Comparing Vaccines

 Comparing Vaccines: Pfizer vs. Moderna vs. Johnson and Johnson 

    

    As of February 3, 2021, two vaccines, developed by the companies Pfizer and Moderna, have already been approved in the United States by the Food and Drug Administration (FDA). Currently, other vaccines that have just completed phase 3 clinical trials are seeking Emergency Use Authorization by the FDA; one of the most notable candidates is a vaccine developed by the company Johnson and Johnson. As more vaccines become available to the public, some may be wondering which vaccine they should get and why? Is one type of vaccine more effective than the others? What are the side effects of each of the vaccines? This post does a side-by-side comparison of the current leading vaccines developed by the companies Pfizer, Moderna and Johnson & Johnson. Information is taken from peer-reviewed clinical trial results cited in previous posts about these vaccines as well as newer research taken from reliable sources.

How Each Vaccine Works

Pfizer and Moderna: Both the Pfizer and Moderna vaccines are mRNA based. This means that instead of using a weakened form of the virus to trigger an immune response, an mRNA vaccine gives our cells the instruction to make a SARS-CoV-2 spike protein that can trigger an immune response against COVID-19 infection.

Johnson and Johnson: This vaccine is a replication-incompetent adenovirus serotype 26 vector vaccine. Unlike mRNA vaccines, this vaccine uses a weakened form of an adenovirus, which encodes a SARS-CoV-2 protein that generates an immune response in our bodies. In accordance with the name of this vaccine type, the adenovirus is incapable of replicating in our bodies after injection.

Trial Conducting Periods and Size

Pfizer: Pfizer's phase 3 trial began on July 27, 2020 and enrolled a total of 43,538 participants. 

Moderna: Moderna's phase 3 trial also began on July 27, 2020 and enrolled 30,000 participants ages 18 and older.

Johnson and Johnson: Although a detailed report of this vaccine candidate's phase 3 trial has yet to be published, the clinical trial for this vaccine was conducted the most recently compared to Moderna and Pfizer. The phase 1-2a trial was conducted from July-November 2020. Unlike Moderna and Pfizer's vaccine trials, Johnson and Johnson's phase 3 trial involved patients exposed to the new COVID-19 strains including variant B.1.315 from South Africa. The vaccine demonstrated a 57% efficacy against this variant.

Vaccine Efficacy

Pfizer: Phase 3 results found that the vaccine showed 95% efficacy against COVID-19 symptoms 7 days after a second dose and its efficacy was consistent across gender, age, race and ethnicity groups. There were no deaths that occurred in this study. The vaccine also significantly reduced the risk of severe COVID-19. Anthony Fauci, the director of the Nation Institute of Allergy and Infectious Diseases, acknowledged that the vaccine is less effective against the South Africa B.1.351 strain (yet still worth taking) but offers strong protection against the B.1.1.7 variant. 

Moderna: The Moderna vaccine demonstrated a 94.1% efficacy against COVID-19 symptoms 14 days after the second dose. Its efficacy was consistent across gender, age, race and ethnicity demographics in its phase 3 trial. In the same trial, the vaccine was found to be 100% effective against severe COVID-19. No COVID-19 related deaths were reported in participants who received the vaccine. Similar to the Pfizer vaccine, the Moderna vaccine is just as effective against the B.1.1.7 variant but research found a reduction in efficacy against the B.1.351 variant. However, the vaccine still offers protection against the B.1351 variant.

Johnson and Johnson: This vaccine candidate was 66% effective in preventing COVID-19 symptoms and 85% effective in preventing severe COVID-19 28 days after vaccination as reported in its phase 3 trial. Johnson and Johnson also announced that their vaccine "demonstrated complete protection against COVID-19 related hospitalization and death." Vaccine protection was also consistent across gender, age, race and ethnicity groups and showed 57% efficacy in South Africa where 95% cases were due to infection from the B.1.351 variant.

Adverse Events and Who Shouldn't Receive the Vaccine

Pfizer: The side effects for Pfizer's vaccine include fatigue, headache, chills, and muscle pain, with effects increasing after the second dose. The Centers for Disease Control and Prevention, or CDC, has reported 11.1 cases per million vaccine doses administered of anaphylaxis, a life-threatening allergic reaction. However, there were no anaphylaxis-related deaths and most people who developed anaphylaxis had a history of allergic reactions. That said, those who have serious allergic reactions to vaccine ingredients or a history of serious allergic reactions should not receive the vaccine.

Moderna: Intensity of adverse events increased after the second dosage. These side effects include fever, muscle aches and headaches. According to the CDC, there are a reported 2.5 cases of anaphylaxis per million Moderna vaccine doses but no reported anaphylaxis-related deaths. Similar to the Pfizer vaccine, people with a history of serious allergic reactions or have allergic reactions to vaccine ingredients should not receive the vaccine.

Johnson and Johnson: Although detailed results of adverse events from the phase 3 trail have not been released, the most frequent adverse events presented in the phase 1-2a trial include fatigue, headache and muscle pain. So far, there have not been any reported cases of anaphylaxis. As with any vaccine, those with serious allergic reactions to vaccine ingredients or a history of allergic reactions should not be receiving a vaccine.

Dosage, Cost and Storage

Pfizer: The Pfizer vaccine requires 2 doses of 30 micrograms 3 weeks apart. Each dose is expected to cost $19.50. Pfizer's vaccine has an extremely low storage temperature of -94 degrees fahrenheit or -70 degrees celsius. This requires the use of an ultracold freezer which is not available in most doctor's offices or pharmacies.

Moderna: Moderna's vaccine also calls for 2 doses but unlike Pfizer, each dose contains 100 micrograms of the vaccine and should be taken 4 weeks apart. The company announced that it plans to sell each dose for around $25. The storage temperature for this vaccine is -4 degrees fahrenheit or -20 degrees celsius and can be stored in a standard refrigerator freezer.

Johnson and Johnson: The Johnson and Johnson vaccine is a single-shot vaccine; it has not only a logistical advantage but also possesses the potential to vaccinate people twice as fast compared to the Pfizer and Moderna vaccines. As of February 2, 2021 the company has not yet released information for the cost of each vaccine dose. Johnson and Johnson's vaccine can remain stable for at least 3 months at temperatures between 36-46 degrees fahrenheit (2-8 degrees celsius), requiring only a regular refrigerator. In terms of dosage and storage, the Johnson and Johnson vaccine is more practical for developing countries, as it is much easier to store and execute vaccination compared to the Pfizer and Moderna vaccines.

Conclusion

    Each vaccine has its own advantages and disadvantages in terms of efficacy, adverse events, dosage, storage, and cost. Knowing all the pros and cons of the major vaccines is important if you plan to receive a vaccination. Although each vaccine has minor drawbacks, it's important to remember that unless you have a serious allergic reaction to vaccine ingredients, receiving any one of these COVID-19 vaccines is better than not getting one at all. The Pfizer, Moderna and Johnson and Johnson vaccines all offer a significant protection against coronavirus infection which can slow the spread of the pandemic and help things return back to normal.

Sources

1. “Allergic Reactions Including Anaphylaxis After Receipt of the First Dose of Moderna COVID-19 Vaccine - United States, December 21, 2020–January 10, 2021.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 28 Jan. 2021, www.cdc.gov/mmwr/volumes/70/wr/mm7004e1.htm?s_cid=mm7004e1_w.

2. “Four COVID Vaccines Compared.” WebMD, WebMD, 29 Jan. 2021, www.webmd.com/vaccines/covid-19-vaccine/news/20201214/closer-look-at-three-covid-19-vaccines.

3. Jennings, Katie. “How Much Will A Covid-19 Vaccine Cost?” Forbes, Forbes Magazine, 17 Nov. 2020, www.forbes.com/sites/katiejennings/2020/11/17/how-much-will-a-covid-19-vaccine-cost/.

4. “Johnson & Johnson Announces Single-Shot Janssen COVID-19 Vaccine Candidate Met Primary Endpoints in Interim Analysis of Its Phase 3 ENSEMBLE Trial.” Johnson & Johnson, 29 Jan. 2021, www.jnj.com/johnson-johnson-announces-single-shot-janssen-covid-19-vaccine-candidate-met-primary-endpoints-in-interim-analysis-of-its-phase-3-ensemble-trial.

5. “Understanding MRNA COVID-19 Vaccines.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 18 Dec. 2020, www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html.

6. Wu, Kai, et al. “MRNA-1273 Vaccine Induces Neutralizing Antibodies against Spike Mutants from Global SARS-CoV-2 Variants.” BioRxiv, Cold Spring Harbor Laboratory, 1 Jan. 2021, www.biorxiv.org/content/10.1101/2021.01.25.427948v1.