COVID-19 VACCINE FAQ
causes them to become activated and
respond. The result is the production of
neutralizing antibodies. If a person who
is immunized becomes infected with the
virus, the neutralizing antibodies will bind
to the virus and prevent it from entering
cells and causing disease.
Can the vaccines cause COVID-19?
No. An mRNA vaccine is not a virus and
can’t cause disease. Because it activates
the immune system, it can cause mild
symptoms in some people (e.g., fatigue,
achiness, fever). Based on data from
the clinical trials, the most common
reactions to the vaccine are pain at the
injection site, fatigue, headache, and
muscle aches. These symptoms are very
common with other vaccines, including
the flu shot, and are a sign that the body
is responding to the vaccine.
The other authorized vaccine uses a
modified virus that can’t replicate and does
not cause any disease, including COVID-19.
How do COVID-19 vaccines work?
Two COVID-19 vaccines use
messenger RNA (mRNA), which is a
set of instructions that tells a cell to
make a specific protein. For SARS-
CoV-2 (COVID-19), this is the spike
protein that is found on the surface of
the viral envelope. The mRNA used
in the vaccines don’t enter the cell’s
nucleus and has no interaction with a
cell’s DNA. It is also not a full virus and
cannot replicate itself. The mRNA is
rapidly broken down by the cell once
the instructions have been transmitted,
so it does not cause mutations or
cellular defects, and has not been
associated with infertility.
The other vaccine uses a modified
adenovirus that contains DNA for the
spike protein. The adenovirus is able
to enter a cell and cause the spike
protein to be made. Adenoviruses are
a source of the common cold, but this
particular virus can’t replicate so it
won’t cause disease.
Once the spike protein is made, it is
put on the surface of the cell, where
it is seen by the immune cells and
COVID-19 VACCINE FAQ, CONTINUED
When will a vaccine be available?
The FDA has authorized three vaccines for COVID-19. The Pfizer-BioNTech mRNA vaccine was
authorized for individuals 16 years and older. The Moderna mRNA vaccine and Janssen (Johnson &
Johnson) adenovirus vaccine were authorized for individuals 18 years and older. All three vaccines were
recommended by the CDC’s Advisory Committee on Immunization Practices (ACIP). They will review
additional vaccines when authorized by the FDA.
The first groups of people, health care workers and residents of long-term-care facilities, began
receiving vaccine doses in late December. Additional allocation phases included front-line essential
workers, individuals over 75 years of age, and those at increased risk of severe disease. Local health
departments can provide information on how remaining groups can get the vaccine.
5 THINGS YOU NEED TO KNOW NOW (as of April 16, 2021)
1.
The CDC and FDA recommended a pause in use of the single dose
Johnson & Johnson vaccine. This is related to six cases of a rare blood clot
associated with low platelet counts. The pause will continue until the CDC’s
ACIP has time to analyze data and determine if the recommendation
should change.
2. There has been no link between the mRNA vaccines and the blood clot
and low platelet counts seen with the Johnson & Johnson vaccine.
3. Follow vaccine schedules as recommended by the CDC. Pfizer-BioNTech
and Moderna require two doses 3–4 weeks apart. Mild pain at the injection
site, fatigue, headache, and muscle aches are common reactions.
4. The vaccines do not cause COVID-19.
5. Vaccines provide protection against COVID-19, but won’t prevent infection.
It’s important to continue wearing a mask, wash hands and physically
distance even after getting fully vaccinated.
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COVID-19 VACCINE FAQ, CONTINUED
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What is the difference between the emergency use authorization and
licensure (approval) by the FDA?
Emergency use authorization (EUA) is a process by which the FDA can authorize use of a
medication or vaccine with less data if the benefit of the vaccine has been shown to outweigh
the risk. EUAs can be issued only during a declared emergency, such as the COVID-19
pandemic. Vaccines issued an EUA will continue to be studied and have additional safety
monitoring and informed consent and education associated with them.
What are the differences between the vaccines authorized by the FDA?
Two of the vaccines are mRNA vaccines that have a piece of mRNA specific for the SARS-
CoV-2 spike protein. They have similar efficacy and safety profiles. The third vaccine uses
a non-replicating adenovirus to deliver the spike protein into nearby cells. None of the
vaccines use live viruses so there is no risk of infection. The main differences between
the vaccines include the ages of individuals eligible to get the vaccines, the length of time
between doses, the number of doses, the cold chain requirements for storage, and the
preparation of the vaccine. A side by side comparison is below.
Why should I get a vaccine?
All COVID-19 vaccines are effective at preventing COVID-19, hospitalizations and death.
By getting vaccinated, you are reducing your risk of disease, hospitalization,
severe complications, and even death. Reducing the risk of disease also prevents the
health care system from being overwhelmed.
What does it cost to get the vaccine?
COVID-19 vaccines will be available at no cost to individuals, and clinicians administering the
vaccine will be reimbursed for vaccine administration. See guidance on coding and payment.
Pfizer-BioNTech
Moderna
Janssen (J&J)
Ages eligible for vaccine
16 and older
18 and older
18 and older
Length of time between doses
21 days
28 days
n/a single dose
Storage requirements
-80 C; stable at 4 C for
5 days
-20 C; stable at 4 C for
30 days
-20 C; stable at 4 C for
90 days
Preparation of vaccine
Reconstitution of lyophilized
powder—5 doses per vial
No dilution needed—
10 doses per vial
No dilution needed—
5 doses per vial
COVID-19 VACCINE FAQ, CONTINUED
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There have been reports of a few cases
of severe allergic reaction to one of the
components of mRNA vaccines. Individuals
receiving any of the vaccines should be
monitored for 15-30 minutes after injection.
*On 13, the FDA and CDC paused use of the
Johnson & Johnson vaccine to review six
reported U.S. cases of blood clots from the
vaccine. These kind of clots are rare, and the
vaccine hasn’t been confirmed as the cause.
More information will be available after further
investigation. Patients can safely receive the
Moderna or Pfizer vaccines in place of the
Johnson & Johnson vaccine. Final updates at
aafp.org/family-physician/patient-care/
current-hot-topics/recent-outbreaks/covid-19/
covid-19-vaccine/j-j-vaccine-pause.html. The
vaccines have not been associated with
infertility or DNA modifications. Questions
about vaccine side effects? Check with
your family physician.
How long does immunity last?
It is not known how long immunity will last
from the COVID-19 vaccine. In the clinical
trials that have been conducted to date, the
median length of follow-up was two months
for vaccine recipients.
It is also not known how long immunity
from natural infection lasts; there are
reports of waning antibody levels around
three months after infection, and a few
cases of reinfection have been reported.
We do know that seasonal coronaviruses (a
source for the common cold) do not induce
a robust immune response, which leads to
limited immunity to these viruses. It is likely
that a vaccine will have a stronger and
more lasting immune response, but data
are limited and the research is ongoing.
Should I take any pain medications
before getting the vaccine?
No, it is not recommended for people
to take pain relievers before getting the
vaccine as it is not known how these
medications may affect how well the
vaccine works. For tips on relieving pain
and discomfort AFTER the vaccine, visit:
https://www.cdc.gov/coronavirus/2019-
ncov/vaccines/expect/after.html.
How many doses are needed?
Both mRNA vaccines require two doses;
the Pfizer-BioNTech vaccine should be
given 21 days apart and the Moderna
vaccine doses should be spaced 28 days
apart to achieve an effective immune
response. Recipients should get the
second dose from the same manufacturer
as their first dose. However, if they get a
dose of a different vaccine, no additional
doses are needed, and the series is
considered complete. The Johnson &
Johnson vaccine is a single dose.
What are the side effects of the
vaccine?
Data from the clinical trials of all three
candidates indicate that the most common
reactions were pain at the injection site,
fatigue, headache, and muscle aches.
These symptoms are commonly seen with
other vaccines. A few people also reported
fever and nausea.
No serious side effects were seen in the
data reported in the trials. However, the
CDC and the FDA are monitoring the
adverse events or side effects as the
vaccines are distributed to the public.
COVID-19 VACCINE FAQ, CONTINUED
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If more than one vaccine is available,
would taking two different vaccines be
less effective?
There have been no studies conducted
looking at the effectiveness of the use of
different vaccine products to complete the
COVID-19 series. Current guidance states the
same vaccine should be given for both dose
one and two. If different vaccines are given,
the recipient does not need to receive an
additional vaccine.
Who can’t get the vaccine?
Children and adolescents under age 16 are
not eligible to receive the Pfizer-BioNTech
vaccine. Those under age 18 are not eligible
to receive the Moderna or Johnson &
Johnson vaccines as there are not data on
the safety and efficacy in this population.
While pregnant or immunocompromised
individuals were also not included in the first
round of trials, patients who are pregnant,
lactating, or immunocompromised are
able to determine if they wish to receive the
vaccine. These patients are encouraged to
have a discussion on the potential benefits
and risks with their family physician.
As with other vaccines, anyone who has a
fever or other symptoms may not be able to
get the vaccine until their symptoms resolve.
This includes those who have symptoms or
have tested positive for COVID-19. There is
also caution for people with documented
anaphylactic reactions to vaccines. Individuals
with a known allergy to any of the vaccine
components should not be immunized.
Do I still need to wear a mask and
physically distance if I have the vaccine?
Yes! While the vaccines provide protection
against COVID-19 disease, they have not
been shown to prevent infection, so people
who are immunized may still be able to
transmit the virus. In patients who received
the Pfizer-BioNTech or Moderna vaccine, the
high rate of efficacy in preventing disease
was not observed until several weeks after
the second dose of the vaccines. Everyone
will still need to wear a mask and practice
physical distancing until a large section
of the population has been immunized, or
developed immunity which may not be until
late 2021. Even then, more data will be needed
to see how long immunity lasts. Additional
rounds of immunizations may be needed.
If I am vaccinated against COVID-19,
can I still spread the virus to others?
The vaccine trials conducted did not look
at the vaccine’s ability to prevent virus
transmission. We do know the vaccine is
very effective at preventing illness in those
receiving the vaccine. Because there are not
data demonstrating the ability of the vaccines
to prevent viral transmission, it is important
to continue to wear a mask and socially
distance even after getting vaccinated.
Can I get the vaccine if I’ve already
had COVID-19?
Yes, although there are not enough data
currently to determine how prior infection with
COVID-19 affects the efficacy of the vaccine.
It is known that natural immunity to the virus
wanes over time, so currently, under the EUA,
individuals who have previously been infected
are eligible for receiving the vaccine.
COVID-19 VACCINE FAQ, CONTINUED
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Can I get other vaccines, like the flu shot, at the same time as the COVID-19 vaccine?
No, you will need to wait two weeks after getting the COVID-19 vaccine before getting other immunizations.
How do I report symptoms after the vaccine?
As with other vaccines, vaccine recipients are encouraged to report side effects (called adverse
events) to the Vaccine Adverse Event Reporting System (VAERS). This is a nationwide program that
collects data to use as signals of unexpected events from a vaccine. If you have a question on what
might be considered a side effect related to the vaccine, talk with your family physician.
Because any COVID-19 vaccine will be provided under EUA, clinicians will have additional reporting
requirements outlined in the EUA fact sheet from the FDA. Each state and jurisdiction has plans in
place for handling reporting.
In addition to VAERS, the CDC implemented a new, smartphone-based tool called v-safe that sends
text messages to encourage adverse events reports or impact to quality of life. This system requires
the use of a smartphone, and recipients must opt into the system. Information on v-safe is provided
to anyone who gets the vaccine, along with a card indicating which vaccine and dose was given, and
the EUA fact sheet.
If I have allergies, can I get the COVID-19 vaccine?
Yes! Seasonal allergies and even food allergies, including allergies to shellfish and peanuts,
do not exclude you from getting the COVID-19 vaccine. Individuals who had severe reactions,
like anaphylaxis, after a previous dose of an mRNA COVID-19 vaccine or any of its components
(including polyethylene glycol [PEG]) should not get another dose of the Pfizer or Moderna
vaccine. Instead they should receive a dose of the Johnson & Johnson vaccine if it becomes
available again. Individuals who have an allergy to polysorbate or have had a reaction to an
injectable medication or vaccine are not precluded from getting the COVID-19 vaccine, but should
be monitored closely after administration. See more information at https://www.cdc.gov/vaccines/
covid-19/info-by-product/clinical-considerations.html.
Can I get the COVID-19 vaccine if I am pregnant or breastfeeding?
There has been no data on the use of EUA approved COVID-19 vaccines in pregnant or
breastfeeding women. However, these individuals are not excluded from getting the vaccine
and they should talk with their family physician about the risks and benefits of being vaccinated.
COVID-19 VACCINE FAQ, CONTINUED
Additional Resources
• AAFP COVID-19 vaccine webpage: www.aafp.org/covidvaccine
• AAFP’s Johnson & Johnson COVID-19 Vaccine FAQs: https://www.aafp.org/family-physician/patient-care/currenthot-
topics/recent-outbreaks/covid-19/covid-19-vaccine/j-j-vaccine-pause.html
• Familydoctor.org vaccine article: https://familydoctor.org/covid-19-vaccine/
• CDC COVID-19 vaccine webpage: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/index.html
• Pfizer-BioNTech EUA fact sheet: https://www.fda.gov/media/144413/download
• Moderna EUA fact sheet: https://www.fda.gov/media/144638/download
• Janssen (Johnson & Johnson) EUA fact sheet: https://www.fda.gov/media/146305/download
• Coding and payment resources:

a. COVID-19 Vaccine Coverage Requirements and Preliminary Payment Guidance:
https://www.aafp.org/dam/AAFP/documents/advocacy/prevention/vaccines/ES-COVIDVaccineCoveragePay-
ment-121020.pdf

b. First COVID-19 Vaccine CPT Codes Published:
https://www.aafp.org/journals/fpm/blogs/gettingpaid/entry/covid_vaccine_codes.html
References
1. Centers for Disease Control and Prevention. Understanding mRNA vaccines. https://www.cdc.gov/
coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html. Accessed Dec. 12, 2020.
2. Centers for Disease Control and Prevention. Frequently asked questions about COVID-19 vaccine.
https://www.cdc.gov/coronavirus/2019-ncov/vaccines/faq.html. Accessed Dec. 12, 2020
3. U.S. Food and Drug Administration. Vaccines and Related Biological Products Advisory Committee Meeting, Dec. 10,
2020 FDA Briefing Document, Pfizer-BioNTech COVID-19 vaccine. https://www.fda.gov/media/144245/download. Ac-
cessed Dec. 10, 2020.
4. U.S. Food and Drug Administration. Vaccines and Related Biological Products Advisory Committee Meeting, Dec. 17,
2020 FDA Briefing Document, ModernaTX COVID-19 vaccine. https://www.fda.gov/media/144434/download.
Accessed Dec. 17, 2020.
5. U.S. Food and Drug Administration. Vaccines and Related Biological Products Advisory Committee Meeting.
February 28, 2021. FDA Briefing Document. Janssen COVID-19 vaccine. https://www.fda.gov/media/146217/download.
Accessed February 26, 2021.
COM20012111 | Updated April 16, 2021
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