Frequently Asked Questions about COVID-19 Vaccines

We understand you may have many questions about COVID-19 vaccines. Valley Children’s has developed this list of frequently asked questions as a resource to keep you informed and help answer questions you may have about this quickly evolving topic.

Valley Children’s Hospital is not currently providing drive-through COVID-19 vaccination to the general public. Google is incorrectly listing Valley Children’s as a drive-through COVID-19 vaccine site. We apologize for any confusion this may be causing our community. You can find out more about scheduling a COVID-19 vaccine at


Pfizer and Moderna vaccines have proven safe after millions of doses given in the U.S. and worldwide. There is a concern about a potential serious health problem after the Johnson & Johnson vaccine. The CDC and FDA have recommended that this vaccine not be given until further investigation is completed regarding the health problem (clotting problems).

Common side effects are temporary and can include: fever, chills, tiredness, headache and pain or swelling in the arm you got the vaccine.

Pfizer Vaccine

  • Uses mRNA technology
  • Two doses, 3-6 weeks apart
  • FDA authorized for persons 16 and older

Moderna Vaccine

  • Uses mRNA technology
  • Two doses, 4-6 weeks apart
  • FDA authorized for persons 18 and older

Johnson & Johnson Vaccine (also called Janssen Vaccine)

  • Ad26 (adenovirus vector, replication incompetent) vaccine
  • One dose
  • FDA authorized for persons 18 and older

All three vaccines are safe, effective and have been proven to prevent severe illness that would require hospitalization, including intensive care and death.

Moderna and Pfizer vaccines use mRNA technology. You might think about mRNA vaccines as being like an email that sends instructions to your body about how to fight off an infection. When you get an mRNA vaccine for COVID-19, your body reads the instructions about what to do if it encounters the virus that causes COVID-19. Once your body learns these instructions, it deletes the email.

It is important to understand that mRNA vaccines do not change or interact with the DNA in our bodies in any way because mRNA never enters the nucleus of the cell, which is where our DNA is kept. The cell breaks down and gets rid of the mRNA soon after it is finished using the instructions.

The Johnson & Johnson vaccine is an adenovirus (or viral) vector vaccine. The viral vector vaccine carries a gene from the coronavirus into human cells, which then produces the coronavirus spike protein, but not the coronavirus itself. This spike protein is what causes the immune system to fight off the infection. The adenoviral vector cannot replicate, so you cannot get an infection from this vaccine.

  • People who have a known history of a severe allergic reaction to any component of the vaccine
  • The Moderna and Johnson & Johnson vaccines are not available to persons under 18 years of age
  • The Pfizer vaccine is not available to children under age 16
  • People who have had another vaccine within 14 days (within 28 days of live viral vaccine for the Johnson & Johnson vaccine)
  • People who have fever on the day of the vaccine
  • People who are on quarantine or isolation for COVID exposure or disease
  • People who have been treated with convalescent plasma or monoclonal antibody therapy for COVID-19 within the last 90 days

The Food and Drug Administration (FDA) has authorized two vaccines for people 18 and older and one vaccine for people 16 and older. The Centers for Disease Control and Prevention (CDC) recommends that everyone eligible to receive the vaccine get it, especially adults of any age with certain underlying medical conditions because they are at an increased risk for severe illness form the virus that causes COVID-19.

People can receive the COVID-19 vaccines if they have not had an immediate or severe allergic reaction to any of the ingredients in the vaccine. More information about COVID-19 vaccines and allergic reactions is available on the CDC’s website. Ask your healthcare provider if you have any questions about your health history and the vaccine.

No. You will not get COVID-19 from receiving the COVID-19 vaccine because there is no live virus in the COVID-19 vaccines.

As long as you have recovered from your acute COVID-19 illness and are no longer contagious, you are encouraged to get the vaccine because of the risk of reinfection. We do not know how long antibodies last after infection. You may choose to wait up to 90 days after your infection before receiving a vaccine, as natural protection from infection is thought to last at least that long.

The CDC recommends 14 days between receiving a COVID-19 and non-COVID-19 vaccine, regardless of their received order.

Currently, there is limited data available on the safety of COVID-19 vaccines administered during pregnancy. Early COVID-19 vaccine studies did not include pregnant women. Still, some participants were either pregnant and did not know it or became pregnant during the course of the study. In this small group, there were no safety concerns found, and the vaccine was effective. Since the vaccine has become available, 30,000 pregnant women in the United States have received the vaccine with no safety signals found.

The adenovirus platform used by the Johnson & Johnson vaccine has been used previously in pregnant women and was found to be safe.  

According to the Centers for Disease Control and Prevention (CDC) and the American College of Obstetricians and Gynecologists (ACOG), women who are trying to conceive, pregnant or breastfeeding should not be excluded from receiving the COVID-19 mRNA vaccines if they choose to do so. We encourage women to partner with their healthcare provider to make a shared decision after being provided with information about the potential risks and benefits of COVID-19 vaccines.

It is important to note that some pregnant women may be at higher risk for COVID-19 and pregnant women are at an increased risk for developing complications, compared to non-pregnant women, when ill with COVID-19.

For more information about COVID-19 vaccines and pregnancy, visit the CDC’s website.

Women do not need to delay breastfeeding for any amount of time after receiving the COVID-19 vaccine. We do suggest that all women who are breastfeeding practice proper hand hygiene.

The baby may also benefit from antibodies passed through breast milk after the mother is vaccinated.

People who are trying to conceive:
People who are trying to conceive can get the COVID-19 vaccine. According to the American Society of Reproductive Medicine (ASRM), American College of Obstetricians (ACOG) and the Society of Maternal-Fetal Medicine (SMFM), there is no evidence that the vaccine can lead to loss of fertility in women or men.

Everyone is recommended to still follow safety measures after getting the COVID-19 vaccine because it will still take some time to slow the spread of COVID-19 and to get our communities vaccinated.

While the COVID-19 vaccines appear to be highly effective at preventing infection, it is not yet known if they are effective in preventing asymptomatic infections (someone who has COVID-19 with no symptoms) who can then pass to another person.

For this reason, we need to work together to slow and stop the spread of the virus. We encourage everyone to keep wearing a facial mask, practicing proper hand hygiene and to socially distance.