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Pfizer Vaccine vs Moderna Vaccine: Which Should You Get?

writtenByWritten by: Riley McCabe
Riley McCabe

Riley McCabe

Riley has a background in international affairs and enjoys writing about health and public policy subjects. He hopes his work will provide readers with the tools to live happily.

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reviewBy Reviewed by: Leann Poston, M.D.
Reviewer

Leann Poston, M.D.

Leann Poston, M.D. earned her medical degree from the Wright State University Boonshoft School of Medicine. She completed an MBA from Raj Soin College of Business, focusing on healthcare. She is a full-time medical communication writer and educator.

August 26, 2021 Read Time - 10 minutes

*NOTE:  Due to a lack of scientific data at this time, PlushCare physicians do not prescribe ivermectin, hydroxychloroquine, or azithromycin/other antibiotics to treat COVID-19.

Can I Choose Between the Pfizer and Moderna Vaccines?

Vaccines are much more accessible in the U.S. than just a few months ago. Today, anyone who wants to be vaccinated can be. 

The Pfizer and Moderna COVID-19 vaccines were both approved by the FDA for public rollout in December 2020, while the Johnson & Johnson vaccine was approved in February 2021.

The FDA fully approved the Pfizer-BioNTech COVID-19 vaccine on August 23, 2021. As the first FDA-approved COVID-19 vaccine, this marks a major milestone in fighting the pandemic. The FDA’s approval of the vaccine’s safety and quality may provide more confidence in getting vaccinated.

The initial rollout of the vaccine worked in phases, with healthcare workers, essential workers, the elderly, and other high-risk populations receiving the first doses produced. 

Today, the Pfizer-BioNTech vaccine is approved for anyone 12 or older and clinical trials are underway for vaccinating children aged 5 to 11. 

Moderna is approved for adults age 18 and older. Children aged 12 and up show a good response to the vaccine and it is being tested in children ages 5-11. 

The Johnson & Johnson vaccine is approved for adults 18 and older. 

Given current developments surrounding the COVID-19 pandemic, it’s worth knowing the difference between the Pfizer and the Moderna vaccines, as well as the Johnson & Johnson vaccine.

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Here Is How the Pfizer and Moderna Vaccines Work

Both the Pfizer and Moderna mRNA COVID-19 vaccines have been granted emergency use authorization by the FDA. Each is administered in two doses. Each vaccine is considered highly effective at preventing COVID infection. 

Here is a comparison of how the two vaccines work:

PfizerModerna
Effectiveness95% effective 7 days after 2nd dose94.1% effective 14 days after 2nd dose
DosageRequires 2 dosesRequires 2 doses
Inoculation Period21 day waiting period between doses28 day waiting period between doses
Vaccine levels30 micrograms of actual vaccine100 micrograms of actual vaccine
TemperatureArrives between -112°F to -76°FArrives between 13°F and 5°F
Shelf life Must be used within 5 days after thawingFridge stable for 30 days, room temperature stable for 12 hours
Pfizer vs Moderna Vaccine Comparison

Have questions about the COVID-19 vaccine and whether it is right for you? Talk to our doctors. If you are unsure about your vaccine options, you can make an online appointment to talk to our doctors about which vaccines would work best for you.



How Do the COVID-19 Vaccines Work?

Both the Pfizer and Moderna vaccines have undergone thorough testing to ensure they are effective at preventing COVID-19 infection and safe for widespread public use. In fact, the vaccines themselves are fairly similar in how they work.

Both Pfizer and Moderna have developed mRNA vaccines. Such a vaccine delivers a synthetic genetic recipe mimicking material from the spike protein of the virus that teaches our cells how to make a harmless protein unique to the COVID-19 virus.

According to the CDC, “After our cells make copies of the protein, they destroy the genetic material from the vaccine. Our bodies recognize that the protein should not be there and build T-lymphocytes and B-lymphocytes that will remember how to fight the virus that causes COVID-19 if we are infected in the future.”

Both the Pfizer and the Moderna vaccines use this exact mRNA process. 

The Johnson & Johnson vaccine, also known as the Janssen COVID-19 vaccine, is a viral vector vaccine. The Johnson & Johnson vaccine uses a virus known as adenovirus type 26 (Ad26) to deliver a piece of DNA that is used to make the “spike” protein. According to the FDA, “After a person receives this vaccine, the body can temporarily make the spike protein, which does not cause disease, but triggers the immune system to learn to react defensively, producing an immune response against SARS-CoV-2.”

COVID-19 Vaccine Efficacy

Vaccine efficacy continues to be studied as new variants are causing infection and the time between vaccination and potential exposure is increasing. 

How effective is the Pfizer vaccine?

  • The Pfizer vaccine showed an efficacy of 95% at preventing symptomatic COVID-19 infection starting 7 days after the second dose was administered based on its initial phase 3 data. 

How effective is the Moderna vaccine?

  • The Moderna vaccine was 94.1% effective at preventing symptomatic COVID-19, starting from 14 days after the second dose was administered based on its initial phase 3 data. 

How effective is the Johnson & Johnson vaccine?

  • Overall, across all countries where trials were conducted, the Johnson & Johnson vaccine showed an efficacy of 67% at preventing moderate to severe/critical COVID-19 infection at least 14 days after vaccination. In the United States, Johnson & Johnson found that the vaccine efficacy was 72%. The vaccine was also 85% effective in preventing severe COVID-19 illness and death occurring at least 28 days after vaccination.

Both the Pfizer and the Moderna vaccines, as well as the Johnson & Johnson vaccine, have worked well to reduce the risk of COVID-19. 

All three vaccines have been tested against the delta variant. 

  • Pfizer-BioNTech: two studies have shown the Pfizer vaccine is 88% effective against symptomatic disease and 96% effective against hospitalization. However, a report from Israel showed lower effectiveness.
  • Moderna: Moderna reported that its vaccine was two times weaker than against the other variants. These results are being further studied. 
  • Johnson & Johnson: Johnson & Johnson reported that its effectiveness against the Delta variant is similar to the original strain. More studies are in progress. 

The more contagious Delta variant has spread across the U.S.It is twice as contagious as previous variants and may cause more serious illness, according to the CDC

Breakthrough infections are occurring in vaccinated individuals, though at a much lower rate than infections in the unvaccinated. 

Fully vaccinated people can spread the Delta variant of COVID-19 to others, even when they are asymptomatic. 

COVID-19 Vaccine for Immunocompromised People

The CDC now recommends that “people who are moderately to severely immunocompromised should receive an additional dose of mRNA COVID-19 vaccine after the initial 2 doses.”

The CDC also explained this dose for immunocompromised people “is not the same as a booster dose, given to people when the immune response to a primary vaccine series is likely to have waned over time.”

COVID-19 Vaccine Booster Shots

The CDC is prepared to offer COVID-19 vaccine booster shots to all Americans starting the week of September 20 and 8 months after a person’s second dose. While this development is still ongoing, people who were vaccinated the earliest, such as health care workers, seniors,  and nursing home residents, are likely to be eligible for a booster shot.

Dosage of COVID-19 Vaccine

Both the Pfizer and Moderna Vaccine require two shots. A priming dose is followed by a booster shot after an allocated period of time.

For Pfizer, you must wait 21 days between the initial shot and your booster. For Moderna, the waiting period between shots is 28 days.

Each Pfizer vaccination administers 30 micrograms of actual vaccine. Moderna gives much larger doses, at 100 micrograms. Despite the disparity in dosage, the efficacy between the two vaccines is nearly identical.

The Johnson & Johnson vaccine is administered as a single dose (0.5 mL).

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    Our doctors operate in all 50 states and same day appointments are available every 15 minutes.

  • See a doctor, get treatment and a prescription at your local pharmacy.

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Storage Requirements

Both the Pfizer and the Moderna vaccine require “cold chain,” the term used to describe a temperature-controlled supply chain. In this respect, however, the vaccines differ greatly.

Pfizer-BioNTech

According to the CDC, after being shipped, the Pfizer vaccine arrives at a temperature between -112°F to -76°F in a container with dry ice. 

Before mixing, the vaccine may be stored in an ultra-cold freezer between -80°C and -60°C (-112°F and -76°F).

The Pfizer vaccine can also be stored in a freezer between -25°C and -15°C (-13°F and 5°F) for up to 2 weeks or a refrigerator between 2°C and 8°C (36°F and 46°F) for up to 31 days.

Moderna

The Moderna vaccine arrives frozen between -58°F and 5°F, according to the CDC. Unpunctured vials may be stored in the freezer between -50°C and -15°C (-58°F and 5°F) or they may be stored in the refrigerator between 2° to 8°C (36° to 46°F) for up to 30 days. 

Johnson & Johnson

According to the CDC, the Johnson & Johnson vaccine arrives at a refrigerated temperature between  36° and 46° Fahrenheit; it is stored in a refrigerator and not frozen. After the multidose vial seal is punctured, the vaccine can be stored in the refrigerator between 36° Fahrenheit and 46° Fahrenheit for up to 6 hours or at room temperature (up to 77° Fahrenheit) for 2 hours.


Read: COVID-19 Mental Health Center


Side Effects of the Coronavirus Vaccine

The most common side effects of the three vaccines are:

  • Pain, swelling, or redness at the injection site
  • Swollen lymph nodes in the armpit
  • Headache
  • Joint or muscle pain
  • Tiredness
  • Nausea and vomiting
  • Fever and chills
covid-19-side-effects

Some people in clinical trials also reported having a fever, side effects were more common and temporarily disabling after the second dose. Younger adults with more robust immune systems reported more intense side effects.

It’s worth noting that these side effects are signs of the immune system working properly. An immune reaction commonly brings about the effects described above, and those with stronger immune systems may counterintuitively feel stronger side effects.


Read: What to Expect After Getting the COVID-19 Vaccine


Is the Coronavirus Vaccine Safe?

Yes, the coronavirus vaccine is safe. Severe allergic reactions called anaphylaxis rarely occur and can be treated. 

On April 13, 2021, the FDA and CDC called for a pause in the usage of the Johnson and Johnson vaccine, due to reports of rare blood clots among people who have received the vaccine in the U.S. The pause on the Johnson and Johnson vaccine was lifted on April 23, 2021, by federal health officials.   

In about 12.6 cases per million second doses administered, young adults have inflammation of the heart muscle or the outer lining of the heart. In most cases, the inflammation gets better on its own. This important side effect prompted the FDA to place a warning label on both the Pfizer and Moderna vaccines. 

The FDA has placed two warning labels on the Johnson & Johnson vaccine. One warning was placed after rare cases of the neurological disorder Guillain-Barre ́ syndrome was reported in a small number of people. The second warning was added, after an investigation, to warn about a potentially serious blood clotting disorder that also occurred in a small number of recipients. 

Every medication and vaccination has side effects. Ideally, every vaccine and every medication would be 100% effective and 100% safe. This is an impossible goal because we are all different. Our genetic differences determine how we metabolize medications and react to infections.

We all must weigh the risks versus benefits of our choices. The Delta variant is more infectious, causes higher viral loads in infected people, and potentially causes more serious illness. If you have not been vaccinated, speak with your doctor about your concerns and work together to get factual information about your personal risks and benefits. 

Which Vaccine Should I Get?

Each of the vaccines has risks that may be higher in some populations than others. Speak with your doctor about your risk for an allergic reaction, blood clots, Guillain-Barre ́ syndrome, and myocarditis to determine which vaccine provides the greatest benefits for you, with the lowest risks. In the great majority of people, all three vaccines will be equally safe and effective. 

If you believe you may have been exposed to or are experiencing symptoms of COVID-19, quarantine, and contact a doctor immediately. With PlushCare, you can set up an online appointment in mere minutes with one of our trusted doctors. Just click here to set up your appointment.


Read More About COVID-19 Vaccines


Sources:

PlushCare is dedicated to providing you with accurate and trustworthy health information.

cdc.gov. Understanding mRNA Vaccines. Accessed on January 3, 2021 at https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html

cdc.gov. How Vaccines Work. Accessed on January 3, 2021 at https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/how-they-work.html

cdc.gov. COVID-19 Vaccines for Moderately to Severely Immunocompromised People.  Accessed on August 25, 2021 at https://www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/immuno.html 

cdc.gov. Joint Statement from HHS Public Health and Medical Experts on COVID-19 Booster Shots. Accessed on August 26, 2021 at https://www.cdc.gov/media/releases/2021/s0818-covid-19-booster-shots.html 

fda.gov. FDA Approves First COVID-19 Vaccine. Accessed on August 25, 2021 at https://www.fda.gov/news-events/press-announcements/fda-approves-first-covid-19-vaccine

fda.gov. FDA Issues Emergency Use Authorization for Third COVID-19 Vaccine. Accessed March 3, 2021 at https://www.fda.gov/news-events/press-announcements/fda-issues-emergency-use-authorization-third-covid-19-vaccine

genome.gov. Messenger RNA. Accessed on January 3, 2021 at https://www.genome.gov/genetics-glossary/messenger-rna

Washington Post. FDA, CDC call for pause in use of Johnson & Johnson vaccine after ‘extremely rare’ cases of blood clots. Accessed on April 15, 2021 at https://www.washingtonpost.com/health/2021/04/13/johnson-and-johnson-vaccine-blood-clots/

Most PlushCare articles are reviewed by M.D.s, Ph.Ds, N.P.s, nutritionists and other healthcare professionals. Click here to learn more and meet some of the professionals behind our blog. The PlushCare blog, or any linked materials are not intended and should not be construed as medical advice, nor is the information a substitute for professional medical expertise or treatment. For more information click here.

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