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COVID-19 Vaccine FAQ

get the facts and get vaccinated


Updated May 13, 2021

Why are vaccines important?

It is always better to prevent a disease than to treat it after it occurs.

  • Over the years, vaccines have prevented countless cases of disease and saved millions of lives. Diseases that used to be common in this country and around the world, including polio, measles, diphtheria, pertussis (whooping cough), rubella (German measles), mumps, tetanus, rotavirus and Haemophilus influenzae type b (Hib) can now be prevented by vaccination.  

  • Getting a vaccine also benefits your loved ones and people in your community by creating “herd immunity.” If enough people are vaccinated, the disease cannot spread as quickly.  

  • Stopping a pandemic requires all the tools we have available.

Vaccines and Immunizations | CDC

What is the COVID-19 vaccine and what does it do?

The COVID-19 vaccine is provided to a person to give them protection from the coronavirus. COVID-19 vaccination helps protect you by creating an antibody response without having to experience sickness. Sometimes after vaccination, the process of building immunity can cause symptoms, such as soreness where you received the injection or fatigue. These symptoms are normal and are a sign that the body is building immunity.

Understanding How COVID-19 Vaccines Work | CDC

What are the different types of COVID-19 vaccines?

­Multiple vaccines to protect people from COVID-19 are in specific phases of development or approval.  The chart below summarizes key facts for three companies that are developing the vaccines: Pfizer, Moderna, and Johnson & Johnson.

EUA: 12/11/20
EUA: 12/18/20
Johnson & Johnson
EUA: 2/26/21
Vaccine Mechanism of Action (TYPE)mRNA mRNA Vector

95% effective

94.5% effective66.9% effective **
# Participants43,000 in phase-3 trial30,000 in phase-3 trial40,000
Level of Diversity42% diverse backgrounds37% diverse backgrounds37.9% diverse backgrounds
Storage Temperature and
Shelf Life
Ultra-cold storage (-75 degrees Celsius, -103 degrees Fahrenheit).
Lasts up to 5 days in refrigeration.
Storage temperature at -20 degrees C (-4 degrees F).
Lasts up to 30 days in refrigeration.
Regular refrigeration (36-46 degrees F).
Lasts up to 3 months in refrigeration.
Dosing Schedule2-dose schedule:
21 days apart
2-dose schedule:
28 days apart
Single dose

1. COVID Vaccine | NC DHHS
2. Moderna Provides Updates on the Clinical Development and Production of Its COVID-19 Vaccine Candidate | Moderna, Inc.
3. Pfizer and BioNTech Conclude Phase 3 Study of COVID-19 Vaccine Candidate, Meeting All Primary Efficacy Endpoints | Pfizer
4. AZD1222 vaccine met primary efficacy endpoint in preventing COVID-19 | Astrazeneca
5. Vaccines and Related Biological Products Advisory Committee February 26, 2021 Meeting Briefing Document- Sponsor | FDA

How do mRNA vaccines (Pfizer and Moderna) work?

  • mRNA vaccines teach our cells how to make a harmless piece of the "spike protein" for SARS-CoV-2.
    • After the protein piece is made, the cell breaks down the instructions (the mRNA) and gets rid of them.
  • Cells display this piece of spike protein on their surface, and an immune response is triggered inside our bodies. This produces antibodies to protect us from getting infected if the SARS-CoV-2 virus enters our bodies.
  • mRNA vaccines do not use the live virus that causes COVID-19. They CANNOT give someone COVID-19.
  • mRNA vaccines DO NOT affect or interact with our DNA in any way.

COVID-19 Vaccine Communications Toolkit | CDC

How do vector vaccines, such as Johnson & Johnson's, work?

This vaccine mechanism is used by the Johnson and Johnson vaccine and the AstraZeneca vaccine (still undergoing clinical trials process).

  • Viral vector vaccines use a modified version of a different virus (the vector) that is harmless to humans to deliver important instructions to our cells. For COVID-19 viral vector vaccines, the vector (not the virus that causes COVID-19, but a different, harmless virus) will enter a cell in our body and then instruct the cell’s machinery to produce a harmless piece of the virus that causes COVID-19. This piece is known as a spike protein and it is only found on the surface of the virus that causes COVID-19.
  • After the viral vector delivers the instructions to create the spike protein, it is broken-down and disposed of.
  • The cell then displays the spike protein on its surface, and our immune system recognizes it doesn’t belong there. This triggers our immune system to begin producing antibodies and activating other immune cells to fight off what it thinks is an infection.
  • Viral vectors cannot cause infection with COVID-19 or with the virus used as the vaccine vector.
  • The genetic material delivered by the viral vector does NOT interact with or change a person’s DNA in any way.

Understanding Viral Vector COVID-19 Vaccines | CDC

For the Pfizer and Moderna vaccines, the second dose is identical to the first dose.

Do I need multiple doses of the COVID-19 vaccine?

The Pfizer and Moderna vaccines each require a second dose 21-28 days after the first shot. Johnson & Johnson is the only vaccination that requires a single dose.

Pfizer: 21 days
Moderna: 28 days
Johnson and Johnson: 1 dose

ACIP COVID-19 Vaccine

What is the difference between the first and second dose of the Pfizer and Moderna vaccines?

  • For the Pfizer and Moderna vaccines, the second dose is identical to the first dose.
  • The initial shot is intended to prime your immune system. The second dose acts as a booster shot and stimulates an optimal antibody response.
  • In the clinical trials, the efficacy of both vaccinations increased substantially when a second dose was administered, creating a much higher level of protection.
  • Some people may have stronger side effects after their second dose. This is a sign that the vaccine is working. Your body now recognizes the harmless spike protein that is exhibited on the coronavirus and has triggered an appropriate immune response. 

What are the side effects of the vaccine?

Some people may have temporary reactions after being vaccinated, such as some pain and swelling at the injection site, tiredness or feeling off for a day or two.

These mRNA vaccines are expected to produce side effects after vaccination, especially after the 2nd dose.

Side effects may include: 

  • Soreness at the injection site
  • Fatigue
  • Fever
  • Headache
  • Muscle aches

No significant safety concerns were identified in the clinical trials. At least 8 weeks of safety data were gathered in the trials. It is unusual for side effects to appear more than 8 weeks after vaccination.

1. COVID-19 Vaccines | NC DHHS
2. Pfizer Vaccination EUA Fact Sheet for Recipients
3. What Clinicians Should Know | CDC
4. Johnson & Johnson FDA Briefing

How do I know the vaccine is safe?

Scientists had a head start. Although the vaccines were developed quickly, they were built upon years of work in developing vaccines for similar viruses.

Testing was thorough and successful. More than 70,000 people participated in clinical trials for two vaccines to see if they are safe and effective. To date, the vaccines are nearly 95% effective in preventing COVID-19 with no safety concerns.

There are no safety concerns for senior citizens. Clinical trials ensured the vaccines meet safety standards and protect adults of different races, ethnicities, and ages, including adults over the age of 65, who mounted a strong immune response.

There is no COVID-19 virus in the vaccine. The vaccine imitates the infection so that our bodies think a germ like the virus is attacking. This creates the antibody defenses we need to fight off COVID-19 if and when the real germ attacks.

Ensuring vaccine safety in the United States: FDA | CDC

NC Vaccine Approval Infographic. Phase 1 and 2: 10s-100s of healthy volunteers. Are there any side effects? How many volunteers experience side effects? What is the best vaccine dose to create an immune response with the fewest tolerable side effects? Phase 2 and 3: More than 30,000 of volunteers. Does the vaccine prevent COVID-19 infection? What are the most common side effects? Do the benefits of the vaccine outweigh the risks? APPROVAL and DISTRIBUTION: FDA reviews the safety and efficacy data to determine if benefits are greater than risks. An independent, non-FDA scientific committee reviews findings. Vaccine is authorized and recommended for use (may only be for certain populations). Vaccine is labeled for use, benefits, side effects. Manufacturing Preparation: Manufacturing development scaling up, quality-control testing. Large-Scale Manufacturing: Making millions of vaccine doses for nationwide distribution, continued quality-control testing of vaccine batches and manufacturing facilities, FDA ad CDC continually monitor vaccinated patients. Availability: Limited availability in the beginning. More widely available over time.

What are the benefits of getting a COVID-19 vaccine?

  • The vaccine will help protect you from getting COVID-19.
  • COVID-19 can have serious, life-threatening complications, and there is no way to know how COVID-19 will affect you.
  • If you get sick, you could spread the disease to friends, family, and others around you.
  • Getting the vaccine, in addition to wearing a mask, social distancing, and washing hands, is an important tool to stop the pandemic.

Benefits of Getting a COVID-19 Vaccine | CDC

How long will I be protected from COVID-19 after getting the vaccine?

Unfortunately, we won’t know how long immunity lasts until we have a vaccine that is released and observed long-term. We will continue to update our information as new data is released.

COVID-19 Vaccination FAQ | CDC

Should I get the vaccine if I currently have COVID-19 or have recovered from COVID-19?

If you currently have COVID-19:  

  • Vaccination should be delayed until they recover from acute illness (if person had symptoms) and criteria have been met to discontinue isolation (as instructed by their healthcare provider or their local health department).

If you've recovered from COVID-19: 

  • You should be vaccinated. That’s because experts do not yet know how long you are protected from getting sick again after recovering from COVID-19. Even if you have already recovered from COVID-19, it is possible—although rare—that you could be infected with the virus that causes COVID-19 again. If you were treated for COVID-19 with monoclonal antibodies or convalescent plasma, you should wait 90 days before getting a COVID-19 vaccine. Talk to your doctor if you are unsure what treatments you received or if you have more questions about getting a COVID-19 vaccine.

Mrna Vaccine Clinical Considerations | CDC

If I get the COVID-19 vaccine, do I still need to wear a face mask and socially distance?

Stopping a pandemic requires using all the tools available. Vaccines work with your immune system so your body will be ready to fight the virus if you are exposed.

Other steps, like covering your mouth and nose with a mask and staying at least 6 feet away from others, help reduce your chance of being exposed to the virus or spreading it to others. Together, COVID-19 vaccination and following CDC's recommendations to protect yourself and others will offer the best protection from COVID-19.

  • Wear a mask when you are in public places or not able to social distance.
  • Avoid close contact with people who are sick.
  • If you are sick, limit contact with others as much as possible to avoid infecting them.
  • Cover coughs and sneezes.
  • Wash your hands often with soap and water. If soap and water are not available, use an alcohol-based hand rub.
  • Avoid touching your eyes, nose and mouth.
  • Clean and disinfect surfaces and objects that may be contaminated with viruses.

    FAQ COVID-19 Vaccination | CDC



If I receive the COVID-19 vaccine and come into contact with someone that has COVID-19, do I still need to quarantine?

Vaccinated persons with an exposure to someone with suspected or confirmed COVID-19 are NOT required to quarantine if they meet all of the following criteria: 

  • Are fully vaccinated (i.e., ≥2 weeks following receipt of the second dose in a 2-dose series, or ≥2 weeks following receipt of one dose of a single-dose vaccine).
  • Have remained asymptomatic since the current COVID-19 exposure.

Fully vaccinated people who do not quarantine should still monitor for symptoms of COVID-19 for 14 days following an exposure. If they experience any symptoms, they should:

  • Isolate themselves from others.
  • Be clinically evaluated for COVID-19, including SARS-CoV-2 testing, if indicated by their healthcare provider.
  • Inform their healthcare provider of their vaccination status at the time that they receive care.

Interim Clinical Considerations for Use of mRNA COVID-19 Vaccines | CDC

Who should NOT get a COVID-19 vaccine?

Severe allergic reaction (e.g., anaphylaxis) to any component of the specific vaccine the individual is receiving (Pfizer-BioNTech or Moderna COVID-19 vaccine) is a contraindication to vaccination

A severe allergic reaction to any vaccine or injectable therapy is a precaution to vaccination at this time.

    • Vaccine providers should observe patients after vaccination to monitor for the occurrence of immediate adverse reactions

Children ages 11 and under should not receive the Pfizer vaccine at this time. Individuals ages 17 and under should not receive the Moderna vaccine at this time.

More information to come as additional vaccines are approved.

Pfizer-BioNTech COVID-19 Vaccine EUA Fact Sheet for Recipiets and Caregivers | FDA
Moderna COVID-19 Vaccine EUA Fact Sheet for Healthcare Providers | FDA

If I have allergies, can I still get the COVID-19 vaccine?

Most people with allergies can still get the COVID-19 vaccine.

The Centers for Disease Control (CDC) has issued guidelines that people who have ever had a severe allergic reaction, known as anaphylaxis, to any ingredient in a COVID-19 vaccine should not get it, and to consult their doctor about getting the vaccine. This includes allergic reactions to PEG and polysorbate, which are closely related to each other. PEG is an ingredient in the mRNA vaccines, and polysorbate is an ingredient in the J&J/Janssen vaccine.

If you are allergic to PEG, you should not get an mRNA COVID-19 vaccine. Ask your doctor if you can get the J&J/Janssen vaccine.

If you are allergic to polysorbate, you should not get the J&J/Janssen COVID-19 vaccine. Ask your doctor if you can get an mRNA COVID-19 vaccine.

Individuals with severe allergic reaction (e.g. anaphylaxis) to another vaccine or injectable medication may wish to consult with their medical provider; this is not an absolute contraindication to get the vaccine. In other words, most people with allergies can still get the vaccine.

COVID-19 Vaccines and Severe Allergic Reactions | CDC

Is the vaccine effective against the new strains and varients of COVID-19?

Information about the characteristics of SARS-CoV-2 (the virus that causes the COVID-19 disease) variants is rapidly emerging. Scientists are working to learn more about how easily these variants may spread, whether they could cause more severe illness, and whether currently authorized vaccines will protect people against them.

Viruses constantly change through mutation, and new variants of a virus are expected to occur over time. Sometimes new variants emerge and disappear. Other times, new variants emerge and persist. Multiple variants of the virus that causes COVID-19 have been documented globally during this pandemic. The variants are given letter and number combinations that indicate their genetic lineage and differences in the physical characteristics of the virus. They are more commonly named after the countries in which they were first discovered in. 

  • B.1.1.7 - “The U.K Variant”
  • B.1.351 - “The South African Variant” 
  • P.1 - “The Brazilian Variant”

These three variants, described by the U.S Centers for Disease Control and Prevention (CDC) as “variants of concern,” have spread globally and have all been reported in the US. Currently, there are fewer than 100 cases belonging to these variants in North Carolina.

These variants seem to spread more easily and quickly than other variants, which may lead to more cases of COVID-19. An increase in the number of cases will put more strain on health care resources, lead to more hospitalizations, and potentially more deaths. 

So far, studies suggest that antibodies generated through vaccination for COVID-19 recognize these variants and are effective against them. This is being closely investigated and more studies are underway.

Where can I go for more information?

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