COVID-19 Vaccine FAQ

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How is the flu vaccine different from the mRNA COVID-19 vaccines?

“The most common way that flu vaccines are made is using an egg-based manufacturing process that has been used for more than 70 years. Egg-based vaccine manufacturing is used to make both inactivated (killed) vaccine (usually called the “flu shot”) and live attenuated (weakened) vaccine (usually called the “nasal spray flu vaccine”).”(1, CDC)

“Vaccines do not need to have high effectiveness to save thousands of lives and prevent millions of disease cases. The popular flu shot, for example, has an effectiveness of 40­–60%, according to the Centers for Disease Control and Prevention (CDC). [L]ooking at…vaccines that we have previously reported on, Pfizer/BioNTech boasts 95% efficacy…while the Moderna vaccine candidate reportedly has 94.1% efficacy.” (2, MNT)

“Moderna and Pfizer-BioNTech use what’s called messenger RNA, or mRNA, to give our cells the genetic instructions. The J&J vaccine instead uses a harmless adenovirus to deliver the instructions to our cells to produce the spike protein found on the surface of the coronavirus. In each case, when our cells recognize the spike protein, they can create antibodies to block it from infecting our bodies.” (10, AARP)

Is there live virus in COVID-19 vaccine?

No. Gretchen Moen, DNP, APRN, CPNP  and Clinical Director at Dakota Child and Family Clinic says “mRNA is the code for the spike protein from SARS-CoV-2 which causes COVID-19 but is not a viral particle.”

“The Johnson & Johnson vaccine is based on the virus’s genetic instructions for building the spike protein. But unlike the Pfizer-BioNTech and Moderna vaccines, which store the instructions in single-stranded RNA, the Johnson & Johnson vaccine uses double-stranded DNA. The researchers added the gene for the coronavirus spike protein to another virus called Adenovirus 26. Adenoviruses are common viruses that typically cause colds or flu-like symptoms. The Johnson & Johnson team used a modified adenovirus that can enter cells but can’t replicate inside them or cause illness.” (11, NYT)

“The mRNA vaccines include:

  • mRNA – This mRNA is for the spike protein of SARS-CoV-2, the virus that causes COVID-19.
  • Lipids – These are molecules that are not able to dissolve in water. They protect the mRNA, so that it does not break down before it gets into our cells. These can be thought of as little “bubbles of fat,” which surround the mRNA like a protective wall. There are four different lipids in the Pfizer vaccine and three in the Moderna vaccine. One of the lipids in both vaccines is cholesterol. The lipids are the most likely components of the vaccine to cause allergic reactions.
  • Salts and amines – The Pfizer vaccine contains four salts. One is table salt. The salts are used to keep the pH of the vaccine similar to that found in the body, so that the vaccine does not damage cells when it is administered. The Moderna vaccine also contains four chemicals to balance the pH, but two are in a class of organic compounds known as “amines” and two are acetic acid and its salt form, sodium acetate. Acetic acid is the main component of vinegar (other than water).
  • Sugar – This ingredient is literally the same as that which you put in your coffee or on your cereal. It is used in both of  the vaccines to help keep the “bubbles of fat” from sticking to each other or to the sides of the vaccine vial.” (3, Children’s Hospital of Philadelphia)

Do I have to wear a mask after being vaccinated?

“Yes. While experts learn more about the protection that COVID-19 vaccines provide under real-life conditions, it will be important for everyone to continue using all the tools available to us to help stop this pandemic, like covering your mouth and nose with a mask, washing hands often, and staying at least 6 feet away from others. Together, COVID-19 vaccination and following CDC’s recommendations for how to protect yourself and others will offer the best protection from getting and spreading COVID-19. Experts need to understand more about the protection that COVID-19 vaccines provide before deciding to change recommendations on steps everyone should take to slow the spread of the virus that causes COVID-19. Other factors, including how many people get vaccinated and how the virus is spreading in communities, will also affect this decision.” (4, CDC)

What is the difference between the vaccines being offered why are there three different protocols?

“Both vaccines (Pfizer and Moderna) are made using a newer technology called messenger RNA (mRNA). An mRNA vaccine works by encoding a portion of the spike protein found on the surface of SARS-CoV-2, the virus that causes COVID-19, the Centers for Disease Control and Prevention (CDC) explains.” The Pfizer and Moderna vaccine have similar side effects; muscle pain, injection site pain, fever, etc. “The Pfizer vaccine has to be shipped in specially-designed, temperature-controlled thermal shippers that keep conditions around -70 degrees Celsius (-94 degrees Fahrenheit), per a Pfizer fact sheet. The vaccine can be stored in those conditions for up to 10 days. From there, it needs to be stored in “ultra-low temperature freezers” for up to six months. The Pfizer vaccine can also be stored in refrigeration units that are “commonly available in hospitals” at temperatures between 36 to 46 degrees Fahrenheit for five days, Pfizer says. The Moderna vaccine is a little different. It should be shipped at -20 degrees Celsius (-4 degrees Fahrenheit) and can stay stable in refrigeration units between 2 to 8 degrees Celsius (36 to 46 degrees Fahrenheit) for 30 days, the company says online. The vaccine will stay stable at -20 degrees Celsius for up to six months and at room temperature for up to 12 hours.(5, Health)

“The most basic difference is that the Johnson & Johnson vaccine is an adenovirus vector vaccine, while the Moderna and Pfizer vaccines are both mRNA vaccines. Messenger RNA vaccines use genetic instructions from the coronavirus to tell a person’s cells to make the spike protein, but these don’t use another virus as a vector. There are many practical differences, too.Both of the mRNA-based vaccines require two shots. The Johnson & Johnson vaccine requires only a single dose. This is key when vaccines are in short supply. The Johnson & Johnson vaccine can also be stored at much warmer temperatures than the mRNA vaccines. The mRNA vaccines must be shipped and stored at below–freezing or subzero temperatures and require a complicated cold chain to safely distribute them. The Johnson & Johnson vaccine can be stored for at least three months in a regular refrigerator, making it much easier to use and distribute. As for efficacy, it is difficult to directly compare the Johnson & Johnson vaccine with the mRNA vaccines due to differences in how the clinical trials were designed. While the Moderna and Pfizer vaccines are reported to be approximately 95% effective at preventing illness from COVID–19, the trials were done over the summer and fall of 2020, before newer more contagious variants were circulating widely. The Moderna and Pfizer vaccines might not be as effective against the new variants, and Johnson & Johnson trials were done more recently and take into account the vaccine’s efficacy against these new variants.” (12, PBS)

What are the side effects of each of the vaccines available?

Fact Sheet Pfizer

Fact Sheet Moderna

Fact Sheet Johnson & Johnson (Janssen)

“J&J’s trial did not reveal any significant safety concerns, with only 9 percent of those participating in the clinical trials reporting a fever. There were no cases of a severe allergic reaction to the shot.” (10, AARP)

“The most common adverse reactions among more than 6,000 study participants who were queried about their experience were injection site pain (49%), headache (39%), fatigue (38%) and muscle pain (33%). These side effects were mostly mild or moderate.” (13, NPR)

Does the COVID-19 vaccine make you sick with COVID-19?

“No. None of the COVID-19 vaccines contain the live virus that causes COVID-19 so a COVID-19 vaccine cannot make you sick with COVID-19. Facts about COVID-19 Vaccines ” (6, CDC)

“To create this vaccine, the Johnson & Johnson team took a harmless adenovirus – the viral vector – and replaced a small piece of its genetic instructions with coronavirus genes for the SARS-CoV-2 spike protein. After this modified adenovirus is injected into someone’s arm, it enters the person’s cells. The cells then read the genetic instructions needed to make the spike protein and the vaccinated cells make and present the spike protein on their own surface. The person’s immune system then notices these foreign proteins and makes antibodies against them that will protect the person if they are ever exposed to SARS-CoV-2 in the future.The adenovirus vector vaccine is safe because the adenovirus can’t replicate in human cells or cause disease, and the SARS-CoV-2 spike protein can’t cause COVID–19 without the rest of the coronavirus. This approach is not new. Johnson & Johnson used a similar method to make its Ebola vaccine” (12, PBS)

“The vaccines may cause side effects. According to the FDA, the most common side effects among participants in both the Pfizer-BioNTech and Moderna phase 3 clinical trials were:

  • Injection site pain
  • Fatigue
  • Headache
  • Muscle pain
  • Chills
  • Joint pain
  • Fever
However, these reactions are “temporary,” and they “self-resolve” within a few days, says Wilbur Chen, M.D., a professor of medicine and chief of adult clinical studies at the Center for Vaccine Development and Global Health at the University of Maryland.” (7, AARP)

How long does it take to build immunity?

“It typically takes a few weeks for the body to build immunity after vaccination. That means it is possible a person could be infected with the virus that causes COVID-19 just before or just after vaccination and get sick. This is because the vaccine has not had enough time to provide protection.” (8, UAB)

“The 95% efficacy number for the Covid-19 vaccines also assumes some built-in wait time. Moderna measured the efficacy of its vaccine starting 14 days after the second dose, while Pfizer measured it starting seven days after the second dose.” CNNwire (9, ABC7)

For Johnson & Johnson, only one shot is required. “In the large clinical trial that is the centerpiece of the company’s application to the FDA, nobody who received the vaccine required hospitalization or died once the vaccine took full effect (28 days after immunization.)” (13, NPR)

I don’t trust this vaccine.

We hear you. Our task is to give you the tools to make the right decision for you. Check out these articles and do your own research.

Trustworthiness before Trust — Covid-19 Vaccine Trials and the Black Community

Opportunities for Advancing Health Justice in the COVID-19 Era

Many Black Americans don’t trust the covid-19 vaccine; here’s why and what’s being done

COVID-19 vaccine myths debunked-Mayo Clinic

The real facts about common COVID-19 vaccine myths – UC Davis Health

Why You Should Still Wear A Mask And Avoid Crowds After Getting The COVID-19 Vaccine – NPR

Where can I find a vaccination site?

Minnesota Vaccine Rollout

Making the Covid 19 Vaccine-PBS

Talking With People In Your Life Hesitant About The Coronavirus Vaccine-NPR

How the Johnson & Johnson Vaccine Works


  1. CDC. (2020, September 10) How Influenza (Flu) Vaccines Are Made.
  2. Sandoiu, A. (2020, December 14). How do COVID-19 vaccines compare with other existing vaccines? Medical News Today.
  3. Children’s Hospital of Philadelphia. (2020, December 22). Questions and Answers about COVID-19 Vaccines.
  4. CDC. (2020, December 29). Frequently Asked Questions about COVID-19 Vaccination.
  5. Miller,K. (2020, December 18).What Are the Differences Between the Pfizer and Moderna COVID-19 Vaccines? Here’s What We Know So Far. Health.
  6. (2021, January 5) Benefits of Getting the COVID-19 Vaccine. CDC.
  7. Nania.R (2020, December 21). What are the side effects of the COVID-19 Vaccine? AARP.
  8. Pope. A. (2020, December 15). What you need to know about the Pfizer COVID-19 vaccine. University of Alabama-Birmingham.
  9. (2021, January 11). How much protection does the COVID-19 vaccine offer? How vaccinated people should approach seeing others. COVID-19Vaccine.
  10. Bunis, D. (2021, February 4). Single-Dose J&J Vaccine Is 66 Percent Effective in Clinical Trials. AARP.
  11. Corum, J. & Zimmer, C. (2021, February 27). How the Johnson & Johnson Vaccine Works. The New York Times.
  12. (2021, March 1). How does the Johnson & Johnson vaccine compare to other coronavirus vaccines? PBS.
  13. Hensley, S. (2021, February 24) FDA Analysis of Johnson & Johnson COVID-19 Vaccine Finds it Safe, Effective. NPR.