Pfizer vs. Moderna Vaccines: Similarities and Differences

7 Min Read Published December 21, 2020
Pfizer vs. Moderna Vaccines: Similarities and Differences

By, Kathleen Gaines, MSN, RN, CBC

As 2020 comes to an end, there is hope as two COVID-19 vaccines have recently been approved by the FDA and have been shipped to hospitals across the country. While the ongoing fight against the coronavirus is far from over, nurses are beginning to get vaccinated in order to create herd immunity and slow the progression of the ongoing pandemic. Both vaccinations were approved following a new emergency use authorization (EUA) from the US Food and Drug Administration (FDA). 

Currently, there are TWO viable vaccines available to nurses throughout the United States, one produced by Pfizer-BioNTech and the other Moderna. Unfortunately, nurses do not currently have the option to pick which vaccine they would like to receive. The vaccines provide virtually the same coverage in terms of effectiveness and have numerous other similarities. There are a few differences though.  

It’s important to note that BOTH vaccines require TWO dosages for effective immunity. You must receive the same second dose as the first. For example, if your first vaccine dose was Pfizer-BioNTech then you must receive a second dose of Pfizer-BioNTech.  

Pfizer and German Biotechnology Company BioNTech developed the first to market COVID-19 vaccine that was authorized by the FDA while Moderna, a Cambridge, Massachusetts-based biotechnology company developed the second to market COVID vaccine.  

>> Show Me Online RN-to-BSN Programs

Here is a quick and easy comparison chart about the two different vaccines. Read below for additional information. 

How do COVID-19 vaccines work? 

Both vaccines work using messenger RNA (mRNA). mRNA vaccines work by encoding a portion of the spike protein from on the surface of SARS-CoV-2. This is the virus that causes COVID-19. 

According to the Centers for Disease Control and Prevention (CDC), once the mRNA is inside the immune cells, the cells use them to make the corresponding protein piece. The encoded proteins spark an immune response that allows the body to fend off future illnesses by the COVID virus. Once your body creates that immune response, both the protein and mRNA are eliminated, while the antibodies stick around to protect you in the future. 

While mRNA vaccines are different than other vaccines, such as the flu vaccine, no actual virus is needed to make these vaccines.  

Side effects of the COVID-19 vaccines 

Both vaccinations are administered in the deltoid muscle via IM injection. The FDA reports similar side effects for both vaccines including, 

  • Pain at the injection site 
  • Tiredness 
  • Headache 
  • Muscle pain 
  • Chills 
  • Joint pain 
  • Fever 
  • Injection site swelling 
  • Injection site redness 
  • Nausea 
  • Vomiting 
  • Fever 

It’s important to note that the aforementioned side effects are a sign of your immune system working and not a sign that the vaccine is unsafe and/or developing an infection of COVID-19. More severe reactions were not seen in clinical trials according to the FDA. However, it is important to note that the FDA does not currently advise individuals with life-threatening allergies to foods and/or medications to receive the vaccination at this time.  

Age Authorization 

  • Pfizer-BioNTech vaccine is currently authorized for people aged 16 years and older.
  • Moderna’s vaccine has been approved for individuals 18 and older. According to Moderna’s website, they have currently started clinical trials with patients in the 12 to 17-year range.  

Vaccine Efficacy 

Both vaccines have astounding effectiveness according to their clinical trials. Moderna reports a 94.1% vaccine efficacy against COVID-19 and 100% effectiveness against severe COVID-19.  

Pfizer-BioNTech on the other hand demonstrates a 95% effectiveness against COVID-19 beginning 28 days after the first dose.  

Due to the newness of the vaccine, it is impossible to determine what the overall effectiveness will be once the vaccine is distributed to the larger population including those that have preexisting conditions, work in high-risk fields with repeated exposure to COVID, and the elderly population. However, both vaccines currently reduce the risk of severe COVID-19 disease.  

Storage Requirements 

Currently, storage requirements are one of the biggest differences noted between the Pfizer-BioNTech and Moderna vaccine. The ultra-cold storage requirement makes it difficult to distribute and store properly. While this may not be an issue for hospitals and large healthcare organizations, it may be an ongoing concern with regards to distribution to doctors’ offices, pharmacies, and/or public health clinics.  

Moderna’s vaccine must be shipped at -4 Fahrenheit which is the equivalent of a regular refrigerator freezer while  Pfizer’s must be shipped and stored at -94 Fahrenheit which requires an ultra-cold freezer that needs to be topped with dry ice every five days.  

After thawing, a vial of the Pfizer vaccine must be used within five days; Moderna’s is stable at fridge temperature for 30 days and at room temperature for 12 hours. 

The Road to FDA Approval 

During Phase 3 of the Pfizer-BioNTech COVID-19 vaccine study, all primary efficacy endpoints were met allowing the FDA to provide emergency authorization. During Phase 3, Pfizer-BioNTech had the following findings according to their website,

  • Primary efficacy analysis demonstrates BNT162b2 to be 95% effective against COVID-19 beginning 28 days after the first dose; 170 confirmed cases of COVID-19 were evaluated, with 162 observed in the placebo group versus 8 in the vaccine group 
  • Efficacy was consistent across age, gender, race, and ethnicity demographics; observed efficacy in adults over 65 years of age was over 94% 
  • Safety data milestone required by the U.S. Food and Drug Administration (FDA) for Emergency Use Authorization (EUA) has been achieved 
  • Data demonstrate vaccine was well tolerated across all populations with over 43,000 participants enrolled; no serious safety concerns observed; the only Grade 3 adverse event greater than 2% in frequency was fatigue at 3.8% and headache at 2.0% 
  • Companies plan to submit within days to the FDA for EUA and share data with other regulatory agencies around the globe 
  • The companies expect to produce globally up to 50 million vaccine doses in 2020 and up to 1.3 billion doses by the end of 2021 
  • Pfizer is confident in its vast experience, expertise, and existing cold-chain infrastructure to distribute the vaccine around the world 

Moderna reported the following findings in the Phase 3 study for COVID-19 vaccine according to the website,  

  • Primary efficacy analysis of the Phase 3 COVE study of mRNA-1273 involving 30,000 participants included 196 cases of COVID-19, of which 30 cases were severe 
  • Vaccine efficacy against COVID-19 was 94.1%; vaccine efficacy against severe COVID-19 was 100% 
  • mRNA-1273 continues to be generally well tolerated; no serious safety concerns identified to date 
  • Phase 3 COVE Study has exceeded 2 months of median follow-up post-vaccination as required by the U.S. FDA for Emergency Use Authorization (EUA) 
  • Moderna plans today to request EUA from the U.S. FDA, to apply for conditional marketing authorization with the European Medicines Agency (EMA), and to progress with the rolling reviews, which have already been initiated with international regulatory agencies 

FDA Approval Process 

While the development of the COVID-19 vaccine and approval process may have seemed rushed to some, both the Pfizer-BioNTech and Moderna vaccine went through all of the appropriate clinical trials, development, and regulatory requirements. The aforementioned vaccines were given emergency use authorization (EUA). On February 4, 2020, the Secretary of the Department of Health and Human Services announced a public health emergency that has the potential to affect national security as well as the health and well-being of Americans and citizens living abroad. As a result of this announcement, “the FDA may issue a EUA to allow unapproved medical products or unapproved uses of approved medical products to be used in an emergency to diagnose, treat, or prevent COVID-19 when there are no adequate, approved, and available alternatives.” 

So what does an Emergency Use Authorization (EUA) really mean?  

The EUA is different than FDA approval of a vaccine in that a vaccine available under a EUA is not approved. The FDA evaluates the available data and evidence and determines whether the vaccine may be effective while assessing any known or potential risks and any known or potential benefits. If everything checks out – then the vaccine is given an emergency use authorization. The vaccine manufacturer will then apply for standard FDA approval; however, in the meantime, the vaccine can be widely distributed to the public.  

The Unknown 

Despite two new to market COVID vaccines, healthcare professionals are hopeful and optimistic about the future. Nurses and other healthcare professionals are lining up for the vaccine throughout the United States. Even though there is ongoing excitement for the light at the end of the tunnel, many frontline workers in healthcare have yet to receive the vaccine. Furthermore, both vaccine manufacturers indicate that effectiveness isn’t until after the second dose and there has been no research indicated whether the vaccine is effective against the asymptomatic spread.  Making an informed decision regarding whether or not to receive the COVID-19 vaccine is your right as a healthcare professional. For more information visit the FDA, Moderna, and Pfizer websites. Once given the opportunity to receive the vaccine, most nurses would agree – sign us up! 

Additional Information 

Kathleen Gaines
Kathleen Gaines
News and Education Editor

Kathleen Gaines (nee Colduvell) is a nationally published writer turned Pediatric ICU nurse from Philadelphia with over 13 years of ICU experience. She has an extensive ICU background having formerly worked in the CICU and NICU at several major hospitals in the Philadelphia region. After earning her MSN in Education from Loyola University of New Orleans, she currently also teaches for several prominent Universities making sure the next generation is ready for the bedside. As a certified breastfeeding counselor and trauma certified nurse, she is always ready for the next nursing challenge.

Read More From Kathleen
Go to the top of page