The correct answer is:

The Moderna, Pfizer-BioNTech, and J/J/Janssen COVID-19 vaccines all invade host cells to induce intracellular manufacture a piece of SARS-CoV-2 RNA that is displayed on the host's cell surface where it triggers an immune response.

Key Point:

The J/J/Janssen vaccine is known as a vector vaccine (using an inactivated adenovirus as the vector) whereas the other two are known as mRNA vaccines. This labeling has led to a misperception that the vaccines differ from one another more than they actually do. The 3 vaccines all deliver a piece of SARS-CoV-2 RNA into the host’s cell to be replicated and then displayed on the host’s cell surface.

Explanation:

The 3 vaccines differ from one another in that the J/J/Janssen vaccine relies on an inactivated adenovirus vector to shuttle an attached piece of the SARS-Co-V2 RNA into the host cell, whereas the other 2 vaccines rely upon an oil emulsion (instead of an inactivated viral vector) to deliver the piece of SARS-CoV-2 RNA into the host’s cell. However, the bottom line is that all 3 vaccines deliver a piece of SARS-CoV-2 RNA into the host's cell. The host cell then replicates and displays the piece of SARS-CoV-2 on its cell surface. All 3 vaccines trigger both humoral and cellular immunity to SARS-CoV-2.

The J/J/Janssen vaccine results in a lower protection from COVID_19 (63% effective) than the other 2 vaccines (roughly 95% effective). This appears to partly be due to the fact that the inactivated adenovirus vector of the J/J/Janssen vaccine is also replicated inside the host cell and displayed on the cell surface, along with the piece SARS-CoV-2 RNA. Since most people have already mounted immune responses to past adenoviral infections, the co-expressed pieces of adenovirus RNA seem to elicit a rapid immune response from immunological memory prior to the host mounting a new immune response to the unknown piece of SARS-CoV-2 RNA.

However, most importantly – all 3 vaccines are highly (nearly 100%) effective at preventing BOTH hospitalizations and death from COVID-19, thus converting SARS-CoV-2 infection into a sometimes uncomfortable but no longer dangerous infection.

For all 3 vaccines, a vial can only be used for 6 hours of puncture. Different from the other 2 vaccines, the J/J/Janssen vaccine should never be frozen.

Advantages of the J/J/Janssen vaccine are ease of transportation (no freezing) and the fact that a single inoculation suffices to deliver highly effective (essentially 100%) protection from severe disease. Also, population acceptance seems to be higher for the J/J/Janssen vaccine due to the fact that the Moderna and Pfizer BioNTech vaccines are more novel (e.g. less proven) than the J/J/Janssen vector vaccine (which in reality is also fairly novel and unproven).

Pearl: All 3 vaccines result in the same fairly common side effects of fatigue, headache, myalgias, and fever. The J/J/Janssen vaccine results in maximum side effects 1-2 days after vaccination whereas Moderna results in side effects within hours of vaccination and Pfizer’s side effects tend to peak within 24 hours. During vaccination, people must be made aware of the correct timeline of their specific vaccine’s side effects.

Side effects to the COVID-19 vaccines tend to be more pronounced in younger patients (a fact most thoroughly documented for the J/J/Janssen vaccine.

References:

Centers of Disease Control and Prevention (CDC): Information About Johnson & Johnson’s Janssen COVID-19 Vaccine. (Updated March 4 2021; Accessed March 13, 2021).

Chen Fang, PharmD, RPh. COVID-19 Vaccine Efficacy After First Dose: Pfizer, Moderna, AstraZeneca. Infectious Disease Advisor. (Updated February 25 2021; Accessed March 13, 2021)

Kraemer EJ. Pros and Cons of Adenovirus-Based SARS-CoV-2 Vaccines. Molecular Therapy. Oct 9, 2020

FDA Janssen COVID-19 Vaccine EUA Fact Sheet for Media Release. (Released February 27, 2021; Accessed March 13, 2021)

Centers of Disease Control and Prevention (CDC): Covid-19 Vaccination. (Updated March 12 2021; Accessed March 13, 2021).