COVID-19 Vaccine - Facts and FAQs
Safety is a top priority in delivering a COVID-19 vaccine. Once a company develops a vaccine, it must go through a complex scientific testing process before it can be submitted to the Food and Drug Administration (FDA). The FDA independently reviews the information from these tests to make sure the vaccine is safe and works well, and then decides whether the vaccine can be made available to the public through emergency use authorization.
After a vaccine is authorized for use, multiple safety monitoring systems are in place to watch for possible adverse events. If an unexpected serious adverse event is detected, experts work as quickly as possible to determine whether it is a true safety concern.
For Additional Information
Several vaccines have been authorized by the U.S. Food and Drug Administration (FDA). All COVID-19 vaccines have been proven to be highly effective at preventing serious illness, hospitalization and death from COVID-19. The best vaccine is the one you can get soonest and is available to you. However, if you have previously had a severe allergic reaction to any ingredients in a vaccine or have any concerns about your possible contraindications, be sure to check with your doctor for more information about your options. Get the facts about each vaccine using the links in the chart below.
|Type||Doses Needed||Approved for Ages||When You Receive Full Protection||Fact Sheet|
|Pfizer||mRNA||2||12+||Two weeks after receiving the second dose||Pfizer-BioNTech Vaccine Fact Sheet (Español)|
|Moderna||mRNA||2||18+||Two weeks after receiving the second dose||Moderna Vaccine Fact Sheet (Español)|
|Johnson and Johnson||Viral Vector||1||18+||Two weeks after vaccination||Johnson and Johnson (Janssen Biotech) Vaccine FDA Fact Sheet
Prevent Serious Illness
COVID-19 vaccination will help protect you from getting COVID-19 and has been proven to prevent serious illness, hospitalization and death from the virus.
You may have some side effects after vaccination, which are normal signs that your body is building protection. These may affect your ability to do daily activities, but they should go away in a few days. Some people have no side effects.
According to clinical trial data reviewed by the FDA, the most commonly reported side effects, which typically last several days, are:
- Pain at the injection site
- Muscle pain
- Joint pain
Of note, for those who received Pfizer or Moderna vaccines, more people experienced these side effects after the second dose than after the first dose, so it is important for vaccination providers and recipients to expect that there may be some effects after either dose, but even moreso after the second dose.
If you receive Pfizer or Moderna for your first dose, you should get the second shot even if you have side effects after the first shot, unless a vaccination provider or your doctor tells you not to get it.
After you receive your first dose of vaccine, you will receive a paper vaccination record that shows which vaccine you received and when. Keep this card in a safe place. Bring this card with you if your vaccine requires a second dose (I.e., Pfizer or Moderna) so that your provider can document your full vaccination.
Find out if COVID-19 vaccination is recommended for you right now on our eligibility page.
Find a vaccination site near you on our vaccine locations map.
Find more vaccine topics in our FAQs.
Find more information from CDC on what to expect at your vaccine appointment
Pfizer or Moderna
If you received the Pfizer or Moderna vaccine, you’ll need to return for a second dose vaccination 21 or 28 days later, respectively. Getting the second dose is important to ensuring you receive the full protective benefits of the vaccine. COVID-19 vaccines are not interchangeable. That means you will need to get the same manufacturer for the second dose as you received for your first dose. If you go to a different provider than your first dose, be sure to check ahead to ensure they offer the manufacturer you need.
According to ACIP/CDC recommendations, you can get your second dose as late as 42 days after the first dose with no impact on the protective benefit you’ll receive. If you get it later than 42 days after the first dose, it is likely to still be effective, although there has not been enough time to study that yet. CDC does not recommend starting over with vaccination. Remember: Getting the second dose is important to getting the full protective benefits of the vaccine, so schedule it as soon as you are able.
Johnson and Johnson (Janssen)
The Johnson and Johnson vaccine requires only a single dose for full vaccination. You will not need to return for a second appointment.
It takes about two weeks after being fully vaccinated to achieve full protective benefits from any COVID-19 vaccine.
After Full Vaccination
We’re still learning how vaccines will affect the spread of COVID-19. After you’ve been fully vaccinated against COVID-19, you no longer need to wear a mask or physically distance in any setting (except where required by federal, state, local, tribal, or territorial laws, rules, and regulations, including local business and workplace guidance).
If you’ve been fully vaccinated, meaning it’s been two weeks since your second dose in a 2-dose series or 2 weeks after a single-dose vaccine, there are some things you can start doing, according to CDC guidance:
- You can gather outdoors and indoors without wearing a mask, except where required by federal, state, local, tribal, or territorial laws, rules and regulations, including local business and workplace guidance.
- You can travel domestically without testing before or after travel, and without self-quarantining after travel.
- If you’ve been around someone who has COVID-19, you do not need to stay away from others or get tested unless you have symptoms.
- However, if you live in a group setting (like a correctional or detention facility or group home) and are around someone who has COVID-19, you should still stay away from others for 14 days and get tested, even if you don’t have symptoms.
Frequently Asked Questions
No, COVID-19 vaccines do not change or interact with your DNA in any way. There are currently two types of COVID-19 vaccines that have been authorized and recommended for use in the United States: messenger RNA (mRNA) vaccines (Pfizer and Moderna) and a viral vector vaccine (Johnson and Johnson). Both mRNA and viral vector COVID-19 vaccines deliver instructions (genetic material) to our cells to start building protection against the virus that causes COVID-19. However, the material never enters the nucleus of the cell, which is where our DNA is kept. This means the genetic material in the vaccines cannot affect or interact with our DNA in any way. All COVID-19 vaccines work with the body’s natural defenses to safely develop immunity to disease.
Learn more about how mRNA COVID-19 vaccines work.
Learn more about how viral vector vaccines work.
CDC’s v-safe is a new smartphone-based, after-vaccination health checker for people who receive COVID-19 vaccines. When you receive your vaccine, you should also receive a v-safe information sheet telling you how to enroll in v-safe. If you enroll, you will receive regular text messages directing you to surveys where you can report any problems or adverse reactions you have after receiving a COVID-19 vaccine.
Like all vaccines, COVID-19 vaccines must go through a rigorous and multi-step testing and approval process before they can be used. Throughout vaccine development and distribution, there are numerous safety measures. These include:
- The Federal Food and Drug Administration (FDA) authorizes and monitors all clinical trials.
- To get an Emergency Use Authorization, developers of a vaccine must provide a large amount of data on its safety and effectiveness to meet the rigorous standards set by the FDA
- Independent advisory committees provide oversight and monitor for safety during vaccine development and testing.
- Clinical trials for a vaccine continue after EUA is granted until enough data is available to grant full approval
After a vaccine is authorized for use, multiple safety monitoring systems are in place to watch for possible adverse events. If an unexpected serious adverse event is detected, experts work as quickly as possible to determine whether it is a true safety concern.
After a vaccine is authorized or approved for use, many vaccine safety monitoring systems watch for possible side effects. This continued monitoring can pick up on adverse events that may not have been seen in clinical trials and helps to ensure that the benefits continue to outweigh the risks for people who receive vaccines.
CDC is working to expand safety surveillance through new systems and additional information sources, as well as by scaling up existing safety monitoring systems specifically to evaluate COVID-19 vaccine safety in real time and make sure COVID-19 vaccines are as safe as possible.
Both the Pfizer and Moderna COVID-19 vaccines require two doses. The Pfizer vaccine requires two doses 21 days apart, while the Moderna vaccine requires two doses 28 days apart. COVID-19 vaccines are not interchangeable. The safety and efficacy of a mixed-product series (i.e., one dose of Pfizer, one dose of Moderna or vice-versa) have not been evaluated. Both doses of the series should be completed with the same product.
You should have received a vaccination card at your first dose appointment that included the name of the manufacturer of the vaccine you received (e.g., Pfizer or Moderna) and the timeframe needed to return for your second dose. Be sure to bring your COVID-19 vaccination record card to ensure appropriate product and vaccine dose interval at your second appointment. (Tip: Consider taking a picture or making a copy of this card so you have a back-up in case the card is lost.)
In exceptional situations in which the first-dose vaccine product cannot be determined or is no longer available, CDC guidance states any available mRNA COVID-19 vaccine (i.e, Pfizer or Moderna) may be administered at a minimum interval of 28 days between doses to complete the mRNA COVID-19 vaccination series. If two doses of different mRNA COVID-19 vaccine products are administered in these situations (or inadvertently), no additional doses of either product are recommended at this time (i.e. no third doses should be administered).
According to clinical trial data reviewed by the FDA, the most commonly reported side effects, which typically lasted several days, were pain at the injection site, tiredness, headache, muscle pain, chills, joint pain, and fever. Of note, more people experienced these side effects after the second dose than after the first dose, so it is important for vaccination providers and recipients to expect that there may be some side effects after either dose, but even more so after the second dose. Learn more.
Yes. If you are trying to become pregnant now or want to get pregnant in the future, you may receive a COVID-19 vaccine when one is available to you.
There is currently no evidence that COVID-19 vaccination causes any problems with pregnancy, including the development of the placenta.
In addition, there is no evidence that fertility problems are a side effect of any vaccine, including COVID-19 vaccines. Like all vaccines, scientists are studying COVID-19 vaccines carefully for side effects now and will continue to study them for many years.
There are no specific data on the safety of COVID-19 vaccines in pregnant women from clinical trials. If you are part of a group (e.g., healthcare personnel) who is recommended to receive a COVID-19 vaccine and are pregnant or breastfeeding, you may choose to be vaccinated. A discussion with your healthcare provider can help you make an informed decision. Read more on COVID-19 and pregnancy.
If you are immunocompromised, or are receiving immunosuppressant therapy, you may choose to be vaccinated, but may have a diminished immune response to the COVID-19 vaccine.
CDC recommends that the vaccine be administered to those with chronic health conditions if they have no contraindications.
If you have a history of severe allergic reaction (such as anaphylaxis or requiring epinephrine injection or hospitalization) to another vaccine or injectable medication, you can still get the vaccine but will need to be observed for 30 minutes following the vaccination.
NOTE: This DOES NOT include allergic reactions to oral medications, food, pet dander, pollen or other environmental allergens.
Individuals with history of severe or immediate reaction to mRNA vaccines (Pfizer and Moderna), components of mRNA vaccines including polyethylene glycol (PEG) or polysorbate should not be vaccinated unless working with their healthcare provider or allergy specialist.
Likewise, individuals with a history of severe of immediate reaction to the Johnson and Johnson vaccine, components of the Johnson and Johnson vaccine including polysorbate should not be vaccinated unless working with their healthcare provider or allergy specialist. Individuals with a contraindication to an mRNA vaccine can receive the Johnson and Johnson vaccine and vice-versa.
The only individuals who should not receive the vaccine are those who have a history of severe allergic reaction (such as anaphylaxis or requiring epinephrine injection or hospitalization) to this vaccine or any of its ingredients, including polyethylene glycol (PEG) for the mRNA vaccines (Moderna and Pfizer) and polysorbate for the Johnson and Johnson (Janssen) vaccine
Find ingredients in fact sheets for
After thorough review of safety and efficacy data from tens of thousands of participants in clinical trials, the Food and Drug Administration authorized the Pfizer-BioNTech vaccine for distribution to individuals ages 12 years and older in May 2021. The only individuals who should not receive the vaccine are those who have a history of severe allergic reaction (such as anaphylaxis or requiring epinephrine injection or hospitalization) to this vaccine or any of its ingredients, such as polyethylene glycol (PEG). More information about the Pfizer vaccine.
Moderna and Johnson & Johnson
Moderna and Johnson & Johnson’s vaccines are currently authorized for ages 18 and up.
All three companies have begun clinical trials for younger kids.
The American Academy of Pediatrics has advocated for the inclusion of adolescents and younger children in COVID-19 clinical trials so that this population can also benefit from a COVID-19 vaccine.
Currently, there are no commercially-available tests to determine whether vaccination has worked or not. Commercially-available serology, or antibody tests, do not tell the complete story of immune protection. According to CDC, a vaccinated person is very likely to get a negative result from an antibody test, even if the vaccine was successful and protective. The type and performance of antibody tests vary in how they detect different parts of the virus. Some antibody tests only search for a specific protein found in response to infection, not by the current vaccines. Additionally, there are parts of our immune protection that will not show up in a test, like how memory immune cells will respond when exposed to the virus.
For these reasons, the CDC does not recommend antibody testing after you’ve been vaccinated. If you do decide to get antibody tested after vaccination, CDC says additional doses of the same or different COVID-19 vaccines are not recommended. If antibody testing was done after the first dose of an mRNA vaccine, the vaccination series should be completed regardless of the antibody test result. While the potential need for booster vaccines is being studied, there are no current recommendations when or for which vaccines a booster is needed.
This will depend on what vaccine you receive. The Pfizer and Moderna COVID-19 vaccines will require two doses given 3 to 4 weeks, respectively, apart to provide maximum protection. The series of two doses must be completed with the same vaccine product.
The Johnson and Johnson vaccine only requires one dose for full vaccination.
After receiving your first shot, everyone will receive a paper immunization record that will be completed at the time of vaccination. It will include the vaccine you received, date and location, and date when your next shot is needed. In most cases, individuals will be reminded by the provider where they received their first dose when it’s time to schedule their second shot. Because different COVID-19 vaccine products will not be interchangeable, a vaccine recipient's second dose must be from the same manufacturer as their first dose.
COVID-19 vaccines will be administered by intramuscular (IM) injection, a shot in the arm.
The CDC recommends that those who have had COVID-19 get the vaccine. Due to the severe health risks associated with COVID-19 and the fact that reinfection with COVID-19 is possible, you should be vaccinated regardless of whether you already had COVID-19 infection. Research shows that individuals who are vaccinated after recovering from COVID-19 have an immune response 1000 times stronger after being vaccinated than those who are not vaccinated and that the vaccine provides some immunity against other COVID-19 strains that does not occur after natural infection. If you were treated for COVID-19 symptoms with monoclonal antibodies or convalescent plasma, you should wait 90 days before getting a COVID-19 vaccine. Talk to your doctor if you are unsure what treatments you received or if you have more questions about getting a COVID-19 vaccine.
You should wait to be vaccinated until your isolation period has ended and you are fully recovered (without symptoms)to avoid exposing healthcare personnel or other persons during your vaccination visit.
No. People with COVID-19 who have symptoms should wait to be vaccinated until they have recovered from their illness and have met the criteria for discontinuing isolation; those without symptoms should also wait until they meet the criteria before getting vaccinated. This guidance also applies to people who get COVID-19 before getting their second dose of vaccine.
No. None of the COVID-19 vaccines contain the live virus that causes COVID-19, so the vaccine cannot make you sick with COVID-19. You may have symptoms like a fever after you get a vaccine. This is normal and a sign that your immune system is learning how to recognize and fight the virus that causes COVID-19.
Yes, even if you get vaccinated, we recommend you continue with the other prevention measures you've been doing, such as washing your hands, wearing a mask, staying six feet apart, and limiting gatherings.
There will be no cost to get the COVID-19 vaccine, regardless of insurance status. If you do have insurance, you may be asked for it so that the provider can bill the insurer for its administrative fee. You will not be charged.
No, a vaccine will not end the pandemic by itself. A safe and effective vaccine against COVID-19 will be a major breakthrough in preventing COVID-19 infections but needs to be used in combination with other prevention measures until enough people have immunity (either from a vaccine or a past infection).
We will continue to update these FAQs and add additional information as it becomes available. More information also can be found on the CDC COVID-19 Vaccine page. Learn more about finding credible vaccine information.
A POD, or Point of Dispensing, is a temporary site in the community where vaccines or medicines can be quickly administered to people in large numbers. A POD allows us to vaccinate as many people as possible in a quick, safe and efficient manner.
Yes, CDC updated their guidance in May 2021 for coadministration of vaccinations with COVID-19 vaccines. COVID-19 vaccines and other vaccines may now be administered without regard to timing This includes simultaneous administration of COVID-19 vaccines and other vaccines on the same day, as well as coadministration within 14 days. Follow this link for best practices regarding coadministration of vaccines.
Even if you get COVID-19 after your first vaccine dose, you should complete the recommended vaccine series to get the maximum protection against future infections. We do not know how long protection from a natural infection lasts, so individuals should complete the full series.
Before getting the second dose at the recommended timeframe, you should ensure your isolation period has ended and you are fully recovered (without symptoms) to avoid exposing healthcare personnel or other persons during your vaccination visit.
Taking over-the-counter medications such as acetaminophen and ibuprofen before receiving a vaccine is not recommended.
These medications can be taken after vaccination, if needed, to help with any side effects like a sore arm, muscle aches or fever that may occur.
The CDC and other scientific partners are actively investigating the effectiveness of currently authorized vaccines against emerging variants. Current studies suggest that antibodies generated by vaccination with currently authorized vaccines recognize and provide protection against these variants.
Ongoing clinical trials are evaluating the duration of protection from the COVID-19 vaccines. At this time, the need for and timing of COVID-19 booster doses have not been established.
In most cases, if people who have been fully vaccinated against COVID-19 are exposed to someone with COVID-19, they do not have to quarantine if they meet all of the following criteria:
- it has been at least 2 weeks since their final dose, and
- they have had no symptoms since their COVID-19 exposure.
Exceptions to this guidance include:
- Inpatients/residents in healthcare settings (i.e., hospitals, hospice, skilled nursing facilities) and inmates in jail/prison must quarantine for the full 14 days.
- Public Health may determine that people who are a part of an outbreak due to a variant strain of the virus that causes COVID-19 should quarantine for the full 14 days regardless of vaccination status.
Please note: Even in the absence of quarantine, a person who has been exposed to COVID-19 should continue to monitor for symptoms for 14 days after their last exposure and wear a face mask.
Most vaccination sites have online appointment systems where you can check availability. Some vaccinators may offer scheduling assistance over the phone or take walk-ins. You can find providers offering vaccine on our locations page here.
To achieve maximum protective benefit as soon as possible, it is recommended you get your second dose of vaccine 21 days (Pfizer) to 28 days (Moderna) after your first dose. However, because of vaccine supply and demand for first dose appointments, we know this may not always be possible. According to ACIP/CDC recommendations, we know that you can get your second dose as late as 42 days after the first dose with no impact on the protective benefit you’ll receive. If you get it later than 42 days after the first dose, it is likely to still be effective, although there has not been enough time to study that yet. CDC does not recommend starting over with vaccination. Getting the second dose is important to getting the full protective benefits of the vaccine, so schedule it as soon as you are able.
Providers wanting to participate in the COVID-19 vaccination program are onboarded using the State’s electronic provider onboarding tool. Learn more about that process here Version OptionsCOVID-19 VaccineHeadline PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF PDF . During the enrollment process, AZDHS verifies each provider’s ability to receive, store, handle, and administer vaccine.
Johnson & Johnson
Yes, on April 23rd, the CDC Advisory Committee on Immunization Practices (ACIP) and FDA recommended that vaccination with the J&J/Janssen COVID-19 Vaccine resume among people 18 years and older. The fact sheet for recipients and caregivers was updated with information regarding an increased risk of thrombosis with thrombocytopenia syndrome (TTS) following vaccination with the J&J vaccine. TTS is a serious condition that involves blood clots with low platelets. Adult women less than 50 years old are at higher risk for this side effect, with women out of 1 million vaccine doses being affected. Existing safety monitoring systems allowed us to detect this very rare but serious side effect.
On April 13th, the Centers for Disease Control and Prevention and the Food and Drug Administration recommended a temporary pause on the use of the Johnson and Johnson vaccine.
At the time of the CDC advisory panel review on April 23rd, 15 cases of thrombosis with thrombocytopenia syndrome (TTS) were identified among nearly 8 million individuals vaccinated. Among vaccinated women 18-49 years old, the group identified at higher risk, the rate for TTS was 7 per 1 million.
In addition to reviewing all available date, experts considered the benefits and risks of getting the vaccine and determined that the risks of being hospitalized or dying from COVID was much greater than the risk of this side effect from the J&J vaccine. They also discussed the importance of educating providers on how to recognize and treat this rare side effect, which improves outcomes.
For three weeks after receiving the vaccine, you should watch for possible symptoms of a blood clot, such as:
- severe headache,
- new neurologic symptoms, like numbness or weakness
- severe abdominal (belly) pain,
- shortness of breath,
- leg swelling,
- tiny red spots on the skin (petechiae), or
- new or easy bruising
Get medical care right away if you have any of these symptoms. Report your recent vaccination and any medications you are taking when you present for medical care.
The same type of severe blood clots have not been reported among the more than 180 million people who received the Pfizer-BioNTech or Moderna vaccines.
Overall, the risk for this adverse event is rare. The data as of April 23, 2021, showed 15 cases of TTS after nearly 8 million doses of J&J vaccine were administered, or a rate of nearly 2 cases per 1 million doses. For women ages 18-50, the risk is 7 cases per 1 million doses given.
No, aside from the increased risk seen in women ages 18-50 years old there are no known medical conditions or factors that increase risk. The American Society of Hematology reports that “there is no information to date on any increased risk for TTS in and/or pre-existing risk factors for thrombosis or autoimmunity.” If you have questions or concerns, talk with your healthcare provider.
If you have questions or concerns, talk with your healthcare provider.
You can review the revised Fact Sheet for Healthcare Providers Administering J & J which has been revised to include a warning about the risk of thrombosis with thrombocytopenia syndrome (TTS).
For the latest guidance and recommendations for use of the vaccine, and how to assess and care for a patient that presents with thrombosis or thrombocytopenia, visit the CDC website.
CDC hosts weekly Clinician Outreach and Communication Activity (COCA) calls/webinars with the latest vaccine updates. Sign up information and past episodes can be found here.
Maricopa County Public Health also hosts webinars for providers every 2 weeks on Wednesdays at 11 a.m. Sign up here.
If you experience side effects after any vaccine, please report them to the FDA/CDC Vaccine Adverse Event Reporting System (VAERS). The VAERS toll-free number is 1-800-822-7967 or report online to https://vaers.hhs.gov/reportevent.html.
The only concern for patients on blood thinners is for prolonged bleeding after an intramuscular injection, this is why it is asked on some pre-screeners. If the individual has not had problems with prolonged bleeding previously they should not expect a problem with J&J or other IM injections.