Johnson & Johnson: Blood Clots and a Media-Made Boogeyman

Let’s talk vaccine. Specifically, let’s talk about Johnson & Johnson: blood clots, FDA-ordered pausing, and safety clearance.

Now, being a science communicator, I’ve received a lot of messages about this. A lot. And while I could wax poetic on a borderline opinion-based tangent, I think that situations of this nature – surrounding adverse events – deserve objectivity. After all, you’re here for science. So science is what I shall give you.

Johnson & Johnson: Blood Clot Background

In a period from late March to early April, six cases were reported to the Vaccine Adverse Events Reporting System. These cases were all women, between the ages of 18 and 48, who developed a type of rare blood clot, shortly after receiving the Johnson & Johnson vaccine (i.e., within 13 days of vaccine administration). This type of blood clot is called a “cerebral venous sinus thrombosis”. To break this down: a blood clot is a little gluey chunk of blood that may get lodged in your vessels, and can subsequently impede blood flow. While these can be dangerous if found anywhere in the human body, when they appear in the venous sinuses of the brain, they can obstruct cerebrospinal fluid flow, contribute to increased pressure inside of the skull, and may ultimately contribute to conditions which lead to death (tragically, one of the six women did lose her life).

On April 13, 2021 the FDA requested a pause of the administration of the Johnson & Johnson vaccine to investigate the rare complication. During the time of the pause, one additional woman was reported with the same blood clot.

This brings the reported cases of cerebral venous sinus thrombosis events, in women, to 7. Out of 6.8 million vaccines administered.

This is a 0.000103% incidence rate.

By comparison, the rate of venous blood clots reported from oral birth control is approximately 0.03 -0.05%, annually (Hannaford, et al., 2000).

On April 23, 2021 the FDA lifted the pause on the vaccine and allowed administration to continue.

Johnson & Johnson: The Vaccine

The Johnson & Johnson vaccine confers immune response in a way that is a bit different than Pfizer and Moderna. Both types of vaccines help to teach the body to recognize SARS-CoV-2 (the virus that causes COVID) spike proteins. While Pfizer and Moderna deliver this biochemical message by an mRNA template encased in an inert bubble, the Johnson & Johnson vaccine actually delivers this message with a carrier virus (in this case, a little adenovirus that has been stripped of its molecular malice and has had its infectious abilities removed). So, same endgame with a slightly different method of getting there.

The benefit of Johnson & Johnson is that it can be administered in a single dose, which increases the ability to widely vaccinate a larger swath of the public and theoretically reach a point of herd immunity with more ease, faster.

 The COVID-19 Virus: Clotting Contributor

It has now been widely established that contracting COVID-19, itself, makes patients more susceptible to developing blood clots. In fact, some reports suggest that up to 20% of those who are admitted to the ICU with COVID-19 may present with this clotting issue – a figure much higher than ICU admittance for other ailments. Rigorous studies suggest that this is due to damage that the virus (or inflammation caused by the viral infection) does to the layer of cells that lines the inside of blood vessels (Biswas, et al., 2021).

Johnson & Johnson: Administration Begins Again

With Johnson & Johnson now cleared for re-administration by the FDA, many people wonder if the vaccine is actually safe. However, to remind the reader (and as currently suggested by experts in the field of infectious disease) the risk of developing these particular side effects is incredibly rare (one-ten-thousandth of a percent), while the risk of developing venous blood clots from actually contracting the virus, itself, is much higher (to say nothing of the myriad of other, nasty viral side effects).

So, think critically, dear reader. Read with a keen eye. Ask questions. Trust the teams of thousands of scientists and experts.