COVID-19 Vaccine FAQ

Having questions about COVID-19 vaccines is completely understandable. While medical and public health experts are still learning about COVID-19 and COVID-19 vaccines, there is a lot we do know. Check out the below answers to some of your most common questions. 

What COVID-19 vaccines are currently being used?

Three vaccines are currently approved to protect against COVID-19: the Moderna vaccine and the Pfizer/BioNTech vaccine (which were both approved in December, 2020) and the Janssen Biotech vaccine (which was approved in February 2021). The Moderna and Pfizer vaccines are mRNA vaccines and require two doses three weeks apart (Pfizer) or four weeks apart (Moderna) for full protection. The Janssen vaccine is an adenovirus viral vector vaccine and requires only one dose.

Are the vaccines safe?

Yes. No corners were cut in developing safe vaccines, despite the speed at which they were developed. The authorized vaccines 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 systems to ensure safety. Many of these systems have existed for many years and work well to ensure that the benefits of vaccination continue to outweigh the risks. 

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. The Janssen Biotech 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.

How many people were involved in the clinical trials?

In the Pfizer/BioNTech clinical trials, there were over 41,000 participants. In the Moderna trials, there were over 28,000 participants. In the Janssen Biotech trials, there were about 40,000 participants. Trials for both vaccines included diverse patient populations to closely match the demographics of the U.S. population and ensure representation from different age groups, races and ethnic backgrounds. In the Moderna trial, 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 Pfizer trial, about 30% of U.S. participants were from racial and ethnic minorities, and about 45% of U.S. participants were between 56 – 85 years of age. In the Janssen Biotech trials, 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.

How do mRNA 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 get rid of it.

How do viral vector vaccines work?

Viral vector vaccines work by using a different virus (in the 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 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.

Is the vaccine free?

Yes. No one, whether they are privately insured, on Medicaid or Medicare, or uninsured will have to pay to get the COVID-19 vaccine.

Who can receive the COVID-19 vaccine?

In time, everyone who wants a vaccine will be able to get one, but the limited supply of vaccines available at the moment are being prioritized first for those most at risk for contracting and experiencing severe outcomes from COVID-19. Colorado is currently vaccinating those in Phase 1A, Phase 1B.1 and Phase 1B.2, which includes health care workers, long-term care residents and employees, people aged 65 and over, first responders, pre-K-12 educators and childcare workers in licensed child care programs and some members of State government. The state health department will make public announcements once the state is ready to shift from one phase to the next and provide information to vaccine providers about how to get in touch with patients eligible to receive the vaccine. Visit for updates.

Where can I get the vaccine?

Because vaccine supplies are limited in Colorado, not everyone will have access to the vaccine at the same time. Most phase 1A recipients will receive the vaccine through their employer, local public health agency or through the federal government’s Pharmacy Partnership for Long-term Care (LTC) Program. Those in phase 1B who are 70+ can receive their vaccine through their health care provider; in some cases, hospitals will reach out to their patients. In other cases, patients of these hospitals may sign up to be contacted about scheduling a vaccination. Visit CDPHE's Where Can I Get Vaccinated page for more information. This page will be updated with additional information and vaccine locations as they become available. 

For more information on the COVID-19 vaccine, you can also call the CDPHE COVID-19 vaccine hotline, available Monday through Friday (9am - 10pm) and Saturday and Sunday (9am-5pm): 1-877-CO VAX CO (1-877-268-2926)

If I have allergies to food or medication can I get vaccinated?

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 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.

I'm pregnant. Can I get vaccinated?

Yes. People who are pregnant or breastfeeding may choose to get the vaccine if they are part of a recommended group (e.g. health care workers). 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 an mRNA COVID-19 vaccine.

I'm immune-compromised. Can I get vaccinated?

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.

Can my child get the vaccine?

COVID-19 vaccines have not yet been approved for use in people younger than 16 years old. Both the Moderna and Pfizer vaccines are currently being tested in children as young as 12 years old. You can still protect your child from COVID-19 by making sure the adults around them get a COVID-19 vaccine when they are able, and by continuing to follow public health measures like mask-wearing, hand-washing and physical distancing.

I've already had COVID-19. Should I get vaccinated?

Yes. People who have previously had COVID-19 infection can be vaccinated. Those currently infected should wait until their illness has resolved. Because reinfection with the coronavirus is uncommon in the 90 days following initial infection, people who have had recent infection can still get vaccinated but may also delay vaccination until the end of that 90-day period.

Why should I get the vaccine when it's my turn?

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.

I'm a person of color. Why should I get the COVID-19 vaccine?

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 long will vaccine protection last?

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.

What are the side effects of the vaccine?

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 or headache. These side effects are common and a sign that the vaccine is doing its job and mounting an immune response. Experiencing side effects does not mean you have COVID-19. Remember, the vaccine cannot give you COVID-19.

What information will I need to provide in order to be vaccinated?

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. 

Will I need to continue wearing a mask, washing my hands and practicing physical distancing?

Even after you get your COVID-19 vaccine, it is still important to continue wearing a mask around others outside of your household, washing your hands often and practicing physical distancing as vaccination efforts continue and we work to build community protection. Scientists are fairly confident that the vaccines likely prevent transmission, however until there is more research that indicates this one way or the other, it is important to continue practicing these tried and true disease prevention measures in public.

For additional information and answers to other common questions, visit CDPHE's COVID-19 Vaccine FAQ.