J&J is approved … so, which vaccine to choose?

Most “experts” say: “Whichever is available to you first”

The J&J vaccine was approved yesterday and begins distribution this week.

So, if you haven’t already been vaccinated, you might want to know how the vaccines work and how they stack up against one another.

The topline:

The 3 currently relevant brands (Pfizer, Moderna, J&J) are “well tolerated” (i.e. they exhibit few or no side effects) and provide high levels of protection …  with near total protection against hospitalization or death.

In clinal trials, Pfizer & Moderna scored higher in overall protection (roughly 95% against symptomatic infections) than the J&J vaccine (72%) in the U.S.

Most experts consider the difference in effectiveness rates to be more a function of when and where the clinical trials were done than the relative effectiveness of the vaccines.

Specifically, the J&J trial was done in a more “hostile” Covid environment: a higher prevalence of Covid and emergence of new Covid strains (especially the South African variant).


Regarding the variants…

“Laboratory studies and clinical-trial data suggest that all of the Covid  vaccines will provide significant protection (i.e. greater than 50% effectiveness) against emerging strains of the Covid virus.”  Source

It’s highly likely that an additional shot — either a booster or a reformulation — will eventually be required for all brands and types of vaccines to combat the variant strains.


It’s uncertain how effective the vaccines are preventing asymptomatic infections or how long the vaccines provide immunity against serious symptoms.

But, the consensus seems to be that there is very high protection against asymptomatic infections … and that the immunities last for at least several months, maybe longer.

That said, annual shots seem to be likely.

Again, the most compelling immediate effectiveness result to consider: all brands claim near total protection against hospitalization and death with unlikely side effects.

My take: Call it a push on effectiveness.


The J&J vaccine is easier to distribute since it requires less demanding refrigeration.

So, once production is ramped up, it will probably be more ubiquitous in rural areas and in low volume vaccination outlets (e.g. doctor’s offices, urgent care clinics and smaller pharmacies).

As well publicized, Pfizer & Moderna are currently administered in 2 doses with the 2nd dose following 3 or 4 weeks after the 1st.

The J&J vaccine only requires a single dose, making it a good fit for, say, high volume mass vaccination sites and for people who want the convenience of one & done (e.g. workers who are schedule constrained or people with limited access to distribution sites).

The Pfizer & Moderna vaccines are likely to be concentrated in, say, public health department vaccination clinics, targeted to high vulnerability populations.

My take: Beggars can’t be choosers. Practically speaking, you may not have a choice.


That’s probably all that you really need to know, but if you’re interested in the comparative science of the vaccines, keep reading…


The New York Times ran a series on how the different vaccines work.

How the J&J vaccine works.
NYT J&J (PDF w/ HomaFiles highlighting)

How the Moderna vaccine works.
NYT Moderna (PDF w/ HomaFiles highlighting)

Note: The Pfizer & Moderna vaccines are both mRNA vaccines that work essentially the same.

The articles are concise, translated into layman-speak and include great explanatory diagrams.

They are well worth reading!


For a quick read, here’s the essence…

There are 2 different “modalities”:

  • Pfizer and Moderna are Messenger RNA  vaccines (RNA: RiboNucleic Acid) which is shorthanded as mRNA
  • J&J is called a “Viral Vector” vaccine (VV)

Predecessor vaccines (e.g. for the flu) that inject small amounts of a pathogen (i.e. the virus) to trigger an immune response.

Both mRNA and VV vaccines interact with a body’s cellular DNA.

Both Pfizer & Moderna mRNA vaccines are single- stranded RNA that penetrates our bodies’ cells and “instructs” the cell to produce proteins that elicit an immune system response: the production and circulation of virus destroying antigens.

J&J is a more durable double-stranded DNA that not only penetrates cells  but, more specifically penetrates cell nuclei where it is “read and copied” into mRNA which then acts comparably to the Pfizer and Moderna mRNA vaccines.

Both mRNA and viral vector vaccines have been researched for decades, but…

The mRNA vaccines (Pfizer and Moderna) have never before  been approved for use in any disease.  Source

The viral vector vaccines (J&J) has been used successfully, but only for Ebola.

Because the recent clinical trials only tested the vaccines’ short-run effects … and because the vaccines have limited histories on other diseases … the long-term risks of the vaccines are uncertain.

It is claimed that mRNA is “fragile” and is “eventually destroyed by the cell, leaving no permanent trace” … and that viral vector DNA, while more durable than mRNA, is “rendered harmless (before insertion) and can’t replicate inside them or cause illness”.

If true, to long-term risks are minimal.

But again, the long-term risks are untested and uncertain.

Bottom line: It’s remarkable to have 3 approved vaccines this soon  … thanks to private industry innovation and Operation Warp Speed’s heroic stretch goals, risk-reducing financial supports and reduction of bureaucratic red tape.


FYI: My 1st shot was a Moderna at a retail pharmacy 50 miles from home … selected strictly based on availability.  I would have taken any brand at any location within a couple of hours of driving time.

DISCLAIMER: I’m not a medical professional or scientist — just a curious, self-interested guy.  So, don’t take anything that I say or write as medical advice. Get that from your doctor!

One Response to “J&J is approved … so, which vaccine to choose?”

  1. Vax: “Unexpected things happen when you start fiddling with the innards of living cells.” | The Homa Files Says:

    […] “Which vaccine to choose?” for a summary and links to source […]

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: