How the Johnson & Johnson, Pfizer and Moderna COVID-19 vaccines compare |  ABC27

This post will attempt to answer the following questions:

  1. How do vaccines work?
  2. How does the Johnson & Johnson vaccine work compared to Pfizer and Moderna?
  3. Is it safe?
  4. Is it effective?
  5. Which vaccine should you get?

If a screech of joy could be expressed in text version, this was the sentiment that was given over by my wife’s text after she received her Johnson & Johnson vaccine. Just as everything else with this pandemic, her vaccine experience was annoying, uncertain, and unpredictable. She had heard that the Johnson & Johnson vaccine was available for her eligibility group from a friend and she went searching all over town for a place to get hers. Before embarking on her wild goose chase, she asked me if she should get this shot or wait until an opportunity to get the Pfizer or Moderna vaccines when they are available (and who knows when that will be!?). To be honest, I did not have a clear answer for her as a result of my own ignorance so I got to work doing the research. She decided to get it before I was able to render an opinion but it turns out she made the right choice. I thought I would give you a layman’s explanation of what I discovered and why I think she made the right decision.

How do vaccines work?

Now for a painful oversimplification. Based on the questions I often get, it is clear that many people don’t understand how and why vaccines work. This requires an even more painful oversimplification of the immune response to infection (don’t tell my med school professors who were averse to making anything simple).

The immune system’s response to an infection is dizzyingly complicated, involving billions of interactions between multiple cell types using billions of chemical signals taking place in every part of the body. These billions and billions of processes ramp up in a feed forward loop snowballing until the infection is cleared. Has the word billions made enough of an impact? If not, know that all of those billions of chemicals and cells need time to stimulate each other and ramp up production until the production is adequate to clear the infection. During a real infection, the viruses, bacteria, or fungi, replicate exponentially during this time wreaking havoc until the immune system can catch up. To prevent his time gap in the future, while the immune system is clearing the pathogen, it is also producing special “memory” cells that will remain dormant in the body ready to restart the process if the infectious organism gets back in the body. When the body is re-exposed to the pathogen in the future, these cells ramp up the response without that time delay and clear the infection before it causes disease. There you have it, immunology in a paragraph, please hold the applause.

The goal of all vaccines is to get one or more parts of the organism into the body in a way that is harmless. These parts will then stimulate an immune response without having to expose the body to the actual live organism. The parts are recognized by your immune system which stores this recognition in memory cells. This way, you get the memory response without the initial infection. What a bargain!

The goal of all vaccines is to get one or more parts of the organism into the body in a way that is harmless.

As an aside, since the immune response to an organism is responsible for the symptoms of an infection. It is also the reason for the common vaccine side effects. If you have a sore arm and feel crummy after a vaccine this is a sign that it is working. Three cheers for feeling crummy!

How the J&J vaccine works:

The J&J vaccine was actually developed by the pharmaceutical company Janssen which is a subsidiary of Johnson & Johnson. Perhaps it should be called the J&J&J vaccine. Either way, you may hear it referred to either way in the media. The means by which vaccines get into the body differs depending on the vaccine. The Pfizer and Moderna vaccines work by getting a piece of the SARS-CoV2 mRNA into your muscle cells which then starts making this protein triggering the immune response.

For the J3 vaccine (I’ll take credit for this new nickname), the pieces of the surface binding protein of SARS-CoV2 ware inserted into an adenovirus. The virus was modified so that it cannot replicate in the human body so it cannot make you sick.  Janssen inserted the RNA for the SARS-CoV2 spike protein into the weakened adenovirus DNA. This creates an adenovirus that makes the SARS-CoV2 spike protein. Since it is only making one part of the SARS-CoV2 virus it cannot cause COVID-19. (I have to bold and italicize for emphasis to protect you from social media lunatics and idiots). After a person receives their shot, the body will temporarily make the spike protein (again, this does not cause disease). This triggers the immune system to produce an response against SARS-CoV-2. This includes producing the cells that are responsible for the memory response.

Image description not available.
Source: JAMA, Marcy 2020; doi:10.1001/jama.2021.2927

Perhaps this metaphor will help. Imagine you took your kids Little Tykes car, you know the kind that are orange and yellow and fit one kid at a time.

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Now take the hood ornament from a Mercedes and glue it to the front of the toy car. This toy car is harmless. You would let your kid drive it. You would not think he was driving a Mercedes. Actually, maybe you should use a Honda ornament so he doesn’t get spoiled. Regardless, he now knows how to recognize a Mercedes or Honda in the future. So the weakened adenovirus (the Little Tykes car in the metaphor) carries a harmless piece of the virus (the ornament) that identifies it to the outside world, but it isn’t actually in any way close to being a Mercedes.

Is it safe?

The most important thing for all vaccine trials is safety and no drugs or vaccines in history have ever been under the level of scrutiny for safety issues by the world’s regulatory agencies, public health institutions, and general public as these vaccines. In the main randomized controlled trial, the most commonly reported side effects were pain at the injection site, headache, fatigue, muscle aches and nausea. Most of these side effects were mild to moderate in severity and lasted 1-2 days. There were no serious side effects reported that were more frequent than in the placebo group. Safety monitoring will continue as people get vaccinated in the real world but the risks of the vaccine are certainly less than the risks of the virus.

What is the efficacy?

As was mentioned in our discussion of the Pfizer vaccine, efficacy is how well the vaccine does in the research trial while effectiveness is how well it does in real life. The way efficacy is measured is by counting up the number of moderate to severe infections, hospitalizations, and deaths in the vaccine group and in the placebo group and determining the relative difference between those two fractions. If there’s no difference between the vaccine and placebo groups, the efficacy is zero. If all the infections are in the placebo group without any occurring in the vaccine group, the efficacy is 100%.

Overall, the vaccine was approximately 67% effective in preventing moderate to severe/critical COVID-19 occurring at least 14 days after vaccination and 66% effective in preventing moderate to severe/critical COVID-19 occurring at least 28 days after vaccination. 

Isn’t that bad?

No. For a lot of reasons.

The vaccine had 100% efficacy at preventing deaths or hospitalizations.

It was perfect in the ways that really matter for the pandemic. Even though this vaccine was not as good at preventing symptomatic infection as Pfizer or Moderna’s, it was 85% protective against severe disease, with no differences across the eight countries or three regions in the study, nor across age groups among trial participants. Severe in the trial did not include those who were hospitalized, they were ae separate category. For this metric, there were zero hospitalizations or deaths in the vaccine arm of the trial after the 28-day period in which immunity developed. In other words, the vaccine had 100% efficacy at preventing deaths or hospitalizations. So if you worry about getting very sick or dying, all three vaccines are equal. If everyone in the world got this vaccine COVID would be a common cold and I would be having a big party.

The variants need to be accounted for. The research trials were done in multiple locations around the world and at different times during the pandemic. This can have a major impact on the results in a rapidly evolving pandemic with new viral variants. A large portion of the J&J trial was done in South Africa where the B.1357 strain has shown mutations that make it resistant to vaccines. There was also a significant number of patients from Brazil which has the concerning P.1 variant which also may impact vaccine efficacy. These variants were not around in significant numbers or in the locations of the Pfizer and Moderna trials. It is therefore reasonable to believe that, had the J&J trial been done earlier and in other countries, it may have had efficacy rates similar to Moderna and Pfizer. The converse would then also be true; Moderna/Pfizer efficacy would be lower if it was tested in Brazil and South Africa. In fact, the efficacy was higher in the United States for the Jx3 (choose the name you prefer) vaccine where there weren’t these variants.

This also is good news with respect to the variants. The vaccine was still very effective, even when accounting for the new variants.

These numbers are still very good. As a comparison, the flu vaccine is considered to be not bad and it has an effectiveness (not efficacy) of 40­–60% but research has shown that in 2019-19 the flu shot prevented around 4.4 million illnesses, 58,000 influenza-associated hospitalizations, and 3,500 influenza-associated deaths. So the flu shot is a good vaccine. This means the J3 is a very good vaccine.

Logistics could skew the numbers. The Moderna and Pfizer vaccines require two doses and must be stored at very low temperatures. If there is a problem with the cold storage the vaccines will not be as effective. Since the research setting is much more controlled than real life it is very reasonable to think that the effectiveness will be less than the efficacy. Since the J&J vaccine is a one shot dose and stable in a refrigerator this is less of a concern.

What about preventing asymptomatic infection

If you check out my post, The Best Possible News, I explained the data from Israel showing how the Pfizer vaccine prevented asymptomatic infection which has huge implications for lockdowns and mitigation policy. There is preliminary data for J&J that it was 74% effective at preventing asymptomatic infection. They did this by checking antibody levels in the vaccine and placebo group and seeing how many people had a positive antibody test without ever having symptoms.

So which vaccine should you get?

You should get whichever vaccine you are offered first.

Based on the above information and the information I put forth in prior posts about the mRNA vaccines, this is an easy question to answer. You should get whichever vaccine you are offered first. It’s as simple as that. They are all wonders of modern science so dazzling that it boggles the mind. We have become a bit used to the efficacy numbers and have lost in the noise how amazing they are. I think all COVID-19 vaccine developers should split a nobel prize. For all the errors and missteps in the pandemic, it should be emphasized that the only way we are able to see the light at the end of the tunnel is because of the herculean worldwide efforts of brilliant people in the scientific community. Most of them are smart enough to get jobs that pay much more than their usually dismal salaries but, instead of chasing the dollars, they dedicate themselves tirelessly to the pursuit of knowledge and bettering our lives. Show them your respect and adulation by convincing everyone you know to get their vaccine and, when the shot goes in your arm, thank God and thank them (sending those post to your friends would honor them also).


2 thoughts on “Is the Johnson and Johnson vaccine any good?

  1. Thanks for your amazing and informative posts! I am a healthcare worker and BH received 2 doses of the Pfizer vaccine. My husband is a teacher and got the J&J (or J3!). My second dose was a day after his one and only. Here’s my question: is there a difference in how quickly we’re both at “full protection”? I’ve ready that it takes up to 2 weeks following the second dose of Pfizer/Moderna. Is the same true for the J3, full immunity benefits will not be seen for up to 2 weeks? Can you explain this a little?


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