COVID-19 Vaccine FAQs

Since COVID-19 vaccinations first became available to the public in early January 2021, millions of Americans have been vaccinated. What began in limited supply is now available in Arizona to anyone over the age of 18, and in some cases, those as young as 6 months.

At Arizona State University, we encourage faculty, staff and students to get the COVID-19 vaccination in whatever brand is available to you. To accelerate that process, ASU has on-campus distribution that serves the ASU community. ASU Health Services and Employee Health have COVID-19 vaccines, third doses and boosters available. Students and employees can begin that process through the ASU point-and-click health portal.

In addition, vaccinations are now available at more places than ever before, including pharmacies, physician’s offices and the state or county.

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FDA authorizes 2nd booster for people 50 and older

FDA authorizes 2nd booster for people 50 and older

Older adults will be eligible for a second COVID-19 booster shot under a decision by federal health regulators, who are expected to authorize the additional shots for the broader population in the fall.


Understanding COVID-19 variants and vaccines’ effectiveness

Learn how these variants evolve and whether the current vaccines are effective at protecting people from serious illness or death.


COVID-19 vaccine testing turns to kids

Researchers are beginning to test younger and younger kids to make sure COVID-19 vaccines are safe and work for each age.

Frequently asked questions

We know you may have questions about the vaccine, including how it works, who is eligible and why it is important to get it. We have assembled the following list to address some of the most common questions about the vaccine.

Getting the vaccine

  1. The vaccine lowers your risk of catching COVID-19. Even though some vaccinated people do get breakthrough infections, they are far less common than infections among unvaccinated people.
  2. If you do get sick, it won’t be as bad. Vaccinated people who get infected almost always have a mild or asymptomatic case.
  3. The vaccines are safe, but getting COVID-19 isn’t. Out of all the people who catch COVID-19:
    • 1 in 5 end up in the hospital.
    • At least 1 in 10 experience long-term health problems.
    • 1 in 50 die. 

For those in the ASU community, ASU Health Services and Employee Health have COVID-19 vaccines, third doses and boosters available.

Students can make appointments by going to the ASU Health Portal; ASU Health Services has the Moderna and Johnson & Johnson vaccines available.

ASU employees can make appointments through Employee Health; Employee Health has the Moderna vaccine only.

All COVID-19 vaccines are widely available across pharmacies, supermarkets and medical providers. To find a convenient location near you to get a COVID-19 vaccine dose or booster, please visit vaccines.gov/search or azdhs.gov/FindVaccine. You can also call 1-800-232-0233 (TTY 1-888-720-7489).

Refer to the CDC or FDA for the most current information on the COVID-19 vaccine dose, and booster details and timing.

For the most part, yes (see below for exceptions). The Centers for Disease Control and Prevention recommend that everyone be offered the vaccine, regardless of whether they have been infected. It is unclear how long natural immunity lasts after someone recovers from an infection.

There is guidance on exceptions from the CDC on the following:

Those with known current COVID-19 infection: Vaccination should be deferred until the person has recovered from the acute illness (if the person had symptoms) and criteria have been met for them to discontinue isolation. This recommendation applies to people who develop a COVID-19 infection before receiving any vaccine doses, as well as those who develop an infection after the first dose but before receipt of the second one.

Those with known COVID-19 exposure: Vaccination is unlikely to be effective in preventing disease after an exposure — because the median incubation period of COVID-19 is four to five days, it is unlikely that the first dose of the vaccine would provide an adequate immune response within the incubation period for effective post-exposure prophylaxis (that is, vaccination to prevent the development of COVID-19). People in the community or outpatient setting who have had a known COVID-19 exposure should not seek vaccination until their quarantine period has ended to avoid potentially exposing health care personnel and other persons during the vaccination visit. 

Those who have received passive antibody therapy (that is, who have received monoclonal antibodies or convalescent plasma from individuals who have recovered from an infection): Based on the estimated half-life of such therapies as well as evidence suggesting that reinfection is uncommon in the 90 days after initial infection, vaccination should be deferred for at least 90 days, as a precautionary measure until additional information becomes available, to avoid potential interference of the antibody therapy with vaccine-induced immune responses. This recommendation applies to people who receive passive antibody therapy before receiving any vaccine doses as well as those who receive passive antibody therapy after the first dose but before the second dose, in which case the second dose should be deferred for at least 90 days following receipt of the antibody therapy. 

There is no recommended minimum interval between other antibody therapies not specific to COVID-19 treatment (e.g., intravenous immunoglobulin, RhoGAM) and vaccination. 

No. Please stay home and reschedule when you are well. It’s important to protect the health of the distribution-site staff, as well as other people receiving the vaccine.

No. Your second vaccination needs to be the same vaccine brand as your first (Moderna or Pfizer-BioNTech).

However, for boosters, you may mix vaccine types. Moderna and Pfizer are preferred, even for those who initially received the Johnson & Johnson vaccine. Learn more here.

You will need to be observed for 30 minutes after your vaccine dose, rather than the standard 15 minutes.

Consult with your health care provider. If you are on blood thinners, you will need to wait 30 minutes under observation at the vaccination site after receiving your vaccine.

Consult with your OB/GYN and/or pediatrician before receiving any COVID-19 vaccine.

The COVID-19 vaccine is free to everyone living in the United States. You do not need to have health insurance. You do not need to be a U.S. citizen.

No. If you have health insurance, you will be asked to enter your information during the vaccine registration.

Yes — time to take the vaccine is considered working time. Employees should try to take it during working hours. Time away from work should be coordinated with and approved by the supervisor with as much notice as possible.

Time should be recorded as regular working time for hourly employees even if it is taken on a weekend and results in overtime. FFCRA pay codes should not be used to account for time to take a vaccine.

For assistance with time reporting questions, contact OHR Partners.

There is no upper age limit for any of the vaccines.

On June 17, 2022, the U.S. Food and Drug Administration granted emergency-use authorization for both the Pfizer and Moderna vaccines for children as young as 6 months.

International students can get the vaccine while in the U.S., and it is recommended that they get the vaccine as soon as they are able to.

No. They should bring verification of vaccination with them so that the vaccination site knows which shot they need. You cannot mix vaccine brands, however. ASU cannot guarantee that if someone gets a certain vaccine elsewhere that the same brand will be available here.

The U.S. will only distribute vaccines that have been approved as effective and have received emergency-use designation. Other countries may be using the same or different vaccines, as there are numerous available globally.

How it works

The SARS-CoV-2 virus is covered in a crown, or corona, of spike proteins that give coronaviruses their name. The viruses use these spike proteins like keys to get into human cells.

There are currently three types of COVID-19 vaccines authorized for use in the U.S. — adenovirus, protein subunit and messenger RNA (mRNA) vaccines. While each vaccine type employs a different delivery mechanism, the end result is the same: the immune system is trained to recognize these spike proteins and prepare to defend against them.

Both the adenovirus and mRNA vaccines use the virus’s genetic instructions for building spike proteins to provoke an immune response.

The Johnson & Johnson vaccine contains a common virus called an adenovirus. The virus has been reprogrammed so that it can’t replicate or make you sick. Instead, it carries DNA with instructions for the coronavirus’s spike protein.

When your cells absorb the adenovirus, they copy the instructions for the spike protein into messenger RNA molecules. The cells use this mRNA like a blueprint to start building spike proteins. The spike proteins make their way to the outside of the cell, where your immune system recognizes them as intruders and mobilizes an immune response.

The Pfizer-BioNTech and Moderna vaccines work in a similar way, but they skip the adenovirus step. Instead of having your cells build the mRNA from DNA, these vaccines give you the mRNA directly.

Unlike the other two vaccine types, Novavax’s protein subunit vaccine directly injects a version of the spike protein along with an ingredient called an adjuvant. The adjuvant stimulates the immune system to produce more antibodies and T-cells. This is a more traditional vaccine design and has been in use in the United States for more than 30 years.

In all cases, no genetic material from the COVID-19 remains. In the adenovirus and mRNA vaccines, the genetic instructions are destroyed after use, like a self-destructing “Mission Impossible” message. In the protein subunit vaccine, the spike protein is a laboratory-formulated nanoparticle that contains no genetic material and cannot cause disease.

However, the antibodies created by your immune system remain. If you’re exposed to the coronavirus in the future, your body will recognize the spike protein trying to invade your cells and deploy antibodies in defense.

They are working extremely well.

“The intended benefit of the vaccines was to prevent serious illness and death. They are excellent at doing that,” says Josh LaBaer, MD, executive director of the Biodesign Institute at ASU.

The CDC reports that the COVID-19 vaccines continue to provide strong protection against severe disease, hospitalization and death in adults, even during variant surges. Protection is reported to be strongest among adults who received all recommended boosters.

Common side effects of the COVID-19 vaccines include fever, chills, fatigue, headache, and pain and swelling at the injection site. But those side effects are short-lived and not cause for concern.

“That's a great sign. Symptoms show that your body is creating an immune response to COVID,” says Heather Ross, a clinical assistant professor in ASU’s Edson College of Nursing and Health Innovation and School for the Future of Innovation in Society. She participated in the Moderna vaccine clinical trial in summer 2020.

“After the first dose, my arm was pretty sore and I had a headache, but not anything serious. After my second dose, about eight hours after the shot I had a fever, I felt super tired and pretty grumpy for about 30 hours. And then I was fine,” she says.

“I do tell people, vaccination symptoms are a hell of a lot better than getting sick with COVID. I have students, healthy young people, who are still getting short of breath when they try to exert themselves, months after recovering. It can be really, really disabling. We’ve seen people getting strokes after the fact from having COVID. It's really scary stuff.” 

There have been some extremely rare, more severe side effects from the vaccines. These include allergic reactions, blood clots after the Johnson & Johnson vaccine, and myocarditis and pericarditis in adolescents/young adults after the mRNA vaccines. Get up-to-date information about reported side effects here.

It is important to remember that your risk of catching and dying from COVID-19 is far higher than the risk of any of these side effects.

Yes, employees who have side effects can use sick leave.

No. There are no known long-term effects from the COVID-19 vaccines used in the U.S. 

More than 356 million doses have been given under the most intense safety monitoring in our country’s history. Anyone can report reactions through the Vaccine Adverse Events Reporting System. The CDC, Food and Drug Administration and other federal agencies investigate these reports thoroughly. They have not found any long-term problems caused by the COVID-19 vaccines. 

This matches what we know about vaccines in general.

“The overwhelming majority of vaccine side effects show up within two months,” says Anna Muldoon, who holds a master’s degree in public health and is a PhD student in the School for the Future of Innovation and Society. “People don't get weird effects from a vaccine 10 years later. The body doesn't work like that.”  

“I don't worry so much about long-term negative consequences, because we know they are really nonexistent in vaccines. And there's no reason to believe that this vaccine is going to be different from any others,” adds Bertram Jacobs, a professor of virology with the School of Life Sciences and a researcher in the Biodesign Center for Immunotherapy, Vaccines and Virotherapy.

On the other hand, COVID-19 is known to have serious, long-term health risks.

“Between 15% to 60% of people have long-term side effects of the virus, even people who had mild or asymptomatic infections,” says Josh LaBaer, MD, executive director of the Biodesign Institute at ASU. “Brain fog, memory problems, respiratory problems, gastrointestinal problems — these are showing up more and more. We now know in no uncertain terms that this virus gets into the brain.”

“If you’re worried about long-term side effects, there’s much more case for having them from the virus than from the vaccine. It’s naive to assume that when you get over the virus you’re done with it,” he adds.

The Pfizer-BioNTech and Moderna vaccines contain messenger RNA (mRNA), lipids and saline solutions. The single active ingredient — mRNA — is contained within a protective bubble of lipids. The saline solutions in the two vaccines are used commonly in medications and vaccines and serve to keep the pH and salt levels of the mixture close to those in the human body. Both vaccines are essentially genetic material wrapped in a bubble of fat suspended in salt water.

The full ingredients of the Moderna COVID-19 vaccine are: messenger ribonucleic acid (mRNA), four lipids: SM-102; polyethylene glycol (PEG) 2000 dimyristoyl glycerol (DMG); cholesterol; 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC); and the saline solutions comprised of tromethamine, tromethamine hydrochloride, acetic acid, sodium acetate, and sucrose.

The full ingredients of the Pfizer-BioNTech COVID-19 vaccine are: messenger ribonucleic acid (mRNA), four lipids: (4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate); 2-[(polyethylene glycol)-2000]-N,N-ditetradecylacetamide; 1,2-Distearoyl-sn-glycero-3-phosphocholine and cholesterol; and a saline solution of potassium chloride, monobasic potassium phosphate, sodium chloride, dibasic sodium phosphate dihydrate, and sucrose.

The Johnson & Johnson vaccine contains a modified adenovirus with coronavirus DNA, as well as various stabilizers, alcohol for sterilization, an anticoagulant, an emulsifier to hold the ingredients together and salt.

The full ingredients of the Johnson & Johnson vaccine are: recombinant, replication-incompetent adenovirus type 26 expressing the SARS-CoV-2 spike protein, citric acid monohydrate, trisodium citrate dihydrate, ethanol, 2-hydroxypropyl-β-cyclodextrin (HBCD), polysorbate-80 and sodium chloride.

The Novavax vaccine contains a spike protein of the virus that causes COVID-19, lipids to help the spike protein enter the cells, and an adjuvant. The adjuvant prompts the immune system to respond to the spike protein. It also contains salts, sugar and acid to stabilize the vaccine during manufacturing, shipment and storage. 

The full ingredients of the Novavax vaccine are: SARS-CoV-2 recombinant spike protein, cholesterol, phosphatidylcholine, Fraction-A and Fraction-C of Quillaja saponaria Molina extract, disodium hydrogen phosphate heptahydrate, disodium hydrogen phosphate dihydrate, polysorbate-80, potassium chloride, potassium dihydrogen phosphate, sodium chloride, sodium dihydrogen phosphate monohydrate, sodium hydroxide or hydrochloric acid, and water.

Polyethylene glycol, or PEG, is a petroleum-derived compound that’s found in everything from medicine and food to cosmetics and industrial products. PEG is in both the Pfizer-BioNTech and Moderna vaccines, where it’s used as a stabilizing agent for the mRNA.

“It’s used in the vaccines to make sure the active component doesn't fall apart, dry up, degrade or become unusable until it gets delivered to the body,” says Biodesign Institute Executive Director Josh LaBaer. “It’s used in all kinds of substances that we take all the time. Generally speaking, the vast majority of people have no problem with polyethylene glycol, but there are individuals that have allergic reactions to PEG.”

The Johnson & Johnson vaccine does not contain PEG, but it does contain polysorbate. A small number of people are allergic to polysorbate.

If you have a history of severe allergic reactions, check the CDC guidelines to see if you should receive a COVID-19 vaccine.

No. The flu shot does not protect against COVID-19.

Health experts urge people to get their annual flu shot in addition to the COVID-19 vaccine. Especially with so many hospitals at capacity, it's best to do everything possible to prevent either illness.

It’s possible. Breakthrough infections — cases of COVID-19 in vaccinated people — are rare. However, there has been an increase in breakthrough infections from first the delta variant and now omicron. 

“First, no vaccine is perfect. We know that some percent of people don’t mount as strong an immune response,” says Josh LaBaer, MD, executive director of the Biodesign Institute at ASU. 

Vaccines produce antibodies that fight the virus. Over time, the antibodies decrease, but our immune systems also have memory B cells that remember how to make them. When memory B cells are exposed to the virus, they start making more antibodies, but this can take a few days. 

There is some evidence that people with breakthrough infections have high levels of virus at the start, before their B cells kick in and get the virus under control. That may be why vaccinated people tend to have mild cases — their memory B cells churn out antibodies before the infection gets out of control. But they could be contagious before this happens.


While the vaccines contain genetic material (mRNA), they have no effect on our DNA. These messenger RNA vaccines, or mRNA, simply deliver instructions to our immune cells to make a single protein from the coronavirus. Once the protein is created, those instructions are broken down and the protein piece is displayed on the surface of a cell. Our immune systems recognize that it doesn’t belong and make antibodies in defense, mirroring the natural immune response to an infection.

The mRNA does not remain in the body. It’s disposed of once it delivers its instructions and does not impact our DNA.

With the protein subunit vaccine, no genetic material is introduced at all. The vaccine uses a version of the spike protein created in a laboratory and does not contain genetic material.

It is unknown if the COVID-19 vaccines will protect against new strains of SARS-CoV-2. Preliminary research suggests yes.

Pfizer-BioNTech and Moderna vaccines prompt the body to create antibodies tailored to the virus’s spike protein, and new strains of the coronavirus are exhibiting changes to that region.

Scientists don’t think those changes will be enough to prevent the vaccine from working. “What we might see, though, is instead of being 95% effective, maybe the vaccines are 80% effective or 70% effective against the new strains,” says Bertram Jacobs, a professor of virology with ASU’s School of Life Sciences and a researcher in the Biodesign Institute's Center for Immunotherapy, Vaccines and Virotherapy.

While diminished efficacy is a concern, Jacobs says both the Pfizer-BioNTech and Moderna vaccines can be quickly adapted to protect against emerging strains.

“It is worth noting that even though the vaccines have not yet been formally tested on the variants, they are still proving effective when measured in geographical areas that have high rates of variants,” adds Biodesign Institute Executive Director Josh LaBaer, pointing to the Johnson & Johnson clinical trial in South Africa.

In the trial, 92% of sequenced cases were the more infectious South African variant of the virus, though the vaccine proved effective in preventing moderate to severe COVID-19 73% of the time at 14 days and 82% at 28 days.

“My guess is that the vaccines are going to be effective for a long time,” says LaBaer. “I'm hopeful, because this is not like the flu virus, which constantly changes its look and its antigens. This virus doesn't change that fast, and the vaccines seem to be pretty broadly effective.”

After the vaccine - Continued safety protocols

Testing is vital to fight the spread of COVID-19. People are encouraged to test regularly, but especially if they have symptoms or have been exposed to someone who tested positive.

ASU offers free, saliva-based PCR testing to all students, faculty and staff, as well as to dependents of benefits-eligible employees. Find a free COVID-19 test near you.

It’s important to continue to get tested. If you’ve recently received a COVID-19 vaccine, this will not affect your COVID saliva test result. You will still receive an accurate test result.

The saliva test measures the virus itself — its genetic material, its RNA — and does not have anything to do with the immune system. So nothing about the vaccination would affect that kind of test. If someone is currently infected with virus, whether or not they have been vaccinated, ASU's saliva test will work.


COVID-19 health protocols

As of March 14, 2022, face coverings will be recommended but not required starting across campus in counties that are low to medium risk. Signs will be placed in areas where face coverings are still required, such as in health care settings and shuttles. In addition, the Daily Health Check will become optional starting March 14.

The university continues to expect the ASU community to stay up to date on COVID-19 vaccines and to get tested regularly, especially for those experiencing symptoms. Please avoid crowds when possible, wash your hands often, cover your coughs and sneezes, clean and disinfect frequently touched surfaces daily, monitor your health daily and stay home when sick.

This site reflects current public health guidance and is subject to change, and ASU will continue to proactively communicate changes as they arise.

Information compiled with the help of:

  • Bertram Jacobs, a professor of virology with the School of Life Sciencesand a researcher in the Biodesign Institute's Center for Immunotherapy, Vaccines and Virotherapy. He has been working with vaccines for more than 25 years and is one of the world’s foremost experts on a poxvirus called vaccinia, a cousin of the smallpox virus.
  • Megan Jehn received her doctorate and master's of health science degrees from the Johns Hopkins School of Public Health in clinical epidemiology. She played an integral role in Maricopa County’s Serosurvey and is a member of the Arizona CoVHORT, a collaboration between public health and medical researchers to examine COVID-19’s effects on Arizona
  • Aaron Krasnow, associate vice president of Health Services and Counseling Services. He is responsible for Health and Counseling Services for all ASU campuses as well as leading efforts in ensuring student emotional and psychological well-being, and supervision of ASU Wellness.
  • Josh LaBaer, MD, executive director of ASU’s Biodesign Institute. He is an expert in the study of biomarkers — unique molecular signifiers of disease — in pursuit of finding early warning signs of illness like diabetes and cancer.
  • Frank LoVecchio, DO, medical director of clinical research for ASU's College of Health Solutions. He is principal investigator for the Infectious Disease Network studies, a group of emergency departments funded through the CDC to conduct infectious disease trials
  • Anna Muldoon, who holds a master’s degree in public health and is a PhD student in the School for the Future of Innovation and Society studying the relationship between infectious disease outbreaks and social crisis in the United States. She currently works in Biodesign’s Modeling Emerging Threats for Arizona (METAz).
  • Heather Ross, a nurse practitioner and clinical assistant professor in ASU’s Edson College of Nursing and Health Innovation and School for the Future of Innovation in Society. She also participated in the Moderna vaccine clinical trial over the summer.

Still have questions after reading this FAQ?

Reach the ASU Experience Center (help desk) at 1-833-525-0610.

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