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If the COVID-19 Vaccines Work, How Come We Don’t Have Measles and Polio Anymore? And What’s Up With All the Hospitalized Cases?

From the “I’m just asking questions” file in my inbox.

René F. Najera, MPH, DrPH
5 min readFeb 8, 2022

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As the editor of the History of Vaccines, a project by the College of Physicians of Philadelphia, I’m used to getting some interesting emails. Just a few weeks ago, a woman working at the University of North Carolina used her work email to question the fact that children who get chickenpox miss school and could even die. Most recently, someone asked the following question:

“Can someone there please tell me why you say that the COVID vaccines work if people who are getting vaccinated are still getting infected? Do we see people with measles and poliio (sic) who are vaccinated?”

This question has several problems. First, it is an example of the Nirvana Fallacy. That logical fallacy basically states that if something is not 100% safe and effective, then it is not good at all. It is the excuse many people use about the flu vaccine. “Oh, it’s only between 40% and 60% effective, so why bother?” We bother because that kind of reduction in risk is significant. Imagine if half of the people who would otherwise get sick, miss work, use up money to go to the doctor, be hospitalized, or even die, did not have to go through all that. How many resources and productivity would be saved?

The next problem is that it confuses infection with disease. If I get infected with a virus, it means the virus landed on me and began to reproduce. If I have been previously immunized — either by vaccine or disease — then my body has circulating antibodies and specialized cells that will halt the infection much faster than if they had to start from scratch. Many times, they stop the infection so quickly that I have no symptoms.

Once in a while, people who get infected with measles but have been previously immunized still get some symptoms. We call this “modified measles,” and it’s not a mystery. It happens, but those who show these milder symptoms are also less likely to infect others, even if measles is one of the most infectious viruses out there. People with previous immunity to measles — or many other diseases — will, on average, be less infectious…

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René F. Najera, MPH, DrPH

DrPH in Epidemiology. Associate/JHBSPH. Adjunct/GMU. Epidemiologist. Father. Husband. (He/Him/His/El)