Differences Between Pfizer, Moderna and Johnson and Johnson Vaccines

Dr. Cory Harow, an emergency room physician in Boca Raton Florida sees a lot of patients with COVID-19 symptoms. As a consequence, Dr. Harow strongly believes, as most physicians do, that vaccination is the ultimate solution to getting COVID-19 under control within the United States.

He firmly believes in vaccinations for almost everyone, but which vaccine should you choose? Pfizer, Moderna, or Johnson and Johnson? Let’s dwell into the similarities and the differences. I am also fascinated by the process of viral vector manufacturing as it’s just incredible what can be done.

The first major difference has to do with how the vaccines work. This is rather technical, but essentially the Pfizer and the Moderna vaccines work by sending across messages within the RNA in the body.

The two vaccines essentially teach the body to recognize COVID symptoms at a small scale and teach the body to develop an immunity to it.

The Johnson and Johnson vaccine works by introducing a strain of modified and known viruses to spike the body into developing an immunity.

A Difference in the Amount of Shots

Of the three, Johnson and Johnson is the only one that requires only one shot. Both the Pfizer and the Moderna shot require two.

This may make a critical difference in the fight to defeat COVID-19 in favor of Johnson & Johnson.

The reason is that according to the Centers for disease control, 8 percent, or roughly 5 million of those that received the Pfizer or Modera shot have purposely chosen not to take a second shot.

According to the New York times, the reasons vary from those who had symptoms of the first shot, concern about possible side effects from a second vaccine, or feeling protected after getting their first shot.

However, health officials like Cory Harow are very worried about this trend and point out that until people get both shots, they are not considered immune.

Not only is there a greater likelihood that those who do not take a second vaccine dose come down eventually with COVID, but if states or other countries require vaccination before people travel, they may not be considered “officially” vaccinated.


Finally, there is the efficacy of the vaccine. Pfizer, with two doses, is considered 95 percent efficient, while Moderna is 94.1 percent efficient. Johnson & Johnson were initially reported as less efficient, but Johnson and Johnson reported they used different criteria to evaluate the effectiveness of their vaccine. So it’s like comparing apples with oranges.

In addition, Pfizer and Moderna reported their results before new strains were detected of COVID-19. Johnson and Johnson completed its trials during the development of many of the new strains.

What’s in the Future?

Many health experts predict as new strains develop, that people will require an annual booster shot, similar to how many flu vaccines fluctuate.

And just as many people skip getting a flu vaccine, the CDC and health officials will need to ensure people that each new vaccine is safe to take.