The FDA and CDC have recommended to halt the use of the Johnson & Johnson (J&J) Covid-19 vaccine “out of an abundance of caution”. They have done so because six cases of blood clots have occurred after over 6.8 million doses of the vaccine had been administered, as of April 12.
The Wall Street Journal notes these are instances of a brain blood clot which is extremely rare in the general population, affecting about 5 people per million per year.
So, how risky is the vaccine?
Since the J&J vaccine was approved in late February, let’s say we are looking at one month of data. Then the incidence of these rare blood clots would be about ten per million per year — double the incidence in the general population. Moreover, all six cases have occurred in women aged 18–48, so the risk for them seems higher. If their share among vaccine recipients is the same as in the general population (20% based on the 2010 census), the incidence of blood clots for women aged 18–48 who received the J&J vaccine would be ten times higher than in the overall population.
But we are talking of an extremely rare form of blood clots, and ten times an extremely tiny risk is still a very tiny risk. Consider the following:
According to the CDC itself, about 900,000 people suffer from blood clots in the US every year. This means the total incidence of blood clots of all kinds in the general population is about 260 times higher than the incidence among people who received the J&J vaccine — and 50 times higher for women age 18–48.
We also know of something else that is responsible for blood clots in women of that same age category: birth control pills, which are linked to an incidence of blood clots of 0.3% to 1% over a ten-year period. This means that a woman taking birth control pills has, in any given month, a risk of blood clots that is between 6 and 19 times higher than from taking the J&J vaccine.
So a similar abundance of caution would suggest taking birth control pills off the market as well. Because it must be the overall risk that matters, not the risk of one specific side effect.
Moreover, we need to look at the risk of taking the vaccine against the risk of not taking it.
As of March 31, just over 23,000 deaths among people aged 18–49 had been attributed to Covid-19 in the US. If we assume about half of them were women, women of that age bracket are over 40 times more likely to die of Covid-19 than to develop blood clots from the vaccine (and so far those six cases have resulted in one fatality, so the risk of death would actually be 240 times higher for Covid-19).
FDA and CDC: you keep using that word, “caution”; I do not think it means what you think it means.
As far as I can make out: (1) a woman age 18–48 is still far more at risk of dying of Covid-19 than of the vaccine — by orders of magnitude; (3) if you are a man, or a woman aged over 48, there is absolutely no evidence that the vaccine poses a risk to you.
Nonetheless, “out of an abundance of caution”, the FDA and CDC have recommended to stop administering the vaccine altogether. President Biden’s Covid Czar said this will not impact the vaccination program, because the Administration has secured enough Pfizer and Moderna doses. But this decision will definitely slow the vaccination progress in the US; this will cause additional avoidable deaths and delay the return to normalcy.
Moreover, Johnson & Johnson has announced that as a consequence it will delay the distribution of its vaccine in Europe; now, Europe definitely does not have enough Pfizer and Moderna doses, so the consequence in terms of additional deaths will be even more serious. Especially since Europe has botched the deployment of the AstraZeneca vaccine in a very similar manner.
The decision to pause use of the Johnson & Johnson vaccine — much like Europe’s earlier decision to pause use of the AstraZeneca — will also increase confusion and fear of the vaccine in the general population. If this ends up delaying the vaccination programs further, the human toll will be even higher.
Scientists should assess whether people with specific risk factors ought to be given a different vaccine; but halting distribution of the J&J vaccine altogether is overkill. Regulators should explain how they assess the overall risk from taking the vaccine, and how it compares to the risk of not taking the vaccine. If we want to bolster confidence rather than fuel anti-vax fears, an abundance of clarity would help a lot more than a vague “abundance of caution”.