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 emergency 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 COVID-19 vaccines have been authorized by the U.S. Food and Drug Administration (FDA). COVID-19 vaccines are safe and effective at reducing your risk of severe illness or hospitalization from COVID-19. For more information on staying up to date with COVID-19 vaccines to maximize your protection, visit the CDC website.
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.
Visit the CDC resources below for the most up to date information about the available COVID-19 vaccine.
- CDC: Stay Up to Date with Your COVID-19 Vaccines
- CDC: COVID-19 Vaccines for Moderately or Severely Immunocompromised People
- CDC: COVID-19 Vaccines Fact Sheets
- FDA COVID-19 Vaccine News and Updates
The COVID-19 vaccines recommendations will be different depending on your age and health status. There are several options for the COVID-19 vaccines. Staying up to date on the COVID-19 vaccines will give you the most protective benefits.
Staying up to date means getting all recommended COVID-19 vaccines, including a booster shot when eligible. Visit the CDC website to see the most recent COVID-19 vaccines recommendation.
- Two Dose Series: Pfizer (ages 12+), pediatric Pfizer (ages 5-11), Moderna (ages 18+), pediatric Moderna (ages 6months-5 years), Novavax (ages 18+)
The Pfizer, Moderna and Novavax COVID-19 vaccine requires two doses for the primary series. If you received the Pfizer, Moderna or Novavax COVID-19 vaccines, visit the CDC website to see when you need to get your second dose.
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.
- Three Dose Series: pediatric Pfizer (ages 6 months-4 years)
The pediatric Pfizer vaccine for ages 6 months to 4 years requires three doses for the primary series. Visit the CDC website to see when your child will need his or her second and/or third doses.
- Single Dose: Johnson and Johnson (Janssen)
The Johnson and Johnson COVID-19 vaccine requires a single dose for the primary series.
Depending on your age, and health status, what vaccine you received for your primary series, and when you first got vaccinated, the CDC may also recommends additional COVID-19 booster dose(s) to further enhance or restore protection that might have waned over time after your primary series vaccination.
To learn more information about the COVID-19 vaccines dosing recommendations, visit:
- CDC: Stay Up to Date with Your COVID-19 Vaccines
- CDC: COVID-19 Vaccine Boosters
- CDC: COVID-19 Vaccines for Moderately or Severely Immunocompromised People
Frequently Asked Questions
There are two different vaccines available for children of different ages.
The Pfizer vaccine has been granted an emergency use authorization (EUA) for children ages 6 months through 11 years old. The dosage for kids ages 5-11 is one-third of the adolescent (12-17) and adult dose. The dosage of for children 6 months-4 years is one-tenth of the adolescent (12-17) and adult dose, and requires a three-dose primary series. If you are unsure which option a provider is offering, be sure to ask.
The Moderna vaccine has been granted an emergency use authorization (EUA) for children ages 6 months through 5 years old. The dosage for kids ages 6 months-5 years is one-fourth of the adult dose.
There are more steps before the vaccines can get full approval.
When vaccines are developed, different doses are studied in multiple age groups to maximize the beneficial effects and minimize side effects for each group. In other words, clinical trials test different dosages of vaccines to determine how much is needed to prepare the immune system so it can stop germs from making someone sick based on their immune system’s age and development.
Vaccines work differently in the body than medications, which is why vaccine doses are based on age and medication doses are sometimes based on weight. To read more on this, visit the CDC’s page on COVID-19 Recommendations for Children and Teens.
For a primary series of COVID-19 vaccines (not including boosters), the dose and number of doses needed to effectively protect a person vary by age and by vaccine.
Staying up to date on the COVID-19 vaccines will give your child the most protective benefits. Visit the CDC website for the most up to date information on the COVID-19 vaccines and booster recommendations.
Learn more about COVID-19 vaccines for children and teens on the CDC website.
Yes. Before recommending COVID-19 vaccination for children, scientists conducted clinical trials with thousands of children to make sure the COVID-19 vaccination was safe and effective.
Tens of millions of children and teens have received a first dose of COVID-19 vaccine and ongoing safety monitoring shows that COVID-19 vaccination continues to be safe for children and teens.
Reported side effects tend to be mild, temporary and like those experienced after routine vaccination. Serious reactions after COVID-19 vaccination in children are rare. When they are reported, serious reactions most frequently occur the day after vaccination.
Learn more about COVID-19 vaccines for children and teens on the CDC website.
Similar to adults, children may experience side effects such as fever, body aches, and chills in the first few days after getting their vaccine. These are all normal, safe signs that the body is responding to the vaccine and activating an immune response that will protect them if they are exposed to the real virus.
No. There is no evidence that any vaccines, including COVID-19 vaccines, can cause female or male fertility problems. There is no evidence that vaccine ingredients, including mRNA, or antibodies made following COVID-19 vaccination would cause any problems with becoming pregnant now or in the future. Similarly, there is no evidence that the COVID-19 vaccine affects puberty.
To read more on this topic, visit the CDC’s page on COVID-19 Vaccines for People Who Would Like to Have a Baby.
COVID-19 vaccine dosage is based on age on the day of vaccination, not on size or weight. Children receive a smaller, age-appropriate dose.
To read more on this topic, visit the CDC’s page on COVID-19 Recommendations for Children and Teens.
The COVID-19 vaccine can be given at the same time as other routine vaccines.
Many parents have concerns about how their child might react to getting vaccinated. But there are simple ways to help make it a positive, calm experience. Here are a few:
Yes. Getting a COVID-19 vaccine after you recover from COVID-19 infection provides added protection against COVID-19. People who already had COVID-19 and do not get vaccinated after their recovery are more likely to get COVID-19 again than those who get vaccinated after their recovery.
Learn more about the benefits of getting a COVID-19 vaccine on the CDC website.
For more frequently asked questions about COVID-19 vaccination for children and teens, visit the CDC's Frequently Asked Questions about COVID-19 Vaccination for Children and Teens.
Please see COVID-19 variant FAQs.
Booster Shots and Additional Third Doses
Depending on your age, and health status, what vaccine you received for your primary series, and when you first got vaccinated, the CDC may also recommend additional COVID-19 booster dose(s) to further enhance or restore protection that might have waned over time after your primary series vaccination. For more information, visit the CDC's website on who boosters are recommended for and when to administer them.
If eligible, you can be vaccinated at many of the same locations you received your primary series, including pharmacies, community health clinics, private providers, and other vaccination events. You can search for locations on our vaccine locator page.
It is recommended you bring your COVID-19 vaccine card to your booster vaccine appointment to help verify your eligibility and so that the booster dose can be recorded on your record.
COVID-19 vaccine boosters can further enhance or restore protection that might have waned over time after your COVID-19 primary series vaccination. Booster shots are critical in maintaining your protection against the COVID-19 virus.
People are protected best from severe COVID-19 illness when they stay up to date with their COVID-19 vaccines, which includes a booster for many people. Learn more about the COVID-19 vaccine boosters.
- What is the difference between people who need a booster dose and people who need an additional third dose?
A booster dose is given to increase protection against an infection when immunity has waned, or weakened, after initial vaccination. People whose immune systems are compromised moderately to severely require a third dose to mount their initial immune response.
CDC has additional recommendations for people who are moderately or severely immunocompromised, which includes pregnant people. Based on your age and which vaccine you got for your primary series, visit the CDC website for the most up to date COVID-19 booster recommendation.
Everyone eligible, including immunocompromised people should get a booster shot. If you are eligible for an additional primary shot, you should get this dose first before you get a booster shot.
You should talk to your healthcare provider about your medical condition, and whether getting additional dose(s) of the COVID-19 vaccine is appropriate for you.
If you are recommended for a third dose based on your compromised immune status, check with your healthcare provider about vaccination options that may be available to you. You can be vaccinated anywhere that offers the same vaccine as your first and second doses. Bring your vaccination card with you so that they can document your additional dose.
There is no charge for a booster dose or an additional dose of vaccine. If you have insurance, please bring your card with you to your appointment. You will not be charged, but the vaccine provider may bill your insurer a fee for administering the vaccine.
Talk to your healthcare provider about your health status, and whether getting additional dose(s) is appropriate for you.
Visit the CDC website to see the most up to date information for people who are moderately or severely immunocompromised and have received a Johnson & Johnson/Janssen vaccine.
Yes. COVID-19 vaccination is recommended for people who are trying to get pregnant now or might become pregnant in the future, as well as their partners. People who are trying to get pregnant now or might become pregnant in the future should stay up to date with their COVID-19 vaccines, including getting a COVID-19 booster shot when it’s time to get one.
To learn more about COVID-19 vaccines for people who would like to have a baby, visit the CDC website.
All pregnant people or people who are thinking about becoming pregnant and those who are breastfeeding/chestfeeding are strongly encouraged to get vaccinated as soon as possible to protect themselves from COVID-19. Pregnant individuals are at increased risk of severe illness and pregnancy complications related to COVID-19 infection.
A recent CDC study of current data from the v-safe pregnancy registry assessed vaccination early in pregnancy and did not find an increased risk of miscarriage among nearly 2,500 pregnant women who received an mRNA COVID-19 vaccine before 20 weeks of pregnancy. Miscarriage typically occurs in about 11-16% of pregnancies, and this study found miscarriage rates after receiving a COVID-19 vaccine were around 13%, similar to the expected rate of miscarriage in the general population.
Learn more on this topic on the CDC website.
According to the CDC, no evidence currently shows that any vaccines, including COVID-19 vaccines, cause fertility problems (problems trying to get pregnant) in women or men. One study of 45 healthy men who received an mRNA COVID-19 vaccine looked at sperm characteristics, like quantity and movement, before and after vaccination. Researchers found no significant changes in these sperm characteristics after vaccination. Like with all vaccines, scientists are studying COVID-19 vaccines carefully for side effects and will report findings as they become available.
Additionally, there is increasing evidence that COVID-19 disease adversely effects the male testes and ongoing research is underway to confirm these effects.
People who are moderately to severely immunocompromised make up about 3% of the adult population and are especially vulnerable to COVID-19 because they are more at risk of serious, prolonged illness. The FDA-authorized COVID-19 vaccines are not live vaccines and can be safely administered to immunocompromised people. Close contacts, in particular household members, of immunocompromised people are strongly encouraged to be vaccinated against COVID-19.
Visit the CDC website for the most up to date COVID-19 vaccine recommendation for people who are moderately or severely immunocompromised.
If you have any of these medical conditions, you are more likely to get very sick with COVID-19. The CDC recommends staying up to date with COVID-19 vaccines and following preventive measures for COVID-19. This is especially important if you are older or have severe health conditions or more than one health condition.
If you have concerns related to allergic reactions to the COVID-19 vaccine, visit the CDC’s website for the most up to date information related to COVID-19 Vaccines for People with Allergies.
If you have allergies not related to vaccines or injectable medications-such as food, pet, venom, environmental, or latex allergies, the CDC recommends that you stay up to date on the COVID-19 vaccinations. People with a history of allergies to oral medications or a family history of severe allergic reactions may also get vaccinated.
If you are due for a screening mammogram and have been recently vaccinated for COVID-19, ask your doctor how long you should wait after vaccination to get your mammogram. People who have received a COVID-19 vaccine can have swelling in the lymph nodes (lymphadenopathy) in the underarm near where they got the shot. This swelling is a normal sign that your body is building protection against COVID-19. However, it is possible that this swelling could cause a false reading on a mammogram. Some experts recommend getting your mammogram before being vaccinated or waiting four to six weeks after getting your vaccine.
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:
Federal health officials are actively investigating and monitoring very rare occurrences of heart inflammation (myocarditis and pericarditis) after vaccination with mRNA vaccines (Pfizer and Moderna).
The risk of heart inflammation is small. The CDC recommends that recently vaccinated people seek medical attention if they develop any chest pain, shortness of breath, or have feelings of a fast-beating heart, particularly in the first week after vaccination.
CDC continues to recommend that everyone eligible should get vaccinated for COVID-19. The known risks of COVID-19 illness and its related, possibly severe complications, such as long-term health problems, hospitalization, and even death, far outweigh the potential risks of having a rare adverse reaction to vaccination, including the possible risk of myocarditis or pericarditis.
To see the most up to date information about myocarditis and pericarditis after mRNA COVID-19 vaccination, visit:
Guillain Barré syndrome (a neurological disorder in which the body’s immune system damages
nerve cells, causing muscle weakness and sometimes paralysis) has occurred in some people who have received the Janssen COVID-19 Vaccine.
In most of these people, symptoms began within 42 days following receipt of the Janssen COVID-19 Vaccine. The chance of having this occur is very low. You should seek medical attention right away if you develop any of the following symptoms after receiving the Janssen COVID-19 Vaccine:
Although rare, due the risk of adverse events, the CDC states in most situations, Pfizer-BioNTech or Moderna COVID-19 vaccines are preferred over the J&J/Janssen COVID-19 vaccine for primary and booster vaccination. You can read more on this on the CDC website.
No, COVID-19 vaccines do not change or interact with your DNA in any way. There are currently three types of COVID-19 vaccines that have been authorized and recommended for use in the United States: messenger RNA (mRNA) vaccines (Pfizer and Moderna), a viral vector vaccine (Johnson and Johnson), and a protein subunit vaccine (Novavax). The mRNA, viral vector, and protein subunit 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.
Learn more about how protein subunit vaccines work.
The mRNA vaccine technology in COVID-19 vaccines (Pfizer and Moderna) has been studied for over a decade, including in the development of vaccines for Zika, rabies and influenza. In addition, cancer research has used mRNA to trigger the immune system to target specific cancer cells.
mRNA COVID-19 vaccines are not live virus vaccines and do not interfere with human DNA. Once the injected mRNA enters a human cell, it breaks down quickly and only stays in the body for a couple of days. Decades of studying mRNA have shown no long-term side-effects.
Scientists began creating viral vectors in the 1970s, and they have been studied for other uses in addition to vaccines. Some vaccines recently used for Ebola outbreaks have used viral vector technology, and studies have focused on viral vector vaccines against other infectious diseases such as Zika, influenza and HIV.
Long-term side effects following any vaccination, including COVID-19, are extremely rare. In the past, vaccine monitoring has shown that if side effects are going to happen, they tend to happen within weeks of receiving a vaccine dose. For this reason, the FDA required each of the authorized COVID-19 vaccines to be studied for at least eight weeks after the final dose. Millions of people have received COVID-19 vaccines, and no long-term side effects have been detected. The long-term effects of COVID-19, commonly known as long-COVID, are well documented and in some cases disabling.
Because of the number of people vaccinated, we have more safety data about the COVID-19 vaccines than exists for any other vaccine. The CDC continues to closely monitor COVID-19 vaccines for any safety issues, including problems with manufacturing, a specific lot, or the vaccine itself. If public health experts find any potential safety concerns, FDA and the vaccine manufacturer will work towards a solution.
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.
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.
To make sure that COVID-19 vaccines are safe, CDC expanded and strengthened the country’s ability to monitor vaccine safety. CDC created new ways to gather more information about the safety of COVID-19 vaccines. These web-based platforms give CDC scientists information about the safety of COVID-19 vaccines in real time.
As a result, vaccine safety experts can monitor and detect issues that may not have been seen during the COVID-19 vaccine clinical trials. If any vaccine safety issues—also called adverse events— are reported, CDC scientists can quickly study them and determine if there is a safety concern with a particular vaccine.
To learn more, visit:
In general, the same mRNA vaccine product (i.e., the same manufacturer) should be used for all doses in the primary series, including if you are eligible for an additional primary dose.
CDC has authorized the mix and matching of mRNA vaccines for booster shots for certain individuals; eligible individuals can get any authorized or approved COVID-19 vaccine for their booster dose, regardless of what you received for your primary series.
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.
- What services are there for people who are medically homebound or need help accessing transportation to a vaccination site?
If you or a loved one are in a long-term care or skilled nursing facility, check first to see if they have a vaccine provider serving residents. Mobile vaccination providers may be an option for individuals who are medically homebound, including residents of long-term care, assisted living or group homes, and unable to travel to a pharmacy or vaccination site. For eligibility requirements and a searchable map of mobile providers in your area, go here.
For transportation assistance to a site:
If you are able to get transportation to a pharmacy or clinic, search for the vaccine location closest to you on this map.
If you have misplaced your COVID-19 Vaccination Card after you have been fully vaccinated, you can submit an immunization record request to the Arizona Department of Health Services (ADHS). Record requests are generally processed within 5 to 7 business days; this process may take longer if there is an increase in requests. This form may also be used to request other immunizations on file with ADHS.
Go to the ADHS Immunization Record Request Form (PDF).
NOTE: To potentially access your records faster, ADHS recommends using MyIR Mobile to find your record before submitting an Immunization Record Request form. This service is free. For more information on how to sign up, go here.
No. None of the authorized and recommended COVID-19 vaccines cause you to test positive on viral or diagnostic tests, which are used to see if you have a current infection.
If your body develops an immune response to vaccination, which is the goal, you may test positive on some antibody tests. Antibody tests can indicate if you had a previous infection but not a current one, and a positive antibody test may show you have some level of protection against the virus.
- Where can people call if they don’t have computer access and need help with locating COVID-19 testing or vaccine?
The Maricopa County CARES Team can help with scheduling COVID-19 vaccine and testing appointments over the phone. They can be reached at 602-506-6767 for assistance in English, Spanish, and other languages.
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.
You should get a COVID-19 vaccine even if you already had COVID-19.
Getting a COVID-19 vaccine after you recover from COVID-19 infection provides added protection against COVID-19. People who already had COVID-19 and do not get vaccinated after their recovery are more likely to get COVID-19 again than those who get vaccinated after their recovery. Individuals who have recently been infected with COVID-19 should complete isolation before receiving a COVID-19 vaccination.
If you were treated for COVID-19 with monoclonal antibodies or convalescent plasma while sick with COVID-19, you do not need to wait before getting a COVID-19 vaccine.
Learn more about the benefits of getting a COVID-19 vaccine.
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.
COVID-19 vaccination, including booster doses, is available for free / no charge at events listed on the Maricopa County COVID-19 Events calendar to anyone meeting vaccine eligibility, regardless of insurance or citizenship status.
Before getting vaccinated, visit the provider’s website or call your provider about vaccine availability, eligibility, cost, and insurance requirements.
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.
- For vaccines requiring 2 doses, if I get COVID-19 after my first dose, should I receive the second dose?
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.
It is not recommended you take over-the-counter medicine (such as ibuprofen, aspirin, or acetaminophen) before vaccination for the purpose of trying to prevent vaccine-related side effects. It is not known how these medications might affect how well the vaccine works. If you take these medications regularly for other reasons, you should keep taking them before you get vaccinated. It is also not recommended to take antihistamines before getting a COVID-19 vaccine to try to prevent allergic reactions.
To learn more, visit:
Learn more about medications to relieve post-vaccination side effects.
- If I am up to date on the COVID-19 vaccines, do I still have to quarantine if I’m exposed to someone with COVID-19?
For the general public, quarantine after exposure to someone with COVID-19 is no longer recommended regardless of vaccine status. Everyone who has recently been exposed to someone with COVID-19 should wear a mask around others for 10 full days following exposure and monitor for symptoms of illness.
Please check the CDC website for the most up to date information for what actions you should take if you are exposed to someone with COVID-19.
This guidance does not apply to healthcare professionals and other specific settings. Additional setting-specific guidance and recommendations are available here.
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.
To achieve maximum protection, it is recommended you get your second dose during the recommended time frame.
If you get the second dose later than the recommended time frame, talk to your healthcare or vaccine provider about the timing for the second dose in your primary series.
To achieve the maximum protection, it is recommended you stay up to date on your COVID-19 vaccines.