What’s Up with the J&J Vaccine? A Doctor’s Q&A

The J&J COVID vaccine’s possible link to blood clots is dominating the news, creating disproportionate fear and confusion. Let’s tackle the most pressing questions:

Q1. As a pro-vaccine advocate, are you mad at the CDC/FPA for pausing the J&J vaccination?

Absolutely not! The very fact that we are hitting “pause” on distributing this vaccine based on 6 cases (less than 1 in a million vaccine recipients) of a very rare problem should honestly be extremely reassuring to everyone concerned about vaccine safety. The very reason we HAVE vaccine adverse events reporting systems in place is to pick up ANY and EVERYTHING that might possibly be an adverse result of vaccines.


Q2. How common are these “brain blood clots” in the general public WITHOUT getting a COVID vaccine, and how does that compare with what is being seen with J&J vaccine?

Cerebral Venous Sinus Thrombosis (CVST) is indeed a rare event, occurring in an estimated 2-4 per million adults per year. There have been 6 reported cases of women aged 18-48  (slightly less than 1 per million) who received the J&J COVID vaccine 6-13 days prior to being diagnosed with a CVST.


Q3. What typically causes these rare brain blood clots?

As with many rare medical problems, there is not a simple answer, but risk factors for CVST include hormonal changes (birth control pills, pregnancy, and shortly after giving birth), infections, trauma/surgery, cancer, inflammatory diseases, certain drugs, and blood or neurological disorders. One study on CVST showed that 85% of women with this rare CVST were taking birth control pills (34 of 40) vs. only 45% of the women in the control group who did not develop CVST. [de Bruijn et al.] However, infection, trauma, cancers, inflammatory diseases, dehydration and certain drugs can play a role, and frequently multiple factors contribute. We do know that 85% of adults with this problem (CVST) have at least one identifiable risk factor. (Any specific risks of the six women with CVST after their J&J vaccine have not been publicly shared yet.)


Q4. So, if birth control pills can cause clots, why aren’t we taking THEM off the market?

Every medication, surgical treatment and yes, vaccine, has SOME inherent risk. Over-the-counter products like aspirin, Tylenol or Advil are no exception- take a look at the fine print! We all KNOW these risks, but we make a choice that the benefit (pain relief in this example) outweighs any small risk. Back to oral contraceptives: when physicians initially prescribe birth control pills, we discuss potential adverse side effects, including the fact that birth control pills do increase your risk of developing a blood clot by roughly 3-fold. However, we also give perspective by explaining the likelihood of developing a blood clot.

  • 1 to 5 of 10,000 healthy, nonpregnant women will develop a blood clot.
  • 3 to 9 of 10,000 healthy women taking estrogen-containing oral contraceptive pills will develop a blood clot.
  • 5 to 20 of 10,000 healthy pregnant women will develop a blood clot.

We  obviously also discuss the benefits, such as improving acne, painful menstrual cramps or heavy periods, and the obvious, preventing pregnancy. If you’d like to read more, click HERE to see an excerpt from The ULTIMATE College Student Health Handbook: Your Guide for Everything from Hangovers to Homesickness.  

The worse the problem (think cancer), the more side effects (chemo) we are willing to accept in our risk/benefit analysis, and our decisions are often based on our personal experiences (say, your aunt dying at age 40 of breast cancer.) With over 550,000 American deaths from COVID19, many of us have lost friends, family or patients, and obviously this shapes our bias regarding vaccines.


Q5. If these clots are occurring at a lower rate than we would expect to see in the “normal” population, why is everyone jumping on this and halting the vaccine?

Obviously with the COVID vaccines, any answer here is (sadly) affected by more than science. Politics, legal climate and public opinion all weigh in, and I have no magic wand to remove them. However, scientifically, I believe the pause is fully legitimate for a few reasons.

  • CVST is RARE, so many physicians have never seen a single case. Although I have never had a patient with this particular blood clot myself, I have been aware of at least three such cases seen by local colleagues in the last decade. Whenever we see something rare, we routinely SHARE this information with other doctors. Doctors learn a zillion rare diseases that we try to keep in the back of our brains, so we never miss a diagnosis. We have a saying- when you hear hooves, think horse, not zebra…but we still have to consider the possibility of that zebra. If you never consider a zebra, you will never diagnose one. Especially because CVST is treated differently than standard blood clots, this pause is helping doctors be better prepared to both diagnose and treat this rare problem.
  • Scientists were already investigating rare cases of CVST with low platelets in patients who had received the Astra Zeneca vaccine in Europe, and since the J&J vaccine has a similar delivery system (the shell of a cold virus), it makes sense to look closer when we see even a few cases with the same unusual pattern. Note that there MUST be additional individual contributing factors involved, because it bears repeating that this has been seen in less than 1 person per million in the US, and roughly 4 per million in the UK (with AZ vaccine.)
  • We do have other OPTIONS while scientists investigate further. The mRNA vaccines (Pfizer and Moderna) have been given to over 116 million Americans with no such red flags.


Q6. I heard COVID19 can cause this same type of rare blood clot, is that true?

Yes, we have known for over a year that COVID19 causes blood clotting problems that complicate the severely ill patients. One study published today that evaluated hospital records of over 500,000 patients admitted with COVID 19, shows the risk of developing a cerebral venous thrombosis (CVT/brain blood clot) was 100 times greater than the general population, and 10 times greater than those who had received vaccines. (“CVT in all patient groups was rare, at 39 per 1 million COVID-19 patients and 4 in 1 million vaccine recipients.”)

Q7. What should I do if I got the Johnson & Johnson vaccine last week? Should I stop my birth control pill since that can cause clots, too? How worried should I be?

Full disclosure, our younger daughter is in this category, as she received her J&J vaccine on April 7th, so I am by no means a disinterested third party! My honest answer is that primarily, you should relax and feel confident you are building antibodies to protect your body from COVID. Obviously, you should pay attention and seek immediate medical care if you were to develop a severe headache, seizures, or severe leg or abdominal pain- which I would hope you would do regardless. If you are feeling anxious, do your best to have perspective that you are likely not spending time worried about more common problems like getting in a car accident (very common) or being struck by lightning (rare, but occurs twice as often as the CVST noted after J&J vaccine). There is no evidence to suggest stopping your birth control (remember pregnancy carries far greater risks of clotting, among other things!) Know that more women than men have received the COVID vaccines, and from national statistics, we can safely assume that a huge percentage of those women are on birth control, too.

Q8. Anything else the public should know?

I would like to clarify something about our Vaccine Adverse Events Reporting System (VAERS.) Vaccine skeptics often point to the numbers of deaths or severe problems reported for a given vaccine, without acknowledging that these cases reported do not all have proof of causality from the vaccine. Here is how VAERS works. If you come to my office and we give you a Tetanus or flu shot, and then on the way home you are in a terrible car accident and die, we can and really should report that death to VAERS. Why? Obviously, the shot didn’t cause your death. BUT- especially with a NEW vaccine- we want to cast a wide net to catch any and every possible bad reaction. What if a new vaccine is causing people to faint, and that fainting is occurring in the hour after the vaccine as they are driving? Well, that would cause car wrecks, which would be the fault of the vaccine. We report EVERYTHING, then the data-analyzing scientists look for statistically significant patterns that suggest cause/effect. So, if you dive deep into VAERS, you will see causes of death that range from drug overdose to car accidents to cancers. And speaking of cancers, when we have, for example, a rare childhood cancer that occurs in one out of every million kids/year, at some point we will end up seeing that cancer appear in proximity to a routine vaccination.

Q9. If/when they stop the pause on J&J, which COVID vaccine should I get?

My answer remains that you should get whichever COVID vaccine you are offered first, although I will not be surprised if the J&J is initially reinstated with some gender or age restrictions. Our family sampled all three- hubby and older daughter got Pfizer, I got Moderna, and our younger daughter had J&J last week. If I had to choose, I’ll confess that I’ve got a bit of a crush on Moderna. Why? Partly because I’ve personally administered well over 1000 doses and I LOVE how it doesn’t burn or sting, so many people rave that they never felt the shot! But more because my inner science geek is in AWE of the mRNA technology, and I love how “clean” the shot is because with our cells doing the work to create the spike protein, there is no need for extra ingredients or preservatives. Pfizer is equally wonderful, though, and people often experience fewer immune response symptoms after the second dose. Truth be told, however, I shed happy tears when our youngest got the Johnson and Johnson, because she was “one and done”!

BOTTOM LINE: Science FIRST! Be reassured, not alarmed, from the pause on the Johnson & Johnson vaccine. I hope we can all agree that COVID is our common enemy, and I believe our COVID vaccines are the most important, safe, and effective way to move past this pandemic.  



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