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. Below you can find answers to your questions. Have a question that's not covered here? Contact us.
COVID-19 Vaccine FAQs
How Do COVID-19 Vaccines Work?
Three vaccines are currently in use to protect against COVID-19 in the U.S. Three vaccines have been authorized for emergency use by the FDA: the Pfizer-BioNTech mRNA vaccine (brand name Corminaty®), the Moderna mRNA vaccine (brand name Spikevax®), and the Johnson & Johnson-Janssen Biotech viral vector vaccine. The Pfizer/BioNTech vaccine was given final approval and licensed by the FDA on August 23, 2021 for those 16 years of age and older. Pfizer is still under Emergency Use Authorization for those 5-15. The Moderna and Pfizer vaccines are messenger RNA (mRNA) vaccines and require two doses of the same vaccine three weeks apart (Pfizer) or four weeks apart (Moderna) for full protection. The J&J vaccine is an adenovirus viral vector vaccine and requires only one dose. Learn how the different vaccines work.
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 and causes it to begin making protective antibodies, just like it would if we encountered 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.
Viral vector vaccines work by using a different virus (in the J&J/Janssen COVID-19 vaccine, this virus is called an "adenovirus") as a vector to deliver important instructions in the form of a gene to our cells. In the COVID-19 vaccine, this gene instructs our cells to make the SARS-CoV-2 spike protein, which triggers production of antibodies and a resulting immune response. The vaccine cannot cause infection with either COVID-19 or the virus vector (adenovirus). Viral vector vaccines have been well-studied and have even been used to respond to recent Ebola outbreaks. Watch this video to learn more.
The mRNA vaccines include:
- mRNA – This mRNA is for the cell to produce the spike protein of SARS-CoV-2, the virus that causes COVID-19.
- Lipids – These are molecules that are not able to dissolve in water. They protect the mRNA, so that it does not break down before it gets into our cells.
- Salts and amines – The Pfizer vaccine contains four salts. One is table salt. The salts are used to keep the pH of the vaccine similar to that found in the body, so that the vaccine does not damage cells when it is administered. The Moderna vaccine also contains four chemicals to balance the pH. Two are in a class of organic compounds known as “amines” and two are acetic acid and its salt form, sodium acetate. Acetic acid is the main component of vinegar (other than water).
- Sugar – This ingredient is literally the same as what you put in your coffee or in a dessert. It is used in both of the vaccines to help keep the “bubbles of fat” from sticking to each other or to the sides of the vaccine vial.
These are the only ingredients in the mRNA vaccines. There are no egg proteins, blood products, fetal material, gluten, preservatives, microchips or any animal products (including gelatin).
The J&J vaccine includes:
- Adenovirus – this is the deactivated virus that teaches the immune system to recognize the spike protein of SARS-CoV-2, the virus that causes COVID-19.
- Stabilizers – Salts, alcohols, polysorbate 80, and hydrochloric acid.
- Amino acids – compounds made up of hydrogen, nitrogen, oxygen, and carbon, and help produce important proteins in the body.
These are the only ingredients in the viral vector vaccine. There are no egg proteins, blood products, fetal material, gluten, preservatives, microchips or any animal products (including gelatin).
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 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 immune response to COVID-19.
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 vaccine, there is no live infection. Only a part of the virus–the spike protein–is produced in either mRNA or adenovirus 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 purely 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 the COVID-19 pandemic and help restore health and economic security for our families and communities. Getting the COVID-19 vaccine will help protect yourself, your family and your community from COVID-19. Together, we can help end the pandemic; it's up to all of us.
Everyone ages 5 and older who wants a vaccine can and should receive one. (Note: The Pfizer COVID-19 vaccine is the only vaccine currently available to children ages 5 to 17.) Read on below for specific guidance for pregnant persons, immune-compromised people, people with allergies, and young children.
Some studies have shown that after getting vaccinated against COVID-19, the body's immune response protecting us against the virus may not be as strong over time, decreasing its ability to protect against infection. This lowered effectiveness is likely also due to the greater infectiousness of the Delta variant. Because of this, on November 29, the CDC recommended booster doses of Pfizer's, Moderna's and J&J's COVID-19 vaccine for all adults. Anyone 18 and over should get a booster shot 6 months after their initial PFizer or Moderna series or 2 months after their initial J&J vaccine. Find a COVID-19 vaccine provider here.
No. As of September 2, it is recommended that moderately to severely immune-compromised individuals who received an mRNA vaccine for their initial two doses of COVID-19 vaccine receive a third, additional primary dose of the same vaccine at least 28 days after their second dose. This additional dose is not the same as a booster dose because it is considered part of the initial vaccine series, whereas a booster is not. The CDC made this recommendation because these populations are especially vulnerable to COVID-19 and may not build the same level of immunity as those who are not immune-compromised. A third dose will help immune-compromised individuals mount a better immune response to COVID-19. The groups
- Immune-compromised individuals (recommended)
- People 50-64 years of age with medical conditions putting them at higher risk for severe COVID-19 disease (recommended)
The CDC, in its recommendations approving the booster shots for Moderna and J&J, also announced that anyone who was eligible for a booster could get a different booster vaccine than their original doses. All of the vaccines are safe and effective and mix and match is not required. There is some early data that there is an elevated immune response to a different mRNA vaccine, but results are not conclusive and more data is needed.
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. Those currently infected should wait until their illness has resolved to get the vaccine. Because reinfection with the coronavirus is uncommon in the 90 days following initial infection, people who have had recent infection can still get vaccinated. They may choose to delay vaccination until the end of that 90-day period but are not required to do so. It is unclear how long natural immunity from COVID-19 disease lasts, or if it will protect from new variants. Getting vaccinated if you've already had COVID-19 adds an extra layer of protection against reinfection and severe illness.
People with severe allergies to a COVID-19 vaccine ingredient, a previous dose of COVID-19 vaccine, or to polysorbate should not get the COVID-19 vaccines. 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. People with severe allergies to anything else (medications, foods, bees, etc.) are allowed to get the COVID-19 vaccine but should wait at the location the vaccine was given for 30 minutes, instead of the 15 minutes that the general population are recommended to wait.
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 15 times more likely to die and 22 times 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.
People who take drugs to suppress their immune systems can be vaccinated so long as they do not have another condition for which vaccination is not advised. A conversation with a healthcare provider may be useful in answering patient-specific questions. As of September 2, it is recommended that moderately to severely immune-compromised individuals who received an mRNA vaccine for their initial two doses of COVID-19 vaccine receive a third dose of the same vaccine at least 28 days after their second dose. The CDC made this recommendation because this population is especially vulnerable to COVID-19 and may not build the same level of immunity as those who are not immune-compromised. A third dose will help immune-compromised individuals mount a better immune response to COVID-19. Those who received the Johnson & Johnson vaccine, are not recommended to receive a third dose of COVID-19 vaccine, however this recommendation could change.
Yes. Children between 5-11 and adolescents 12-17 can now receive the Pfizer COVID-19 vaccine. On November 2, 2021, the CDC Director gave final approval for an Emergency Use Authorization for the Pfizer vaccine for children aged 5-11. To find an appointment search the Colorado COVID-19 website. Children's Hospital Colorado is also offering pediatric clinics for the COVID-19 vaccine.
A COVID-19 vaccine has been approved for use in people as young as 5 years old, and is 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. The vaccine was reported as 90.7% effective in preventing symptomatic COVID-19 in children 5-11. The two-shot .3mL dose Pfizer vaccine regimen is available to children as young as 12, and a two-shot .1mL regimen is available to children between the ages of 5-11. If a child is turning 12 between their first and second dose, the American Association of Pediatrics recommend they get a second dose of the .1mL vaccine. The Moderna and Johnson & Johnson vaccines are available to those 18 and older. Pfizer and Moderna are also currently testing their vaccine in children ages 6 months-2 years old and 2 years old-5 years old, though it is not certain when that vaccine will be available to children in these age groups. You can still protect children under 5 from COVID-19 by making sure the older children and adults around them get a COVID-19 vaccine, and by continuing to follow public health measures like mask-wearing, hand-washing and physical distancing.
The pandemic has hit Black, Latinx, Native American and immigrant communities particularly hard due to systemic inequities fueled by historic racism. The vaccine will be critical for mitigating COVID-19’s continued impact on these communities. In Colorado, the Colorado Vaccine Equity Taskforce 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.
How Can I Get Vaccinated?
Coloradans ages 12 and older can receive a COVID-19 vaccine at numerous vaccination sites and clinics across Colorado. For information about where to get vaccinated in your area, visit the state health department's Where to Get Vaccinated webpage or call the vaccine hotline at 1-877-COVAXCO (1-877-268-2926). The hotline is available 24 hours a day, 7 days a week with answers available in multiple languages. For information about vaccine equity clinics and other pop-up clinics happening across the state, visit the Colorado Vaccine Equity Taskforce's Get Vaccinated webpage. Some vaccination sites and clinics require appointments, while others are available for walk-ups.
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 211colorado.org/covid-19 to learn more.
Some people will be required to get a COVID-19. This depends on a variety of factors, like where you work and/or where you go to school.
- Work Requirements
Beginning September 20, all Colorado state employees must either be fully vaccinated against COVID-19 or submit to twice-weekly testing. All Colorado staff who work in health care facilities licensed by the state health department are also be required to be vaccinated. Federal employees and contractors will also be required to be vaccinated by November 22, with no option to instead submit to regular testing. Lastly, anyone in the U.S. working for an employer with 100+ employees will be required to get vaccinated or submit to weekly testing.
- School Requirements
There is currently no 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.
Yes, the vaccine is free and no, you will not be required to show identification. No one, whether they are privately insured, on Medicaid or Medicare, or uninsured will have to pay to get the COVID-19 vaccine. You will not be asked to provide proof of insurance for the COVID-19 vaccine. Everyone, regardless of documentation status, can receive a vaccine. In Colorado, a vaccine provider should not ask to see your ID. You may need to provide basic information like name and phone number before getting your vaccine for contact purposes.
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. You do not need to provide proof of insurance to receive the vaccine.
Yes. In Colorado, the Healthy Families and Workplaces Act concerning paid leave rights allows employees to use supplemental public health emergency (PHE) leave to seek preventative care, including getting vaccinated, during a public health emergency.
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. The authorized vaccines for COVID-19 underwent the same rigorous approval process as other vaccines.
Vaccine manufacturers are required to follow guidance issued by the Federal 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 authorizing it for use. The results of all COVID-19 vaccine clinical trials are reviewed by over 50 independent experts by the time the vaccine is authorized. The authorized vaccines will be continuously monitored through many different safety systems to ensure the vaccines' 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 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.
In the J&J trials, there were about 40,000 participants. About 20% of trial participants were 65 years and older, about 45% were Hispanic or Latinx, about 17% were Black or African American, about 8% were American Indian or Alaska Native, and about 40% had at least one medical condition like obesity or high blood pressure.
In rare cases. The J&J vaccine was linked to a rare kind of blood clot in the weeks following vaccination. Distribution of the J&J vaccine was temporarily paused to investigate these reports. On April 23, the Advisory Committee on Immunization Practices (ACIP) of the CDC voted to lift the pause on the use of the Johnson & Johnson COVID-19 vaccine after careful review of safety data. Out of the nearly 8 million J&J shots that have been given so far, CDC and FDA identified just 15 cases of these rare blood clots. The risk to your health if you get COVID-19 is serious and the benefits of the J&J vaccine far outweigh the risk of a rare side effect like this. The pause and thorough review of the vaccine's safety and efficacy proves that vaccine safety monitoring systems are working, and that safety is a top priority. Experts will continue to monitor the situation to ensure the benefits of the vaccine continue to outweigh the risks. There is no concern about this adverse event in people who have received the Moderna or Pfizer 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 (about 140 out of 1 million doses of vaccine given) have experienced cases of mild heart inflammation, myocarditis and pericarditis, after getting an mRNA COVID-19 vaccine (Pfizer or Moderna). 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. While heart issues can seem scary, myocarditis and pericarditis can be mild and treatable. The CDC has been studying these cases closely and based on the latest evidence, determined that heart inflammation appears to be an incredibly rare side effect of mRNA COVID-19 vaccines (whereas the risk of myocarditis from COVID-19 infection is much higher) and concluded that the benefits of COVID-19 vaccination outweigh the risks. The FDA is continuing to study this rare side effect from the Moderna vaccine before approving their EUA request for adolescents 12-17. 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.
You may have heard that a small number of people (100 as of July 13) have reported developing Guillain-Barré syndrome (GBS) following vaccination with the Johnson & Johnson vaccine, out of 12.5 million doses administered in the U.S. Although the available evidence suggests some association between the J&J vaccine and GBS, it is not enough to establish a causal link. The FDA has reviewed the cases and determined that the known benefits of J&J vaccine continue to outweigh the known and potential risks. The FDA has issued a revised Johnson & Johnson (Janssen) COVID-19 Vaccine EUA Fact Sheet to include information about GBS and notes that vaccine recipients should seek medical attention right away if they develop any GBS symptoms after receiving the J&J COVID-19 Vaccine. Every year in the U.S. an estimated 3,000 - 6,000 people develop GBS and most recover fully. The FDA will continue to monitor reports of GBS following vaccination.
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. The Pfizer COVID-19 vaccine is also safe and effective for teens. And all of the COVID-19 vaccines are strongly recommended by the CDC for pregnant people. Pregnant people who become infected with COVID-19 are 15 times more likely to die and 22 times 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.
Are the Vaccines Effective?
The available vaccines are very effective. In clinical trials, both the Moderna and Pfizer vaccines demonstrated over 94% efficacy with two doses in adults, and the Pfizer showed 90% efficacy in children 5-11 and 12-17. The J&J vaccine demonstrated 85% efficacy at preventing severe cases of COVID-19 and 66% efficacy at preventing moderate and severe disease. All of the 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 continue practicing other disease-prevention measures like wearing a mask in public, washing your hands and maintaining distance from those outside your household until enough of the community is vaccinated to offer community immunity.
COVID-19 vaccines are incredibly effective, but they aren’t 100%. We know from clinical trials that Moderna and Pfizer are 95% effective, which is very high, but means that some people (about 4-5%) could get COVID-19 even if they are vaccinated. As of October 1, there have been 3,519 breakthrough cases reported out of 3.2 million fully vaccinated Coloradans, which is a rate of about 0.001%. While this number may be underreported, it still signals a very high vaccine efficacy. If you do get COVID-19 after being vaccinated, your risk of getting severely ill, being hospitalized or dying is very low. This is how we know the vaccines are working. In Colorado, if you are vaccinated, you are 3.3 times less likely to get COVID-19, 4.9 times less likely to be hospitalized for COVID-19, and 5.9 times less likely to die from COVID-19. All COVID-19 vaccines are nearly 100% effective at preventing severe illness leading to hospitalization and death. And since the Delta variant, which is the dominant strain currently causing COVID-19 infections, spreads more easily and quickly among unvaccinated people, there’s a lot more virus circulating, which is also contributing to breakthrough cases.
All three vaccines currently available for public use are shown to be highly protective and effective (nearly 100% in fact) at preventing hospitalization and death due to COVID-19. All the vaccines are effective tools for helping end the pandemic. The best vaccine is the one most readily available to you.
It is not currently known how long protection from the COVID-19 vaccine will last. However, COVID-19 has caused serious illness and death for many people and getting the COVID-19 vaccine is far safer than getting COVID-19 and spreading it to others. Because scientists are still researching the vaccine’s protective longevity, it is important to continue disease prevention habits like wearing a mask and physically distancing from others. Health officials have announced the approval of booster doses of mRNA vaccines to recharge the immune system and offer bolstered protection; these booster doses are available to those 65+, and those 18-64 working or living in high-risk environments. For the full public, these boosters would be recommended for individuals who received both doses of either Pfizer or Moderna's COVID-19 vaccine, 8 months after their second dose. A third, additional dose of COVID-19 vaccine is currently recommended for immune-compromised individuals.
Yes. You may have heard that there are variants of the COVID-19 virus that are circulating. According to the CDC, the current vaccines available in the U.S. help protect against these variants, including one that you may be hearing a lot about called Delta. The Delta variant was first found in the U.S. in March 2021 and has since been deemed a "variant of concern" because it spreads much more easily and quickly than other variants and may cause more severe disease. As of October 1, the Delta variant is causing 99% of the COVID-19 cases in the U.S. and cases and hospitalization rates are again rising, especially in areas with low vaccination rates. Health officials have claimed that this is now a "pandemic of the un-vaccinated" as those who are unvaccinated account for about 99% of deaths and 97% of hospitalizations due to COVID-19. As a precaution to help stop the spread of the Delta variant, state and local officials may choose to require masks to help protect those who are not fully vaccinated.
In August, CDC updated its guidance on mask-wearing: they are now recommending that everyone, fully vaccinated or not, wear a mask indoors in public if you are in an area of substantial or high transmission. Everyone is required to wear masks on planes, buses, trains and other public transit. People who are not fully vaccinated should continue to wear masks indoors everywhere and around others outside of their household. For more information on Colorado's mask requirements, visit www.covid19.colorado.gov/mask-guidance.
People who are vaccinated but have weakened immune systems should consider continuing mask-wearing and other disease prevention measures at all times, and should consult their doctor to discuss these protections. Even with new evidence about the COVID-19 vaccines' effectiveness, continuing to wear a mask even when and where one is not required is ultimately an individual choice and everyone should continue to do what is most comfortable for themselves and their families based on their risk and preference.