Wednesday, May 5, 2021

Pro-vaxxers not following the science, either

COVID Vax Opponents and Rigid Proponents...Are Both Anti-Science? | MedPage Today -  Vinay Prasad, MD:

May 4, 2021 - "In mid-April, vaccine scientists and regulators were alerted to six serious adverse events after administration of the Johnson & Johnson COVID-19 vaccine ... in women ages 18 to 48 ... similar to reports from Europe regarding the other adenoviral-based vaccine made by AstraZeneca. The syndrome is best described as vaccine-induced thrombocytopenia and thrombosis (VITT).... 

"VITT can result in death, but also, serious and irreversible neurological impairment in an otherwise young healthy individual. After the FDA and CDC were alerted to these six cases, the agencies called for a pause or moratorium to be placed on use of the J&J shot pending further review. A few days later, a panel of experts extended the pause by 1 week, during which time at least nine additional cases of the syndrome were identified. After a hearing to discuss the risk and benefit, the Advisory Committee of Immunology Practices (ACIP) voted to resume vaccination with J&J without any restrictions by age or gender, though they recommended placing a warning....

"The moment six cases were publicly reported and the pause was instituted, a large number of experts expressed anger on social media. They claimed the denominator was the seven million doses of the vaccine that had been administered, and this event rate -- less than one in a million -- was a trivial safety signal. Some were critical of the pause itself -- which I will discuss in the next section -- while others worked to immediately downplay concerns of the risk. A popular series of memes compared the risk of CVT and VITT to the risk of thrombosis from other events. One compared VITT to the risk of clot with oral contraception and thrombosis after COVID-19. These went viral (no pun intended).

"Unfortunately, these comparisons perpetuated at least five errors.

  • First, one in a million was almost surely the wrong number. The moment a novel safety signal is identified, preliminary estimates of frequency are utterly unreliable.... There are likely more unreported cases, which will raise the numerator, and the denominator should not include all vaccinated individuals. The correct denominator is the fraction of vaccinated individuals in the demographic group experiencing the severe event -- in this case, women ages 18 to 48. I tweeted that I would not be surprised if the true incidence jumped one order of magnitude when we had more facts -- a prediction that has since been vindicated.
  • Second, comparing the risk of CVT in the setting of VITT to a garden variety venous thromboembolism is misleading. A deep vein thrombosis of the leg is not comparable to one in the cerebral vein in the setting of runaway platelet activation. I have long wondered how much anatomy should be taught in medical school, but I can now confidently say we should definitely clarify the difference between veins that drain the brain and those that drain the leg.
  • Third, comparing the risk of CVT and VITT after vaccination to the risk of clot after COVID-19 is inappropriate. Getting COVID-19 and getting vaccinated are different. A vaccine's risk cannot be changed, while the risk of COVID-19 can be altered or modified by behavior. In fact, the bulk of this past year has been making behavior changes to modify SARS-CoV-2 risk.
  • Fourth, some numbers are simply wrong. A 16.5% risk of clot among someone with COVID-19 is an inflated figure that, as far as I can tell, comes from meta-analyses of ICU patients in the first wave. These analyses likely suffer from selection, surveillance, and ascertainment bias, among other problems.
  • Fifth, comparing the risk of CVT and VITT to oral contraception was objectionable.... [I]nformation about the risk of clot is available before women start taking the pill and they can balance this against their other desires. With CVT and VITT, women did not know the precise risk, still don't know exactly, and these folks were essentially arguing against providing women that information.

"The first crux of the public communication failure is to ask why, when we hear of a novel adverse event, is the reaction of so many experts to downplay or trivialize the risk? Why construct minimizing memes when you have not even gathered all the relevant facts? The answer to this question warrants reflection, but I will offer a hypothesis. 

"In 2021, there is clearly a small, but vocal minority of individuals opposed to nearly all vaccinations.... In response, there is a group of individuals on the other extreme. To them, either one must embrace all vaccines for all indications for all ages, or one can be lumped with the other extreme. They favor universal child vaccination of SARS-CoV-2 via an EUA, even before they have the data for that claim. They were quick to embrace vaccination for pregnant woman prior to appropriate trials establishing safety. Suppressing critical thinking to extol vaccines is also wrong and may backfire, but I believe this explains why it occurs. It is, to some degree, a counter-movement against the anti-vaxxers, which can go too far.

"All of this discussion is not a referendum on the pause, which must be considered on its own merits.... [W]hether the FDA and CDC should have issued a total pause for J&J vaccine ... cannot be settled by rhetoric. It requires careful studies. Pauses have complex downstream effects. Yes, they may poison vaccine acceptance. On the other hand, inaction, while the tally of women with CVT and VITT rises, is also a dangerous game."

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