This week, the CDC and FDA announced that distribution of the Johnson & Johnson COVID vaccine would be put on hold until further investigation could be done into six reported cases of a rare blood clot developing within the first two weeks of getting the vaccine. Seven million doses have been given in the US thus far, so six is a very low number. However, what is concerning is that the type of blood clot is also very rare. It is called a cerebral venous sinus thrombosis (CVST); here the word sinus should not be confused with the sinuses of your nose that can fill up during allergy season. The clot involves the vein that drains the blood back out of the brain as part of its normal circulation. The six people were all women between the ages of 18 and 48. One woman has died while another remains seriously ill according to the New York Times.
A similar problem has been reported in Europe with the AstraZeneca vaccine. Both vaccines use the same technology involving a modified adenovirus to simulate the SARS2/COVID infection, thereby creating an immune response leading to antibody production. In Europe, about 25 million doses of AstraZeneca have been given with a report of 222 blood clot problems. Of these, 169 involved the same CVST while 53 involved a vein draining the abdominal organs, which is also an extremely rare site to develop a clot. Eighteen deaths have been reported. The European Medicines Agency (EMA), which is the European Union’s equivalent to our FDA, has concluded that these unusual blood clots should be listed as very rare side effects of the vaccine, but should not preclude the use of the vaccine as the benefits greatly outweigh the risk.
In Mendocino County, the vast majority of vaccines given thus far have been the Pfizer and Moderna vaccines. These are a totally different technology that does not use a viral substitute, but instead involves mRNA; a discussion of how these work was in last week’s column. A few Johnson & Johnson shots were given, primarily through an outreach program to the homeless. No reactions were reported and we are outside of the two week window when the clots are occurring.
There are huge implications of this worldwide. First, the AstraZeneca vaccine is relatively easy and cheap to manufacture and has the simplest storage requirements. As a result, the World Health Organization has promoted it as the main vaccine being currently used around the world. Another implication is that both AstraZeneca and Johnson & Johnson only require a single dose, instead of two doses like Pfizer and Moderna. This is an advantage for vaccination in certain groups, such as migrant farm workers, where it may be difficult to track a person down to give them the second dose a month later.
Perhaps the biggest implication could be loss of public confidence in the safety of the vaccines. Some people already fear that the safety trials on the vaccines were rushed as part of the Emergency Use Approval process. The investigation by the CDC and FDA will be looking to establish whether or not there is a connection between these unusual clots and the vaccine, however, the EMA has already concluded that there is for AstraZeneca. Following that will be an assessment of the benefit of continuing to use the vaccine weighed against the risks.
It is hard for most of us to appreciate the balance of risk versus benefit of what we do in everyday life. So far, we can say that COVID has killed 562,000 Americans out of a population of 332 million. That is 1.7 deaths out of every 1,000 people or 0.17% of the population. One death from the Johnson & Johnson vaccine out of 7 million shots is a rate of 0.0001 per 1,000 people or 0.00001%. Any treatment has potential negative side effects and a chance of 0.00001% is extremely rare especially compared with the actual COVID death rate which is 10,000 times greater. To help keep this in perspective, perhaps we can consider a real-life risk that most of us face daily. Automobile accidents claim 38,000 American lives each year which is a death rate of 0.12 per 1,000 according to the National Traffic Safety Board (NTSB). An additional 4.4 million people are injured each year due to auto accidents. Yet, we don’t think twice about jumping in the car to drive to work or the store.