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  • COVID-19 Vaccine FAQs

Our goal at UCR Health is to ensure that you have quick and easy access to the medical information you seek. This page provides answers to many of the most common questions raised about the COVID-19 vaccines along with links to other groups providing COVID-19 vaccine updates specific to Riverside County.

We invite you to explore all the answers provided on this page, however, FAQs have been grouped to help you quickly navigate to the answers you seek.

Lastly, stay informed and receive COVID-19 updates such as when UCR Health will be distributing vaccines to our patients by joining our newsletter HERE.


Why should I get a COVID-19 vaccine?

By receiving the COVID-19 vaccine, you will be preventing infection and death by reducing your chances of getting sick with COVID-19. 

Vaccination can also prevent the many long-lasting effects reported by COVID-19 patients, including fatigue, shortness of breath, cough, joint pain, chest pain, difficulty thinking and concentrating (“brain fog”), depression, muscle pain, headache, and intermittent fever. 

When can I get my COVID-19 vaccination?

To find out when you are eligible to receive the COVID-19 vaccination in Riverside County, please click HERE.

How long will I have immunity after I get a COVID-19 vaccine?

Those who received the Pfizer-BioNTech or Moderna COVID-19 vaccine should get a booster vaccine at least 5 months after completing their series (both doses). Those who received the Johnson & Johnson’s Janssen COVID-19 vaccine should get a booster vaccine at least 2 months after receiving their initial vaccine.

For the COVID-19 vaccines that require two doses, what happens if I miss the second dose?

For COVID-19 vaccines that are a two-dose series, both doses are required to reach full immunity. According to studies, the level of protection increases dramatically after the second dose – from 52% to 95%. It is not known whether the lower immunity from the first dose will last long.  

What if I get the first dose then don’t want the second dose?

The scientific evidence so far shows that two doses are needed to achieve 94% to 95% protection. Even though overall data suggest that benefits may start after the first dose, we don’t know enough to make any conclusions.

You should get your second dose as close to the recommended 3-week or 4-week interval as possible. However, if you receive your second dose at any time after the recommended date, you do not have to restart the vaccine series.

Therefore, you should not start the vaccine series unless you intend to complete it.  

Should I be concerned that the government was involved in creating the vaccine?

The vaccine was created by expert scientists, not the government.

The U.S. government provided money and support to assist in the production and distribution of the vaccine.  

Was the vaccine made too quickly? Should I be worried?

All COVID-19 vaccines currently distributed in the U.S. were either aided by government funds, were funded by large companies, or both.

These funds helped accelerate the trial enrollment and manufacturing process.

Each vaccine was developed and tested following the same rules as other previously approved for use medications and vaccines, such as antibiotics and the flu shot. 

What are potential long-term effects from a COVID-19 vaccine?

At the moment, we do not have long-term safety data of these COVID-19 vaccines since they have only been studied in humans for a few months. However, unexpected long-term safety issues have not been discovered in any licensed vaccines, even after decades of study. Expanded COVID-19 vaccine safety monitoring will be implemented in the U.S. as the vaccine distribution process continues. 

If I have any food or medication allergies, should I worry about having an allergic reaction to the vaccine?

The CDC recommends that people who have experienced severe allergic episodes consult their doctor before being vaccinated.

In general, people who carry epinephrine (EpiPen) should continue to do so, including at the time of vaccination.

It is also a good idea to ensure you are not alone for the first several hours after receiving the vaccine.

Should I still get the vaccine if I already had COVID-19?

Yes. One study shows that for people who have previously contracted and recovered from COVID-19 and do not get vaccinated after their recovery are over two times as likely to contract COVID-19 again compared to those who get fully-vaccinated after their recovery.

You should not receive the vaccine if you have an active COVID-19 infection. After a full recovery, you can and should receive the vaccine. 

Since vaccine supplies are limited, please wait to be vaccinated if you have had COVID-19 in the past three months. 

Can I still catch and transmit COVID-19 after I am vaccinated?

The Pfizer and Moderna clinical trials tested the vaccines’ ability to prevent symptomatic COVID-19 disease in vaccinated individuals.  

The trials did not test if vaccinated individuals could still become infected with COVID-19 or transmit the illness. 

If I get a vaccine, will I still need to follow safety protocols of masking, social distancing, etc.?

Yes. While data shows that both the Moderna and Pfizer COVID-19 vaccines are very effective, no vaccine is 100% effective. Additionally, there will be some people who choose not to be vaccinated.

Safety protocols still remain of high importance in preventing the spread of the virus. Please continue to mask, maintain social distance, and practice hand hygiene when venturing into public spaces. 

How long do I need to wait after getting a flu vaccine or another vaccine before getting a COVID-19 vaccine?

You can get a COVID-19 vaccine and other vaccines like the flu shot during the same visit. Studies have shown that the possible side effects after getting vaccinated are similar between given alone or with other vaccinations.

Can I get vaccinated while I am currently sick with COVID-19?

No. People with COVID-19 should wait to receive their vaccine until they have recovered and meet the criteria for discontinuing isolation. These guidelines apply to those who contract COVID-19 before receiving their second dose. 

Why should my child get vaccinated against COVID-19?

Children ages 5 years and older should get vaccinated against COVID-19 to prevent spreading the virus to others and better protect themselves from getting sick. Though COVID-19 tends to appear milder in children than adults, children with COVID-19 can become very sick and may require hospitalization.

Numerous of clinical trials have been performed and the results show that COVID-19 vaccines are safe and effective

To learn more, see COVID-19 Vaccines for Children and Teens


Are COVID-19 vaccines safe for children?

  • Pfizer’s COVID-19 vaccine is currently authorized for people 5 and older
  • Moderna’s and Johnson and Johnson’s COVID-19 vaccine is authorized for people 18 and older.  

Under what circumstances should someone not receive the vaccine?

You should not get the vaccine if you have had a severe allergic reaction to any ingredient in the vaccine, or if you had a severe allergic reaction to a previous dose of the COVID-19 vaccines. 

  • You can find the ingredients for the Pfizer-BioNTech COVID-19 Vaccine and additional vaccine information on the FDA website
  • You can also find the ingredients for the Moderna COVID-19 Vaccine and additional vaccine information on the FDA website

Can I get the vaccine if I am pregnant or planning to become pregnant?

Yes, you can get the COVID-19 vaccine if you are pregnant or plan to become pregnant.

However, you should consult with your OB or primary care physician to discuss the risks and benefits prior to vaccination.

Though there should be no reason to worry that getting the COVID-19 vaccine will affect your pregnancy, there will likely be some warning about getting the vaccine while pregnant since pregnant women were not included in the clinical trials.  

PLEASE NOTE: Pregnant women are at increased risk for serious disease if they become infected with COVID-19. 

The American College of Obstetricians and Gynecologists offer additional guidance on this topic. 

Can I get the vaccine if I am breastfeeding?

Yes. The COVID-19 vaccines should be offered to people who are breastfeeding. You do not need to delay or stop breastfeeding if you receive the COVID-19 vaccine. 

Lactating individuals were not part of the vaccine clinical trials.

The American College of Obstetricians and Gynecologists offer additional guidance on this topic. 


How effective are the COVID-19 vaccines?

The Pfizer and the Moderna COVID-19 vaccine trials reported a remarkable 94% to 95% efficacy in preventing COVID-19.  

The COVID-19 vaccines not only prevented COVID-19 cases overall but also prevented severe cases of the disease. 

Can I get COVID-19 from the vaccine?

No. There is no way you can get COVID-19 from the vaccine. None of the current COVID-19 vaccines in development in the United States use the live virus, SARS-CoV-2, that causes COVID-19.  

The Moderna and Pfizer COVID-19 vaccines contain a small piece of messenger RNA (mRNA) that encodes for a small portion of the viral “spike” protein. The RNA cannot replicate and does not have the components needed to infect your body. 

How do the COVID-19 vaccines work?

The COVID-19 vaccines increase the body’s immune response by making antibodies for SARS-CoV-2, the virus that causes COVID-19. The vaccines include a fragment of mRNA that encodes for a certain portion of the spike protein of the coronavirus.

When we get the vaccine, our own cells make a fragment of that protein and then our bodies build an immune response, blocking the SARS-CoV-2 virus from injecting itself into our cells and preventing it from reproducing and spreading the infection. 

How many doses do I need?

Both the Pfizer and Moderna COVID-19 vaccines require two doses. This means you must receive both doses to achieve the protection levels seen in the clinical trials. 

  • The Pfizer doses are given 21 days apart. 
  • The Moderna doses are given 28 days apart. 

When should the second dose be administered?

The second dose should be administered as close to the recommended interval as possible. However, if it is not feasible to adhere to the recommended interval, the second dose of Pfizer-BioNTech and Moderna COVID-19 vaccines may be scheduled for administration up to 6 weeks (42 days) after the first dose.

There are currently limited data on the efficacy of mRNA COVID-19 vaccines administered beyond this window. If the second dose is administered beyond these intervals, there is no need to restart the series.


What are the side effects associated with getting a COVID-19 vaccine?

Both the Pfizer and Moderna COVID-19 vaccines work to help your body produce antibodies that help fight infections from viruses and bacteria. Mild symptoms are common when the body produces antibodies and are not a sign of infection. 

Most common side effects include:  

  • Pain at the injection site 
  • Fatigue 
  • Headache 
  • Muscle pain 
  • Chills 
  • Joint pain 
  • Mild fever 

Like any vaccine, there is a low chance of an allergic reaction occurring. Please talk with your doctor about receiving a COVID-19 vaccine if you have a history of severe allergic reactions to other vaccinations.  

Is the COVID-19 going to alter my DNA?

No. The COVID-19 vaccine contains a small portion of mRNA that is short-lived and only works in one direction, meaning that the RNA does not interact with or alter your DNA and never enters the part of the cell where DNA is located. 

Is the mRNA vaccine technology new? Should I be worried about it?

The messenger mRNA (mRNA) vaccine technology used in the Pfizer and Moderna vaccines is new, but not unknown. It is the first time mRNA has been used in a licensed vaccine, however, the structure and technology have been studied for years.

Through advancements in science, mRNA vaccines are thought to be less dangerous than other types of vaccines.  


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