Pausing the J&J Vaccine is Wise- Here’s Why:
I wanted to post my take on why pausing the J&J vaccine is wise, along with pausing the AstraZeneca vaccine.
Also, if you prefer you can watch the video version on my Youtube channel here.
I get creative with plates, construction paper and tennis balls… Ahem. You can also watch it on my Instagram channel here.
So what happened?
The FDA and CDC just announced that they are pausing the roll out of the Johnson & Johnson vaccine due to the formation of blood clots. They are following the steps of several regulatory bodies across Europe who paused the use of AstraZeneca’s vaccine because of blood clots.
First, what do the Johnson & Johnson and AstraZeneca vaccines have in common?
They are both viral-vector vaccines. This means a common virus is made harmless by removing the genes that allow it to replicate and cause disease. It is turned into a vector, or a vehicle for delivering information to our bodies. Researchers insert the genetic code for something called the Spike Protein on COVID-19 into the viral vector. (The Spike Protein is what allows COVID-19 to stick to our cells and infect them.)
The viral vector travels to our cells and delivers the code for the Spike Protein. Our cells read the code, make the Spike Protein and present it to our immune system. Our immune system responds by making protective cells. If in the future a vaccinated person is exposed to the actual COVID-19 virus, his/her immune system will recognize the Spike Protein and have cells ready to respond and keep you from getting sick.
What are these harmless viruses that are used as vectors?
Both Johnson & Johnson and AstraZeneca use adenoviruses, but Johnson & Johnson uses a human adenovirus (Ad26) and AstraZeneca uses a chimpanzee adenovirus (ChAdOx1). ( Russia’s vaccine, Sputnik V, is also a viral-vector vaccine that uses Ad26 and Ad5.)
What’s going on with the blood clots?
It’s important to remember that, right now, the blood clots linked to both vaccines are very rare. Many people have received either vaccine and are completely fine. But in some cases, cerebral venous thrombi, or clots in the brain, have formed. I’m not sure about Johnson and Johnson yet, but the AstraZeneca vaccine has also been linked to clots in the splanchnic vein and lungs. Some folks are comparing this clot formation to the clots we sometimes see with birth control pills.That’s not a good analogy. The location of the clots is different and, in the case of the vaccines, no underlying risk factors (like smoking) have been identified.
What’s causing it?
In short, they don’t know exactly. Dr. Greinacher and his team in Germany have identified a possible mechanism of action. In the cases they studied, everyone had antibodies against something called PF4, or platelet factor 4. These antibody-complexes will ultimately bind to a receptor on the platelets ( called the FC receptor) and activate them. When platelets are activated, they form clots.
A similar mechanism is seen in some people who take Heparin, a common anti-clotting drug. What happens is heparin ( a negatively charged molecule) binds to Platelet Factor 4 (PF4) (a positively charged molecule). Next, an antibody forms and binds the PF4-Heparin, forming an immune complex. The immune complex needs to “park” somewhere, so it pulls into a “parking slot” ( the FC receptor) on the platelets. From this point, two things can happen. The platelets can be removed by cells called macrophages OR they can be activated and form clots. Please watch my Youtube video for a visual of this!
When do symptoms occur?
Symptom onset is 4-16 days after vaccination. They include severe headache, severe abdominal pain, severe leg pain and shortness of breath.
Who is affected?
In the case of both vaccines, otherwise healthy, young(er) women under 50, are the most affected. In a case report out of Germany, women between the ages of 22-49 ( average age of 36) were affected. The CDC reports that women between the ages of 18-48 were affected.
Why is that important?
It’s important, because it’s a healthy and relatively young age group, and when it comes to COVID-19, the risk/benefit analysis for this group is much different than the one for old(er) people, who are at a much higher risk of dying from COVID-19.
Why is it wise to pause the vaccine?
It’s wise to pause the J&J vaccine for the following reasons:
- Unlike a lot of medication, vaccines are given to otherwise healthy people with the goal of protecting them from future illness. That is why they need to be as safe as possible. When you see a serious, though rare, reaction in a young(er) population that is at a much lower risk of dying from the illness you are vaccinating against, you need to pause and figure out what’s causing the serious adverse reaction.
- Pausing shows that regulatory bodies are doing their job. Research shows that people who are most vaccine hesitant are most concerned about vaccine safety. I truly believe that in the long run, regulatory bodies taking these reactions seriously will help build confidence in future vaccines. If they don’t, it won’t.
- These vaccines are new and data is still being collected. While they seem safe for the majority of the population, they may not be for certain smaller subgroups. Now is the time to figure out who those subgroups are. If not now, when?
- There is no question that boosters are in our future. There is no question that vaccinating children, no matter how you feel about that, is in our future. Since this side effect is so severe and happening in younger people, we need to figure out why and who is at risk before we begin using it on kids.
- The pause gives us time to identify risk factors, identify at-risk groups, alert and educate healthcare providers about this side effect and, most importantly, present the best prevention and treatment approaches. For example, you may want to limit these vaccines to certain ages. Or you may not want to give Heparin when treating it, because it might make things worse. You might want to give a different anticoagulant medication or a different antibody that could park in the “FC receptor” spot, thereby preventing the “bad” antibodies from doing it and triggering clots. Also, alerting healthcare providers about the timeframe of this reaction may save lives and give us more accurate data. Given the 3-week window for clot formation, some providers may not associate a clot with a vaccine given 3 weeks prior, which risks those cases not being reported as side effects.
You got the J&J or AstraZeneca vaccine, should you worry?
Again, I can’t stress this enough: This is a rare event. When I sat in on a Zoom press conference with Dr. Greinacher, he kept stressing that it was a rare event. Millions of people will get the vaccine and be fine. However, if you experience any of the above-mentioned symptoms in the 3-week window after being vaccinated with one of these vaccines, you may want to seek medical attention.
Getting Vaccinated is a Personal Choice.
I understand how important autonomy is when it comes to making decisions about your health. I respect your ability to do your own risk vs. benefits analysis and do what’s right for you.(I’d want the same for me.) My only advice is to make sure you get accurate information from trusted sources when doing that risks vs benefits analysis. If you choose to get vaccinated but are concerned about clots from the viral-vector vaccines, you can get one of the mRNA vaccines instead. Those include Pfizer and Moderna.
I hope this was helpful. In conclusion, pausing the J&J Vaccine was the wise and ethical thing to do.
(Erin Stair, MD, MPH)
Opinions are my own and don’t reflect anyone I work for/contract with