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COVID-19 vaccine odds on favorite

We Americans are not good at calculating risk. Some feel that if something bad is going to happen, it will happen to them.

The interpretation of probability varies from person to person and depends on many factors: our emotions, personality traits, experiences and the seriousness of the event of concern.

The odds that something will occur, however, is not a prediction but rather an estimate that something might happen. For example, the odds that you are reading this right now is 1 in 1. The odds of catching a ball while at a major-league ball game is 1 in 563. The odds of fatally slipping in the bath or shower is 1 in 2,232. The odds of being struck by lightning is about 1 in 500,000. We all understand it is unlikely we will catch a baseball, slip and die or be hit by lightning.

Recent news is the Johnson & Johnson vaccine may be associated with an extremely rare but serious condition of a blood clot associated with low platelet counts, also known as thrombosis with thrombocytopenia syndrome.

To date in the United States, more than 200 million COVID-19 vaccines have been given; of these, 8 million are Johnson & Johnson. So far, there have been 15 cases of thrombocytopenia syndrome diagnosed following a Johnson & Johnson vaccine. All cases are in women, 18 to 59 years of age, 6 to 15 days after vaccination. The overall odds of suffering this complication are 1 in 500,000 doses, but for women under 50 years old, the rate is 1 in 140,000.

Just to be absolutely clear, there is no association between mRNA vaccines and these rare thrombocytopenia syndrome events. More than 95 percent of the vaccines given in the United States have been the messenger RNA (mRNA) vaccines of Pfizer and Moderna.

While other countries do not have adequate vaccine supplies, we are fortunate in that we have quantities that allow those who want to be vaccinated to choose among vaccines. We recommend concerned readers discuss with their doctor which vaccine is best for them. It is perfectly reasonable for a young woman to choose a mRNA vaccine to avoid any risk of thrombocytopenia syndrome.

What is not reasonable is to avoid COVID-19 vaccination altogether. COVID-19 is a serious illness. Not surprisingly, thrombocytopenia syndrome has been reported with COVID-19 infections (in women more often than men). Additionally, nearly 9,000 of the 560,000 COVID-19 deaths in the United States have been in women less than 50 years old. Do not forget other risks from COVID-19 such as hospitalization, damage to the heart and lungs and the prolonged fatigue and brain fog following some infections known as “Long-COVID”.

The odds of an aspiring athlete making it into the pros are 1 in 22,000. While that may seem like a long shot, the odds of avoiding SARS-CoV-2 in the long run if unvaccinated are much worse. Vaccination is the odds-on favorite for keeping people safe.

Vaccine Smarts is written by Sealy Institute for Vaccine Sciences faculty members Drs. Megan Berman, an associate professor of internal medicine, and Richard Rupp, a professor of pediatrics at the University of Texas Medical Branch. For questions about vaccines, email

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