COVID-19 Vaccine - Facts and FAQs

Vaccine Safety

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

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Authorized Vaccines

Several COVID-19 vaccines have been authorized by the U.S. Food and Drug Administration (FDA).  While all COVID-19 vaccines continue to be safe and effective and reduce your risk of severe illness from COVID-19, CDC recommends receiving an mRNA vaccine (Pfizer or Moderna) over a Johnson & Johnson vaccine. 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.

  Approved for Ages Type 
Doses Needed in Primary Series 
Time Between Doses  Is an Additional Dose Advised for Severely Immunocompromised?
Is a Booster Dose Recommended?
Vaccine Fact Sheet 
Pfizer *  12+ mRNA 
21 Days Yes, at least 4 weeks after 2nd dose for certain groups Yes for anyone 16 or older ≥5 months after 2nd dose in primary series Pfizer-BioNTech Vaccine Fact Sheet for 12+ (Español

Pediatric Pfizer 5-11 mRNA
21 Days Yes, at least 4 weeks after 2nd dose for certain groups No current recommendation Pfizer-BioNTech Pediatric Vaccine Fact Sheet for Ages 5-11
Moderna  18+ mRNA
28 Days  Yes, at least 4 weeks after 2nd dose for certain groups  Yes for anyone 18 or older ≥5 months after 2nd dose in primary series Moderna Vaccine Fact Sheet (Español
Johnson and Johnson  18+ Viral Vector
N/A No current recommendation Yes for anyone 18 or older ≥2 months after first vaccination Johnson and Johnson (Janssen Biotech) Vaccine FDA Fact Sheet 

* On Aug. 23, 2021, the Pfizer COVID-19 vaccine was granted full approval for ages 16 and up by the FDA. It is still under emergency use authorization for all other approved eligibility groups

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Dosing Recommendations

Two Dose Series: Pfizer (ages 12+), pediatric Pfizer (ages 5-11), or Moderna

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.

If you received the Pfizer vaccine:

  •  You’ll need to return for a second dose vaccination 21 days later.

If you received the Moderna vaccine:

  •  You’ll need to return for a second dose vaccination 28 days later.

You should get your second shot as close to the recommended 3-week or 4-week interval as possible. However, your second dose may be given up to 6 weeks (42 days) after the first dose, if necessary. You should not get the second dose early. There is currently limited information on the effectiveness of receiving your second shot earlier than recommended or later than 6 weeks after the first shot. View CDC website for more information.

Getting the second dose is important to getting the full protective benefits of the vaccine, so schedule it as soon as you are able.

It takes about two weeks after being fully vaccinated to achieve full protective benefits from any COVID-19 vaccine.

Recommendations for Third Dose in Significantly Immunocompromised People

CDC recommends that significantly immune compromised individuals who got the Pfizer or Moderna vaccine get an additional dose after the initial two doses. There should be at least 28 days since the last mRNA dose was administered. For a list of conditions and recommendations, visit CDC website.

Single Dose: 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.

The FDA and CDC have not approved nor recommended additional doses for significantly immunocompromised for recipients of the Johnson & Johnson vaccine. There is not enough data at this time to determine whether immunocompromised people who received the Johnson & Johnson’s Janssen COVID-19 vaccine also have an improved antibody response following an additional dose of the same vaccine.

It takes about two weeks after being fully vaccinated to achieve full protective benefits from any COVID-19 vaccine.

Booster Doses

Boosters are recommended for Pfizer, Moderna, and Johnson and Johnson vaccines, based on eligibility. For information on who boosters are recommended for and when to administer them, go here

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Frequently Asked Questions

Children & Teens

The Pfizer vaccine is the only one that has been granted an emergency use authorization (EUA) for children ages 5-11. There are more steps before it can get full approval. Other vaccine manufacturers have vaccines in clinical trials for younger children, but only Pfizer is currently authorized for use in this age group.

The dosage for kids ages 5-11 is one-third of the adolescent (12-17) and adult dose. If you are unsure which option a provider is offering, be sure to ask.

If your child is 5 to 11 years old, then the COVID-19 vaccine dose they will get is very small — just 10 micrograms (or one-third of the dose for older ages). Clinical trials found that this small amount is all it takes to prepare the immune system so it can stop germs from making someone sick.

Children will need two doses of the Pfizer vaccine, at least 21 days apart. They will be considered fully protected two weeks after their second dose. When a child is fully immunized, they do not have to quarantine after contact with a person with COVID-19.

The COVID-19 vaccine clinical trial had more than 2,000 children. Researchers studied how well the vaccine worked in 5- to 11-year-olds. They also looked at data on how well the vaccine worked in 16- to 55-year-olds. Results showed children had the same immune response from the smaller dose and fewer minor side effects.

The COVID-19 vaccination effort is being monitored more closely than any public health initiative in U.S. history. CDC, the American Academy of Pediatrics (AAP), and the National Association of Pediatric Nurse Practitioners recommend that children age 5 and older get vaccinated against COVID-19. If you have questions or concerns, talk to a healthcare professional.

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, the COVID-19 vaccines don't affect puberty or a child or teen's reproductive development in any way. There has been no evidence of vaccines impacting fertility or reproductive health in children or adults. Experts in the field recommend vaccination of all eligible individuals. Read more on this topic.

Dosages are determined by age, not a child’s size or weight. Some children may be 11 years old when they get their first dose and 12 at the time of their second dose. They should receive the dose recommended for their age on the day of vaccination, according to the CDC.

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:

  • Talk to your child before the visit about what to expect. Remind your child that vaccines can keep him or her healthy.
  • Be positive. Getting vaccinated will help your children enjoy activities like sports, choir, and parties with some added confidence that they are protected!
  • Be honest with your child. Explain that shots can pinch or sting, but that it won’t hurt for long.
  • Avoid telling scary stories or making threats about shots.
  • Engage other family members, especially older siblings, to support your child. This might include multiple family members getting vaccinated at the same time so younger kids can see it’s ok.
  • Pack your child’s favorite toy, book, or blanket or create a favorite music playlist to comfort him or her during the vaccination.


Yes. Research has not yet shown how long you are protected from getting COVID-19 again after you recover from COVID-19. Getting vaccinated will help protect your child from getting sick with COVID-19 again, including the Delta variant and future variants. Plus, getting fully vaccinated will help prevent serious illness or hospitalization if they do get infected again.

Evidence is emerging that people get better protection by being fully vaccinated compared with having had COVID-19. One study showed that unvaccinated people who already had COVID-19 are more than 2 times more likely than fully vaccinated people to get COVID-19 again.

COVID-19 Variants

Multiple variants of the virus that causes COVID-19 have been documented. The Omicron variant is a new strain detected first in South Africa in November, and is now circulating in most continents except Central and South America. On November 26, 2021, the WHO classified this as a variant of concern.

Key things to know:

  • The first known case of the Omicron variant in the U.S. was reported in California on Dec. 1.
  • The Omicron variant contains more mutations than previous strains, which might lead to increased transmission and ability to infect people who have been previously infected and those who are vaccinated.
  • We do not know if Omicron is more or less severe than other COVID-19 strains.
  • While effectiveness of the existing vaccines against the Omicron variant is still being studied, vaccination and boosters remain the best line of defense against severe illness from COVID-19. Find a vaccine site
  • CDC is performing enhanced surveillance to identify this strain in the US using the National SARS COV-2 Surveillance system

The Delta variant is significantly more contagious than the original strain of COVID-19. Mutations like Delta occur when not enough people are vaccinated, and spread is allowed to continue. While just over half of Maricopa County residents have gotten at least 1 dose of vaccine, it's a good start, but we're a long way off from stopping Delta and future variants. We need to continue increasing vaccinations to reduce spread and prevent more variants from taking hold.

The Delta variant is a strain of the virus that causes COVID-19 that is more contagious than other strains of COVID-19. This means it spreads from person-to-person more easily, especially if a person is not vaccinated.

Additional facts to know:

  • As of July 2021, the Delta variant has become the “dominant variant” in the United States, which means that most of the new COVID-19 cases that are being analyzed are caused by the Delta variant.
  • People who have not been fully vaccinated for COVID-19 are most at risk of getting the Delta variant, and possibly becoming more seriously ill.

Based on what we know, the Delta variant is spread more easily from person-to-person, which is why it is important that everyone 12 years and older get fully vaccinated as soon as possible. There is also some evidence that the illness caused by the Delta variant may be more severe, particularly in younger people, but there is still a lot to learn about this variant.

If you have not already been fully vaccinated for COVID-19, you should get vaccinated as soon as possible. Vaccine is widely available and free of charge in Maricopa County.

  • Getting vaccinated is especially important for younger people, as the Delta variant impacts young people in a potentially more severe way than previous variants.
  • It is critical to get BOTH doses of the two-dose series (Moderna and Pfizer) as one dose is not nearly as protective against the Delta variant.
  • Use the COVID-19 vaccine locations map to find a vaccine near you at your local pharmacy, grocery store, clinic, or pop up event. You can also find information about what brand(s) of vaccine are offered at each location:

People who are vaccinated are more protected from the Delta variant than those who are unvaccinated; however, people who are vaccinated can still become infected and possibly infect others.

CDC, ADHS, and MCDPH recommend that all people wear a mask, regardless of vaccination status, when in indoor public settings in areas of substantial or high community transmission. View our current community transmission rate on our dashboard at

Please see additional Delta variant FAQs.

Booster Shots and Additional Third Doses

Boosters are recommended if:

  • You received the second dose of Pfizer at least six months ago, AND you are age 16 or older.
  • You received the second dose of Moderna at least six months ago, AND you are age 16 or older.
  • You received Johnson & Johnson vaccine at least two months ago and are age 18 or older

Your booster dose may be either the same type of COVID-19 vaccine for your booster or a different COVID-19 vaccine. While all three vaccine types continue to be safe and effective and reduce your risk of severe illness from COVID-19, CDC recommends receiving an mRNA vaccine (Pfizer or Moderna) over a Johnson & Johnson vaccine.Learn more.

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.

The COVID-19 vaccines authorized in the United States continue to be remarkably effective in reducing risk of severe disease, hospitalization, and death, even against the widely circulating Delta variant.

Although we continue to see stable and highly effective protection against hospitalizations and severe outcomes for people who are fully vaccinated, we are seeing a decrease in vaccine effectiveness against infections overall. This decline coincides with the increase in the Delta variant in the United States, along with relaxation of masking and physical distancing recommendations.

Nursing home residents were prioritized for COVID-19 vaccination early in the U.S. vaccination program and might be among the first groups to show evidence of potential waning of the immunity provided by vaccines. A recent study showed among nursing home residents, in the pre-Delta period, two doses of mRNA vaccine were 75% effective against COVID-19 infections; but during the Delta period, mRNA vaccine effectiveness declined to 53%.

Ongoing studies will determine if additional booster doses will be needed to maintain immune protection in the future.

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 recommends that people with moderately to severely compromised immune systems receive an additional dose of mRNA COVID-19 vaccine at least 28 days after a second dose of Pfizer-BioNTech COVID-19 vaccine or Moderna COVID-19 vaccine.

This includes people who have:

  • Been receiving active cancer treatment for tumors or cancers of the blood
  • Received an organ transplant and are taking medicine to suppress the immune system
  • Received a stem cell transplant within the last 2 years or are taking medicine to suppress the immune system
  • Moderate or severe primary immunodeficiency (such as DiGeorge syndrome, Wiskott-Aldrich syndrome)
  • Advanced or untreated HIV infection
  • Active treatment with high-dose corticosteroids or other drugs that may suppress your immune response

If the mRNA vaccine product given for the first two doses is not available or is unknown, either mRNA COVID-19 vaccine product may be administered.

At this time, CDC does not have a recommendation for immunocompromised people to receive both a booster shot and an additional dose. 

People should talk to their healthcare provider about their medical condition, and whether getting an additional dose is appropriate for them.

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 dose. 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.

The FDA’s recent EUA amendment only applies to mRNA COVID-19 vaccines, as does CDC’s recommendation.

Emerging data have demonstrated that immunocompromised people who have low or no protection following two doses of mRNA COVID-19 vaccines may have an improved response after an additional dose of the same vaccine. There is not enough data at this time to determine whether immunocompromised people who received the Johnson & Johnson’s Janssen COVID-19 vaccine also have an improved antibody response following an additional dose of the same vaccine.

For more on this topic, see the CDC website.


Medical Conditions and Other Considerations

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.

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 studyof 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 diseaseadversely 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.

Effective August 13, 2021, CDC recommends that people who are moderately to severely immunocompromised receive an additional dose of an mRNA COVID-19 Vaccine (Pfizer-BioNTech or Moderna) at least 28 days after the completion of the initial mRNA COVID-19 vaccine series.

Read more on the CDC website.

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.

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

Vaccine Safety

Federal health officials are monitoring very rare occurrences of myocarditis and pericarditis after vaccination with mRNA vaccines (Pfizer and Moderna). Key things we know from studies to date:

  • Majority of cases have occurred in male adolescents and young adults under age 30 (ages 12-29)
  • Occurs more often after the second dose of vaccine, usually within a week of vaccination
  • The vast majority of cases have been mild and for a short time, with patients recovering after a few days.
  • CDC and its partners are actively monitoring reports of myocarditis and pericarditis after COVID-19 vaccination.

Although the risk is small, 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.

It’s important to note that while also rare, a COVID-19 infection is more likely to cause heart inflammation than a vaccine. According to a recent large-scale study, the risk of myocarditis among people of any age was almost 16 times higher for people infected with COVID-19 compared to those who aren’t infected. The myocarditis risk is 37 times higher for infected children under 16.

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.

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. Learn more about mRNA COVID19 vaccines.

Learn more about mRNA COVID-19 vaccines.

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.

Learn about the Johnson and Johnson vaccine.

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.

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.


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.

Clinical Trials

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.

General Topics

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 have AHCCCS, ALTCS, or another insurance provider: Check with your insurance company to see if they can provide you with medical transportation to an existing vaccine site.
  • If you are age 60 or older: contact the Area Agency on Aging at 602-264-4357 for transportation options to an existing 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; however, due to an increase in requests, this process may take longer. This form may also be used to request other immunizations on file with ADHS.

Go to the ADHS Immunization Record Request Form.

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 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.

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.

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 and variants is possible, you should be vaccinated regardless of whether you already had COVID-19 infection. Research on pre-existing immunity and mRNA vaccines shows (see published study) that individuals who are vaccinated after recovering from COVID-19 had 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.

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.

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.

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.

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.

See the CDC guidance for those who are fully vaccinated reguarding quarantine.


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.

Check with your vaccine provider about how to get scheduled for your second dose. Some providers may schedule at your first dose appointment, others may notify you with an email reminder to register for a second dose appointment.

While it is recommended you have your second dose where you received your first, we know that may be difficult if appointments are limited or not available at these sites. Maricopa County is working with our health system partners, retail pharmacies and other vaccinators to establish vaccination events and access points to provide second doses to individuals. Most important is that you schedule your second dose at a location that provides the same manufacturer of vaccine as your first dose [All of the PODs use Pfizer vaccine]. At your first dose appointment, you should receive a vaccine card that tells you the kind of vaccine you received and the date it was administered. Depending on the type of vaccine, you'll need a second dose 21 days (Pfizer) to 28 days (Moderna) later. Your second dose must be of the same vaccine.

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. During the enrollment process, AZDHS verifies each provider’s ability to receive, store, handle, and administer vaccine.


Johnson & Johnson

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:

  • Weakness or tingling sensations, especially in the legs or arms, that’s worsening and spreading to other parts of the body
  • Difficulty walking
  • Difficulty with facial movements, including speaking, chewing, or swallowing
  • Double vision or inability to move eyes
  • Difficulty with bladder control or bowel function

On July 12th, the FDA announced a new warning on the Johnson & Johnson COVID-19 vaccine and a possible link to Guillain-Barré. The agency revised the vaccine's accompanying fact sheets to reflect an increased risk of the disorder following vaccination.

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,
  • backache,
  • 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

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.


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