One Hundred Percent

There is a scene in Zero Dark Thirty, the film about the raid that killed Osama Bin Laden, in which a group of CIA agents is pondering whether Osama is  hiding in a certain house in Islamabad.   The CIA Director asks around the table for opinions about how certain each of the senior agents (all men) are that it is indeed Osama.   Each of them offers a cautious estimate of the likelihood on the order of 60%.  Maya, the agent who gathered all the intelligence, becomes increasingly agitated with each estimate.   Finally, the director turns to her and says, And what do you think?  Without hesitation, she says, One hundred percent.  Then, gauging their reaction, she says, OK.  Ninety-five percent.  I know certainty freaks you guys out.  But it’s him.   In my line of business, we are often trying to find a very weak signal (say, an object of interest to a radar) surrounded by other objects we don’t care about.   The likelihood that we detect the target is known as the probability of detection and our customers would love that to be 100%.   Many times we are lucky to give them 50%.

This all occurred to me this morning as I was reading the concerns about the Johnson and Johnson COVID vaccine causing potentially fatal blood clots.   According to the New York Times, On Tuesday morning, U.S. federal health regulators recommended a pause in the use of Johnson & Johnson’s Covid-19 vaccine while they investigated six reports of blood clots in women ages 18 to 48.   One has died, and a second is hospitalized in critical condition.  On Wednesday, two more cases were added to the list: a seventh woman who received the vaccine after it was authorized, and a man who received it during a clinical trial.  As of Thursday, 7.4 million people in the United States had received the vaccine without any other serious adverse reactions reported.  Now, to put that in context that is about a .0001% chance of a blood clot or, in terms of my examples above, a 99.99% likelihood of NOT having an adverse reaction.  My customers would kill for a 99.99% detection rate.

So what you probably want to know is What are the chances of dying from COVID without a vaccine compared to the chances of dying from a clot due to the J&J vaccine.   I found a very rough calculation** by age group on News Center Maine yielding this table:

                     chart courtesy News Center Maine

This chart isn’t quite what I’d want to know … the likelihood of dying from COVID without a shot vs. the odds of dying from COVID or a blood clot with the J&J vaccine.  Continuing the sloppy statistics, let’s assume that the vaccine is 95% effective, so the chances of dying with the vaccine is about 1/20 of column 2.   What that means is that the chances of dying from a blood clot is negligible compared to that of dying from COVID period, except for the youngest age groups.  SO.  While it makes sense for the CDC to carefully examine what’s going on with the J&J vaccine, the news should not deter you from being vaccinated.   The virus is definitely more deadly.

** This whole analysis would embarrass my statistics professor, Dr. Harris, potentially risking the revocation of my degree.   It would take another post of equal length to discuss why it is very approximate … which would likely eliminate the last of my few readers.  So, the take away is the message, not the math … VACCINATE.

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Tags: COVID-19, health, senior health, statistics, Vaccinate!!

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