever, chills, or headache. These side effects are common and a sign that the vaccine is doing its job and your body is mounting a robust immune response against future infections. Experiencing these side effects does not mean you have COVID-19. Remember, the vaccine cannot give you COVID-19. If you are able, do not take pain or cold medication as this might affect your body's future immune response to a COVID-19 infection.
Additionally, the COVID-19 vaccine has been shown to be safe for the pediatric population 6 months of age and over. There were no serious safety concerns found for this age group in clinical trials. COVID-19 vaccines are also safe to give along with other essential routine vaccinations. It is also important to note that there is more data on COVID-19 vaccine safety than there is for most medications, supplements, and vitamins.
No. Viral shedding occurs when small, whole viral particles are secreted from an infected person. In the case of the COVID-19 virus, this shedding might occur in saliva or mucus. With the COVID-19 vaccines, there is no live infection. Only a part of the virus–the spike protein–is produced in mRNA and protein subunit vaccines, not a whole viral particle (and that viral part does not replicate in the body). It is impossible for any viral shedding to occur as a result of the vaccine.
Who Can Get a COVID-19 Vaccine?
COVID-19 vaccines are one of the best tools we have to fight COVID-19. Getting the COVID-19 vaccine will help protect yourself, your family and your community from COVID-19. Together, we can help stop the spread of COVID-19; it's up to all of us.
Everyone ages 6 months and older who wants a vaccine can and should receive one. Read on below for specific guidance for pregnant persons, immune-compromised people, people with allergies, and young children. You can also visit the CDC’s website for current recommendations.
Updated vaccines are available from Pfizer, Moderna, and Novavax. The vaccines have been formulated to closely match and protect against current circulating variants. The CDC recommends that everyone ages 6 months and up receive the new formula to protect against severe COVID-19 infection, regardless of previous COVID-19 vaccination history. However, you should wait three months to be vaccinated following a COVID-19 infection.
Older Adults are among those at highest risk for severe COVID-19 infection, hospitalization, and death. Immunity from vaccination decreases significantly after 4–6 months. Because COVID-19 circulates year-round, rather than seasonally like flu, it is important to ensure immunity year-round. To do this, the CDC recommends adults 65 years of age and older receive a second dose of the 2024-25 COVID-19 vaccine 6 months after the first dose.
Adults and children who are immunocompromised are also at greater risk for severe illness and death from COVID-19 infection. This group of individuals has different recommendations for COVID-19 vaccines. Immunocompromised people 6 months and older can get a second COVID-19 vaccine six months after receiving their first. Beyond the second dose, immunocompromised people may receive additional doses of 2024-25 COVID-19 vaccines based on shared clinical decision-making with a medical provider after at least two months.
Regardless of immunocompromised status, everyone should ensure they are up to date with COVID-19 vaccines.
For most individuals, it is more important to get the vaccine that is most readily available than to be concerned with the vaccine brand. “Mixing and matching” is okay for those age five and older. Children six months to four years of age need the same vaccine brand for all doses.
You can get both the flu vaccine and a COVID-19 vaccine at the same time. Experts recommend that the vaccines be given in two separate locations–either one inch apart in the same arm or one in each arm.
Yes. People who have previously had COVID-19 infection can and should be vaccinated. Immunity, whether through infection or vaccination, wanes over time. Those currently infected should wait until their illness has resolved to get the vaccine, and may consider delaying vaccination for three months; talk to your doctor to see when to get vaccinated based on your health history. Staying current with COVID-19 vaccines is the safest way to stay protected from severe illness, hospitalization, or death.
Severe allergic reactions to vaccines are rare, but can happen. This can result is difficulty breathing, swelling of the tongue or throat, or a drop in blood pressure. If you experienced a severe allergic reaction to a previous COVID-19 vaccine, you should not receive another dose of that same type of vaccine. If you experienced a non-severe reaction to a previous vaccine, you can receive the same vaccine again. These individuals and those with severe allergies to anything else (medications, food, bees, etc.) should stay at the vaccine clinic for observation for 30 minutes after getting vaccinated, rather than the 15 minutes recommended for the general population. People who have had a severe allergic reaction to other vaccines in the past should consult their health care provider or an immunologist before receiving the vaccine. The Novavax protein subunit vaccine is another option for people who are allergic to one of the components of mRNA vaccines.
The CDC has published information that shows over 2 million doses of the Pfizer COVID-19 vaccine, only 21 individuals had an allergic reaction. Most of those reactions occurred in the initial 15 minutes after the vaccine was administered.
Yes. People who are pregnant or breastfeeding are strongly recommended to get vaccinated for COVID-19. According to the CDC, pregnant people who become infected with COVID-19 are more likely to have pre-term births than pregnant people not infected. COVID-19 vaccines are safe for pregnant people and can drastically reduce the risk of adverse pregnancy and neonatal outcomes. Pregnant and breastfeeding persons can consult with their health care provider before being vaccinated but aren’t required to. People who are trying to get pregnant do not need to avoid pregnancy after getting a COVID-19 vaccine.
Yes. Everyone six months of age and older should be vaccinated against COVID-19. Children as young as six months of age can get Pfizer or Moderna vaccines. The Novavax vaccine is available to anyone 12 and older.
COVID-19 vaccines are approved for use in people as young as 6 months old, and are recommended by the FDA, CDC, and the American Association of Pediatrics to prevent COVID-19 and the severe condition Multi-Inflammatory Syndrome in Children (MIS-C). Even if a child has had COVID-19, it is unclear how long natural immunity will last, and vaccination is the strongest precaution against reinfection, severe illness and death. We cannot predict the severity of infection in children, and it is not safe to say that children don’t experience severe illness with COVID-19 infection - in fact, 50% of children that have been hospitalized from COVID-19 had no underlying conditions! Moreover, while children are significantly less likely to die from COVID-19 than other age groups, recent studies show that COVID-19 is a leading cause of death in children.
The pandemic has hit Black, Latinx, Native American and immigrant communities particularly hard due to systemic inequities fueled by historic racism. Vaccines are critical for mitigating COVID-19’s continued impact on these communities. During the Public Health Emergency, the Colorado Vaccine Equity Taskforce (CVET) was formed to ensure that all groups – regardless of race, ethnicity, ability and other factors – have all the facts to make informed decisions about the safety of vaccines for their families, and to hold leaders accountable for ensuring access to these vaccines for all.
While the CVET's work has ended, Immunize Colorado remains committed to overcoming the disproportionate impact vaccine-preventable diseases have on marginalized people. We do this by supporting vaccine clinics for un- and underinsured Coloradans. We also contract with trusted messengers who organize clinics within the Latino, BIPOC, refugee, LGBTQ+, older adult, disability, and faith communities.
How Can I Get Vaccinated?
Anyone 6 months of age and older can receive a COVID-19 vaccine at numerous locations across Colorado. For information about where to get vaccinated in your area, visit bit.ly/FindCOVaxProvider where you can search for a vaccine provider based on your location and insurance status. Some vaccination sites and clinics require appointments, while others are available for walk-ins.
Don’t let transportation challenges stop you (or your family or friends) from getting vaccinated. Mile High United Way is providing access to free rides to vaccination sites across Colorado, Monday - Friday, 8am - 5pm, through their Ride United Program. Dial 2-1-1 or visit 211 Colorado to learn more.
Some people will be required to get a COVID-19 vaccine. This depends on a variety of factors, like where you work and/or where you go to school.
- Work Requirements
While many employers have lifted COVID-19 vaccine mandates, some continue to require COVID-19 vaccination as a condition of employment. The Occupational Safety and Health Administration (OSHA) strongly encourages vaccination.
- School Requirements
There is currently not a vaccine requirement in place for COVID-19 vaccines for Colorado K-12 schools and students. However, some colleges and universities have implemented COVID-19 vaccine requirements for students, staff, and faculty. Please check with your college or university to understand their specific requirements.
On May 11, 2023 the Public Health Emergency (PHE) expired ending the federal government's coverage of the cost of COVID-19 vaccines. While COVID-19 vaccines are no longer funded through the federal government, insurance will fully cover their cost. Additionally, the CDC’s Vaccines for Children program will fully cover the cost of vaccination for un- and underinsured children ages 18 and younger. While the Bridge Access program, which covered the cost of COVID-19 vaccines for un- and underinsured adults ended in August of 2024, vaccine advocacy groups like Immunize Colorado are advocating for a federal Vaccines for Adults program. This model would cover all routinely recommended vaccines for un- and underinsured adults, just as the Vaccines for Children (VFC) program covers them for un- and underinsured children.
Your information won’t be used for anything other than vaccine distribution and follow-up information about the vaccine. Like other routine vaccinations, you will need to share some personal information with your vaccine provider when you get a COVID-19 vaccine. This may include your name, date of birth, and contact information. You do not need to be a U.S. citizen to get a COVID-19 vaccine, and you will not need to provide a government-issued ID to get the vaccine in Colorado. Your immunization records are confidential, personal medical information, and public health will never share them publicly.
Yes. Colorado law allows employees to use paid sick leave for preventive care, including vaccination.
Are the Vaccines Safe?
Yes. No corners were cut in developing safe vaccines, despite the speed at which they were developed. Scientists have been researching coronavirus vaccines for decades, and other mRNA vaccines have been in research and development since 1995. COVID-19 underwent the same rigorous approval process as other vaccines.
Vaccine manufacturers are required to follow guidance issued by the Food and Drug Administration (FDA) when developing any vaccine, including COVID-19 vaccines. Each is required to provide their clinical trial data to the FDA, which the FDA and other experts use to conduct a thorough review of the vaccine’s safety and efficacy before they are released for public use. The results of all COVID-19 vaccine clinical trials were reviewed by over 50 independent experts by the time the vaccines were authorized. The vaccines will be continuously monitored through many different safety systems to ensure safety. Many of these systems have existed for decades and work well to ensure that the benefits of vaccination continue to outweigh any risks.
No safety steps were passed over to make the COVID-19 vaccine available as quickly as it was. Phase I trials were either combined with or replaced by Phase II trials, which just involve different numbers of people in clinical tests. Manufacturers also made the vaccine 'at-risk,' meaning they would have lost money if the vaccine did not work, a step that is usually not taken except in extreme circumstances like the COVID-19 pandemic. Different groups also sped up their logistics planning to make sure the vaccine could be distributed to vulnerable groups as soon as an emergency use authorization was granted by the FDA.
Trials for all vaccines currently authorized and approved for use in the U.S. included people from all communities to closely match the demographics of the U.S. population and ensure representation from different age groups, races and ethnic backgrounds.
In the Pfizer/BioNTech clinical trials, there were over 44,000 participants over the age of 16. The trial for 12 - 15 year olds included 2,260 adolescents. The trial for 5 - 11 year olds included 2,268 children. About 30% of U.S. participants in the Pfizer trials were from racial and ethnic minorities, and about 45% of U.S. participants were between 56 – 85 years of age.
In the Moderna trials, there were over 28,000 participants. 37% of participants were from racial and ethnic minorities, 7,000 participants were people age 65 and older, and over 5,000 participants were younger people with chronic diseases like obesity, cardiac disease and diabetes.
The Novavax vaccine trials included about 30,000 participants. 20% of all participants were Hispanic or Latinx, 12% were Black or African American, 7% were American Indian or Alaska Native, and 5% were Asian American. 13% of participants were 65 or older.
The J&J (Janssen) vaccine is no longer available in the U.S.
The J&J vaccine was previously linked to a rare kind of blood clot experienced in the weeks following vaccination. Distribution of the J&J vaccine was temporarily paused to investigate these reports. After the pause was lifted by the Advisory Committee on Immunization Practices (ACIP), scientists continued to study the risk. The rate of this side effect was found to be approximately 1 case in 100,000 doses in the highest risk group (women between 30-49). Out of 14 million doses, only 54 total individuals have experienced these blood clots.
In 2021, ACIP voted unanimously to update their guidelines to recommend the Pfizer and Moderna vaccines over the J&J vaccine due to their greater effectiveness and the limited risk of blood clots from the J&J vaccine. On May 7, 2023, all remaining doses of the J&J vaccine expired and providers were directed to dispose of any remaining vaccine. The pause, thorough review of the vaccine's safety and efficacy, and the decision to discontinue use of the J&J vaccine, prove that vaccine safety monitoring systems are working, and that safety is a top priority. There is no concern about this adverse event in people who have received the Moderna, Pfizer, or Novavax vaccines. For additional information, please visit Vaccinate Your Family's website.
In rare cases. You may have heard that a small number of teens and young adults have experienced cases of mild heart inflammation, myocarditis and pericarditis, after getting an mRNA COVID-19 vaccine (Pfizer or Moderna). There have been about 9 reported cases for every 1 million people vaccinated. The cases were observed mostly in older teens and young adults, more often in males, more often after the second dose of vaccine, and within four days following vaccination. The FDA is continuing to study this rare side effect from mRNA vaccines in newly authorized populations. Data from the Novavax clinical trials show that out of nearly 30,000 participants there were six cases of myocarditis, primarily among males. The six individuals all recovered. The risk of developing myocarditis from COVID-19 infection is greater than from a COVID-19 vaccine. While heart issues can seem scary, myocarditis and pericarditis can be mild and treatable. People with or parents whose children have a history of myocarditis or pericarditis can choose to consult with their doctor before getting vaccinated. There is no known additional risk to teens who play sports or exercise regularly.
No. Scientists agree that the COVID-19 vaccines do not impact puberty or fertility in females or males, now or at any time later in life. Producing mRNA is a part of our cells' natural processes. The mRNA vaccines teach our cells to make a harmless piece of spike protein that looks like, but is not, the COVID-19 coronavirus. This is so that our body builds antibodies for COVID-19 and can fight off future COVID-19 infections. It’s biologically impossible for those antibodies to attack other kinds of proteins that would in turn affect eggs, sperm, or cells in the reproductive organs. And COVID-19 vaccines are strongly recommended by the CDC for pregnant people. Pregnant people who become infected with COVID-19 are more likely to have pre-term births than pregnant people not infected. COVID-19 vaccines are safe for pregnant people, and can drastically reduce the risk of adverse pregnancy and neonatal outcomes.
Over a billion doses of mRNA COVID-19 vaccines have been administered with no evidence that they alter DNA or otherwise cause harm or illness.
mRNA COVID-19 vaccines do contain trace amounts (nanograms) of DNA fragments. However, it is impossible for these to alter our DNA. For that to be true, the DNA fragments would have to enter our cells’ nucleus. One of our cells’ jobs is to keep foreign DNA out. To enter our cells, the fragments would need an access signal that they do not have. And to enter our DNA, they would need an enzyme which they also do not have. The fact is that the trace amounts of DNA fragments in COVID-19 vaccines are completely harmless. After the body produces an immune response, it gets rid of all the vaccine ingredients it no longer needs, including these fragments. It is helpful to consider that our cells are also faced with foreign DNA daily when we eat plants and animals. This process does not change our DNA, just like the COVID-19 vaccines do not change our DNA.
Vast amounts of scientific evidence show COVID-19 vaccines are safe and do not cause cancer. Increases in cancer rates among some age groups occurred prior to the start of the COVID-19 pandemic. This is why colon cancer screenings are now recommended to begin at age 45 instead of age 50. During the pandemic, many cancer diagnoses were delayed because people were avoiding doctors’ visits. This meant that many people received a cancer diagnosis when their cancer had progressed or was in a later stage. Some have erroneously made the claim that these late-stage diagnoses are “turbo cancers,” but there is no such thing. While there is no evidence linking COVID-19 vaccines to cancer, the technology used in COVID-19 mRNA vaccines initially began as an effort to develop cancer vaccines. These vaccines are now undergoing trials and offer exciting progress in efforts to combat cancer.
Are the Vaccines Effective?
COVID-19 vaccines were shown to be effective at preventing hospitalizations and death due to COVID-19. However, no vaccine is 100% effective, which is why it's important to pair vaccination with other disease-prevention measures, like hand-washing, coughing and sneezing into a tissue or your elbow, and masking when you are sick.
COVID-19 vaccines are incredibly effective, but they aren’t 100%. If you do get COVID-19 after being vaccinated, your risk of getting severely ill, being hospitalized, or dying is very low. All COVID-19 vaccines are very effective at preventing severe illness leading to hospitalization and death. However, immunity from both vaccination and infection wanes over time. It's important to stay current with COVID-19 vaccines to maintain the best possible defense against the SARS-CoV-2 virus.
All COVID-19 vaccines currently offered in the U.S. have been shown to be highly protective and effective at preventing hospitalization and death due to COVID-19. Getting vaccinated and staying current is one of the most effective ways to keep yourself protected and help stop the spread of COVID-19.
COVID-19 vaccine protection is thought to last about 6 months. As protection wanes and new variants of the virus arise, it is important to stay current with COVID-19 vaccination. Following the CDC’s guidance on COVID-19 vaccines is crucial to maintaining immunity and avoiding severe illness, hospitalization, and death. It is also important to continue disease prevention habits like wearing a mask and physically distancing from others when appropriate.
Viruses change constantly to create new variants. COVID-19 vaccines offer strong protection against severe illness, hospitalization, and death, but may not always prevent infection. This has been the case with the currently circulating Omicron sub-variants. The CDC recommends that everyone over 6 months of age get vaccinated for COVID-19. Getting vaccinated is still the best way to protect against the virus and keep from spreading it to others.
The CDC recommends that individuals who are at high risk for severe illness wear a well-fitted mask or respirator. Individuals who are in contact with those who are at high risk should also mask in indoor settings and additionally seek testing before coming into physical contact with those at high risk. While masking is no longer a requirement in many environments, it remains an effective way to stop the spread of COVID-19 and other respiratory viruses like flu and RSV. Individuals may choose to continue masking in indoor settings and in areas with higher rates of infection.
COVID-19 Vaccine Information in Multiple Languages*
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*from Children's Hospital Colorado
For additional information and answers to other common questions, visit CDPHE's COVID-19 Vaccine FAQ.