COVID-19 Vaccine

Your Questions Answered


Do you have questions about the COVID-19 vaccine?
You aren’t alone.

We’ve answered some of the most frequently asked questions about the vaccine below, including information about booster shots and the vaccine for children.

Remember to always consult with your primary care provider to determine the best decision regarding your and your family’s health.

Information on this page was accurate at the time of original publication. Because information about COVID-19 changes quickly, we encourage you to visit the websites of the Centers for Disease Control & Prevention (CDC), City of San Antonio COVID-19, and Texas Department of State Health Services.


December 9, 2022 (CDC Update): CDC recommends everyone stay up to date with COVID-19 vaccination, including all primary series doses and boosters for their age group:

  • People ages 6 months through 4 years should get all COVID-19 primary series doses.
  • People ages 5 years and older should get all primary series doses, and the booster dose recommended for them by CDC, if eligible.

There is no booster recommendation for children aged 6 months–4 years who got the Pfizer-BioNTech COVID-19 vaccine primary series.


Prevention & Testing

Find a list of free testing locations and updated quarantine guidelines on our COVID-19 Prevention, Testing, & Resources page.

Is the new XBB1.5 subvariant more dangerous than other COVID-19 variants?

The XBB1.5 variant currently makes up more than half of U.S. COVID-19 cases. According to experts, XBB.1.5 can infect people who have enough antibodies to block other strains because it grows where other strains can’t.

The good news is that the symptoms and severity of COVID-19 for individuals infected with the XBB.1.5 do not seem to be different than what we are already seeing. 

Updated COVID boosters cut the infection risk from XBB.1.5 subvariant by nearly half, CDC finds. The best thing most people can do to protect themselves is to be vaccinated and boosted. 

Learn more about XBB1.5 from University Health expert Jason Bowling. MD.

Who should get the COVID-19 vaccine?

The CDC recommends that people ages 6 months through 4 years should get all COVID-19 primary series doses.

Booster recommendations vary by age group. Find more information below or review the CDC COVID-19 Vaccine Guidelines.

Do I need a COVID-19 booster shot?

CDC recommends one updated (bivalent) booster dose:

  • For everyone aged 5 years and older if it has been at least 2 months since your last dose.
  • For children aged 6 months4 years who completed the Moderna primary series and if it has been at least 2 months since their last dose.

There is no booster recommendation for children aged 6 months to 4 years who got the Pfizer-BioNTech COVID-19 vaccine primary series.

Boosters are an important part of protecting yourself from getting seriously ill or dying from COVID-19. They are recommended for most people. You can also use this tool to determine when or if you (or your child) can get one or more COVID-19 boosters.

What is the difference between the monovalent and bivalent booster shot?

The updated (bivalent) boosters are called “bivalent” because they protect against both the original virus that causes COVID-19 and Omicron variants.

Previous boosters are called “monovalent” because they were designed to protect against the original virus that causes COVID-19. They also provide some protection against Omicron, but not as much as the updated (bivalent) boosters.

The virus that causes COVID-19 has changed over time. The different versions of the virus that have developed over time are called variants. Learn more about variants of the COVID-19 virus.

Two COVID-19 vaccine manufacturers, Pfizer and Moderna, have developed updated (bivalent) COVID-19 boosters.

What are the different types of vaccines available?

Currently, there are four COVID-19 vaccines authorized by the FDA categorized into three main types: (1) mRNA, (2) viral vector, and (3) protein subunit. Each type of vaccine prompts our bodies to recognize and help protect us from the virus that causes COVID-19.

mRNA Vaccines (Pfizer & Moderna)

The Pfizer and Moderna vaccines use Messenger RNA (mRNA) technology. Essentially, using an mRNA vaccine, we trick our own cells into developing an immune response to COVID-19 which can protect us against a real infection in the future. Both the Pfizer and Moderna vaccines are given in two doses. You need both doses of the vaccine for it to be fully effective.

Protein Subunit Vaccines (Novavax)

Protein subunit vaccines like Novavax contain pieces (proteins) of the virus that causes COVID-19. These virus pieces are the spike protein. The vaccine also contains another ingredient called an adjuvant that helps the immune system respond to that spike protein in the future. Once the immune system knows how to respond to the spike protein, the immune system will be able to respond quickly to the actual virus spike protein and protect you against COVID-19.

Viral Vector (Johnson & Johnson)

The Johnson & Johnson vaccine uses a modified version of a different virus (a vector virus) to deliver important instructions to our cells.

What makes the Novavax different than the other COVID-19 vaccines?
  • The Novavax vaccine is a traditional one compared to the other vaccines. Its technology has been used before in vaccines to prevent such conditions as shingles, human papillomavirus, and DTaP (diphtheria, tetanus, and pertussis), among others.
  • Novavax directly injects a version of the spike protein, along with another ingredient that also stimulates the immune system, into the body, leading to the production of antibodies and T-cells.
  • The vaccine was found to be 90% effective against mild, moderate, and severe disease
  • Novavax is approved for ages 12 and up
  • Its effectiveness against Omicron and its subvariants is unknown
What are the authorized ages for each vaccine?
6 months to 4 years 3 doses of primary series No booster
5 to 11 years 2 doses of primary series 1 booster dose
12 to 17 years 2 doses of primary series 1 booster dose
18 & older 2 doses of primary series 1 booster dose


6 months to 11 years 2 doses of primary series No booster
12 to 17 years 2 doses of primary series 1 booster dose
18 & older 2 doses of primary series 1 booster dose


12 & older 2 doses of primary series No Novavax booster, Moderna or Pfizer booster recommended for eligible age groups


18 & older 1 dose No Johnson & Johnson booster, Moderna or Pfizer booster recommended for eligible age groups


Where can I/my child get the vaccine?

Getting a COVID-19 vaccine is faster and more convenient than ever. About nine out of 10 Americans live within five miles of a COVID-19 vaccination site.


Click the link to schedule your appointment at local participating pharmacies:

University Health

University Health is currently offering Pfizer vaccines for first COVID-19 vaccination series, and the new Pfizer bivalent vaccines for boosters only, at all of their pharmacy locations free of charge. Novavax vaccines for first COVID-19 vaccination series only at Robert B. Green Campus free of charge.

Your PCP, Pediatrician, & Clinics

All vaccines, including booster shots, may be available at your PCP, your child’s pediatrician, or local vaccination centers in your neighborhood.

Pop-up Clinics
Click here for an updated list of vaccine pop-up clinics located in and around San Antonio.

What do we know about the vaccine's safety?

While COVID-19 vaccines were developed rapidly, all steps have been taken to ensure their safety and effectiveness. Bringing a new vaccine to the public involves many steps including vaccine development, clinical trials, and U.S. Food and Drug Administration (FDA) authorization or approval.

As vaccines are distributed outside of clinical trials, monitoring systems are used to make sure that COVID-19 vaccines are safe.

None of the vaccines available can give you COVID-19. They do not affect or interact with our DNA.

  • Vaccines do not use any live virus.
  • Vaccines cannot cause infection with the virus that causes COVID-19 or other viruses.
  • These vaccines do not enter the nucleus of the cell where our DNA (genetic material) is located, so it cannot change or influence our genes.

Here are a few important facts about each of the three types of vaccines:

  • Researchers have been studying and working with mRNA vaccines, like the Pfizer and Moderna vaccines for decades. In fact, mRNA vaccines have been studied before for flu, Zika, rabies, and cytomegalovirus (CMV). Beyond vaccines, cancer research has also used mRNA to trigger the immune system to target specific cancer cells.
  • Protein subunit vaccines, like the Novavax vaccine, have been used for years. More than 30 years ago, a hepatitis B vaccine became the first protein subunit vaccine to be approved for use in people in the United States. Another example of other protein subunit vaccines used today include whooping cough vaccines.
  • For decades, hundreds of scientific studies of viral vector vaccines, like the Johnson & Johnson vaccine have been done and published around the world. Some vaccines recently used for Ebola outbreaks have used viral vector technology. Several studies have focused on viral vector vaccines against other diseases such as Zika, flu, and HIV. Besides being used in vaccines, viral vectors have also been studied for gene therapy, to treat cancer, and for molecular biology research.
How much does the vaccine cost?

The COVID-19 vaccine for all age groups, including the booster shot, is provided at no cost.

What are the possible side effects?

Side effects after getting a COVID-19 vaccine can vary from person to person. Some people experience a little discomfort and can continue to go about their day. Others have side effects that affect their ability to do daily activities.

  • Side effects generally go away in a few days.
  • Even if you don’t experience any side effects, your body is building protection against the virus that causes COVID-19.
  • Adverse events (serious health problems) are rare but can cause long-term health problems. They usually happen within six weeks of getting a vaccine.
What are the vaccine recommendations for the immunocompromised?

If you are moderately or severely immunocompromised (have a weakened immune system), you are at increased risk of severe COVID-19 illness and death. Additionally, your immune response to COVID-19 vaccination may not be as strong as in people who are not immunocompromised.

As with vaccines for other diseases, you are protected best when you stay up to date with your COVID-19 vaccines as described on the CDC website COVID-19 Vaccines for People who are Moderately or Severely Immunocompromised.

I lost my vaccination card. What can I do?

At your first vaccination appointment, you should have received a CDC COVID-19 Vaccination Record card that tells you what COVID-19 vaccine you received, the date you received it, and where you received it.

If you lost your card:

  • Contact the vaccination site where you got your first shot. Anyone who received a vaccination through University Health can access their vaccine record through their MyChart account.
  • Check your vaccine provider’s website. Retailers and pharmacies like CVS and Walgreens have vaccine information for patients on their respective websites. If you received your first or second dose at one of these retailers you can create an account online and access your COVID-19 vaccination records.
  • State health departments are also able to issue replacement vaccination cards. The Texas Department of State Health Services (DSHS) uses the Texas Immunization Registry, called ImmTrac2, to keep vaccine records.

The CDC also recommends taking a photo of your vaccination card as a backup copy.

I already had COVID-19. Do I still need to get the vaccine?

Getting a COVID-19 vaccine is a safer, more reliable way to build protection than getting sick with COVID-19. COVID-19 vaccination helps protect you by creating an antibody response without you having to experience potentially severe illness or post-COVID conditions.

Learn more about why getting vaccinated is a safer way to build protection than getting infected.



 Trust in the experience and knowledge of our experts as they answer common questions about the COVID-19 vaccine.

COVID-19 Vaccine for Adults

Dr. Mody-Bailey answers questions about the adult COVID-19 vaccine.

It seems like the vaccine was developed very quickly. Why should I trust it?

While this is the first time that a vaccine using messenger RNA (mRNA) technology (Pfizer and Moderna) has been authorized, the technology is not new! COVID-19 vaccines were developed using science that has been around for decades.

Advancements in our understanding of mRNA and its potential for use in medicines, along with the creation of new technologies over the last 30 years, made these vaccines possible. And recent research on coronaviruses made these vaccines safe and effective

If you or your loved one is still hesitant, consider the Johnson & Johnson vaccine, a viral vector vaccine. Scientists began creating viral vectors in the 1970s. Besides being used in vaccines, viral vectors have also been studied for gene therapy, to treat cancer, and for molecular biology research. For decades, hundreds of scientific studies of viral vector vaccines have been done and published around the world.

Someone I know was vaccinated, but still got COVID-19. If it’s still possible to get the virus when vaccinated, do I really need the vaccine?

Vaccine breakthroughs are expected. COVID-19 vaccines are effective and are a critical tool to bring the pandemic under control. However, no vaccines are 100% effective at preventing illness. Some fully vaccinated people will get sick, and some will even be hospitalized or die from COVID-19. However, there is evidence that vaccination may make illness less severe for those who are vaccinated and still get sick. The risk of infection, hospitalization, and death are all much lower in vaccinated compared to unvaccinated people.

Why is it important that the Pfizer vaccine has been approved by the FDA?

For months now, the Pfizer, Moderna, and Johnson & Johnson vaccine have been approved under emergency use authorization, or EUA, by the FDA. The Pfizer was the first of the vaccines to receive the EUA, and it’s also the first of the vaccines that applied for full FDA approval. Full FDA approval is a process that usually requires at least six months of safety data. Pfizer’s vaccine is now fully approved for people 16 years of age and older.

This is a huge milestone that will hopefully persuade more unvaccinated people to get their shot.

COVID-19 Vaccine for Children

Dr. Ruiz and Dr. Vacca answer questions about the COVID-19 vaccine for babies, children, and teens.

What age can my baby/child be vaccinated for COVID-19?

Centers for Disease Control and Prevention (CDC) recommends COVID-19 vaccines for everyone six months and older and boosters for everyone 5 years and older, if eligible.

When is a good time for my baby/child to receive the COVID-19 vaccine?

If your baby is six months old or older, they should be vaccinated as soon as possible.

What is the difference between the vaccine for adults and the vaccine for babies and children?

The difference is the dosage. Children get a smaller dose of COVID-19 vaccine than teens and adults that is the right amount for their age group, yet they still have a good immune response with no safety concerns.

Why did the pediatric vaccine take so long to develop?

The vaccine for children less than 5 years old has taken longer to develop because the safety and effectiveness of the vaccine was first studied in adults. Pediatric vaccine studies tested the dose and timing of the vaccines.  They carefully monitored potential side effects, medication interactions and other reactions after the patient received a vaccine.  Researchers also monitored the patient if they became ill with COVID-19 even after vaccination.

How many doses is the vaccine?

The number of doses your child receives depends on the vaccine they receive – Pfizer or Moderna. Pfizer’s trial data showed that two doses of the vaccine didn’t generate enough of an immune response, so a third vaccine was added (for ages six months through 4 years). Moderna’s vaccine requires only two doses, no matter the age.


  • Babies and children ages six months to 4 years old: 3-dose series
  • Children ages 5 to 17 years old: 2-dose series


  • Babies and children ages six months to 4 years old: 2-dose series
  • Children ages 5 to 17 years old: 2-dose series

Children and teens ages 5 through 17 years who are moderately or severely immunocompromised will need a third dose to complete their primary series, as well as boosters if eligible. Children and teens with a weakened immune system should get:

  • 1 booster if they are ages 5 through 11 years
  • 2 boosters if they are ages 12 years and older
Isn’t COVID milder in children? Does my baby/child really need this vaccine?

It is important that your baby/child receive the COVID-19 vaccine for many reasons. Like adults, babies and children can experience chronic (long-lasting) complications from COVID-19 even after they are feeling better. These can include lung infections, trouble breathing, loss of taste, multisystem inflammatory syndrome that may require intensive care, and other long-lasting symptoms.

The vaccine also:

  • Helps prevent and reduce the spread of COVID-19 to others. Getting vaccinated for COVID-19 helps protect everyone in the community, including individuals close to your child who may be more at risk of developing severe symptoms, like an immunocompromised relative or sibling, or an older caregiver, like grandma or grandpa.
  • Can stop new COVID-19 variants. Cases of COVID-19 are increasing among children, and variants of the virus appear to play a role in this. Getting vaccinated for COVID-19 reduces the virus’ chance of mutating into new variants that may be even more dangerous.
  • Restores a more normal life. Returning to school, participating in hobbies, and playing with friends are all things we want our children to experience and enjoy. Vaccinated children exposed to coronavirus are less likely to get infected, therefore, more likely to stay in school and participate in activities.
My baby/child is scheduled to get vaccines at their next checkup. Can they get a COVID-19 vaccine at the same time?

Yes. The COVID-19 vaccine can be given with or without other vaccines. This includes getting the COVID-19 vaccine and other vaccines on the same day.

Should children and teens who have previously been infected with COVID-19 get vaccinated?

Yes. Data studied over time indicate that people can get added protection by getting vaccinated after having been infected with COVID-19. So, even if a child has had COVID-19, they should still get vaccinated. For children who have been infected with COVID-19, their next dose can be delayed 3 months from when symptoms started or, if they did not have symptoms, when they received a positive test result.

Where should I get my child vaccinated?

Call your child’s doctor to make an appointment. Most Providers now have the vaccine at their offices. University Health also offers appointments for young children ages six months to just before their fifth birthday on Tuesdays and Thursdays from 7:30 a.m. to 3:30 p.m. at the Robert B. Green Campus (903 W. Martin St). Learn more and make an appointment at

COVID-19 Local Information

Visit our COVID-19 Testing & Prevention page for a list of local COVID-19 testing locations and updated quarantine guidelines from the CDC.

The San Antonio Metropolitan Health District has also opened a COVID-19 Hotline for residents to ask questions about the virus. The hotline is available in English and Spanish. Residents can call 311 or 210-207-6000 (select option 8) or visit the COVID-19 City of San Antonio webpage.

VIA is offering free transportation to or from an appointment at a city/county-sponsored COVID-19 vaccination site. Visit VIA Metropolitan Transit for more information.

COVID-19 Resources by County

Click on the county you live in for a list of area-specific COVID-19 vaccine resources.


Atascosa County uses the the Texas Public Health Vaccine Scheduler. Register online at You will be notified by email or text when and where to get the vaccine. If there’s not an available clinic near you, you will be directed to other places to get your vaccine. 

If you do not have internet, or need help scheduling an appointment, call the Texas Vaccine Support Center seven days a week from 7 a.m. to 7 p.m. at 833-832-7067. 

Additional Information:


COVID-19 Vaccine Information

Call Bandera County Emergency Management at 830-460-8299 or check with your local pharmacy or medical provider to see when vaccine appointments are available.

Additional Information:

Bandera County Emergency Management Office Facebook


Comal County COVID-19 Vaccination Plan

Comal County Public Health Department is now administering Moderna & Pfizer COVID-19 vaccines.

Call Comal County at 830-221-1150 to schedule an appointment. Please fill out the forms below and present them with your state-issued photo ID upon arrival.

Additional Information:


City of Seguin COVID-19 Vaccine Information

Click here for vaccine FAQs for Guadalupe County residents.

Guadalupe County uses the Texas Public Health Vaccine Scheduler.

  • Register online at You will be notified by email or text when and where to get the vaccine.
  • If there’s not an available clinic near you, you will be directed to other places to get your vaccine. 

If you do not have internet or need help scheduling an appointment, call the Texas Vaccine Support Center seven days a week from 7 a.m. to 7 p.m. at 833-832-7067. 

Additional Information:


The Kendall County Health Department is currently accepting appointments for COVID-19 vaccines for those who live and work in Kendall County.

If you don’t have access to the internet, please call the Health Department at (630) 553-9100. Provide your name and best phone number to reach you at and someone call you to get you registered for your COVID-19 vaccine appointment.

    Additional Information:


    Medina County Vaccine Information and Online Registration 

    Walk-ins for the COVID-19 vaccine are available at the Medina County Health Unit Monday-Thursday, 7:30 a.m.-11 a.m.and 1 p.m.-5:30 p.m.

    Click here to sign up for a vaccine appointment and to review walk-in availability with local providers in Medina County.

    Additional Information:


    i-INFO: Email Vaccine Availability Alerts for Wilson County Residents

    1. Enroll in the i-INFO system, Wilson County’s mass notification system. Click here to enroll.
    2. Upon enrollment, you will receive a notification via email when vaccine appointments become available.
    3. The email will include a link which will direct you to schedule your COVID-19 vaccine date and time. 

    If you do not have access to the internet, call the Connallly Memorial Medical Center COVID-19 Vaccine Hotline for more information at (830) 251-3105.

    Additional Information:

    We Are Here To Help

    Do you have questions about the COVID-19 vaccine or your health care benefits? Call 1-800-434-2347 Monday – Friday, 8 a.m. to 5 p.m. to speak with a representative who can help. 

    If you have questions after hours, please call the Community First Nurse Advice Line at 1-800-434-2347 available 24 hours a day, 7 days a week, 365 days a year to help you get the care you need.

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