The Claim:
A common anti-vaccine trope is that diseases were on their way out before any vaccines were licensed; therefore, vaccines do not have any effect on disease. This anti-vaxxer’s recent tweet about measles is an example.
The Facts:
Measles is one of the most transmissible infections in humans. One infected person can infect 12-18 others in a group of susceptible people. Prior to vaccines, it was expected that nearly everybody would get measles at some point in their life, usually during childhood. If the measles vaccine conferred no immunity, as the tweeter suggests, measles would still be circulating freely. Instead, almost no one gets measles anymore.
Yes, measles mortality did decline before the introduction of the measles vaccine due to better medical treatments. Measles cases, however, did not decline until after vaccination began. And while people may not have died acutely at the same rates as they did, measles can also lead to blindness, deafness, and SSPE, a type of brain disorder that leads to death years after the initial infection.
This common trope relies on confusing death (mortality) and illness (morbidity). Medical advances slowed down the death rate from measles, but vaccines stopped it.
Disclaimer: Science is always evolving and our understanding of these topics may have evolved too since this was originally posted. Be sure to check out our most recent posts and browse the latest Just the Facts Topics for the latest.
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