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Ciara O'Rourke
By Ciara O'Rourke September 21, 2021

COVID-19 vaccines work, even if they aren’t 100% effective

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  • No vaccine is 100% effective, but evidence shows that the COVID-19 vaccines authorized for use in the United States protect against catching and spreading the virus. Whether everyone will need a booster is still being debated.
 

Reports of vaccinated Americans catching COVID-19 have invigorated vaccine skeptics, but such breakthrough infections are expected, and no vaccine is 100% effective. And that’s not unique to COVID-19 vaccines. 

Still, some Facebook posts have suggested otherwise.

"First in history, a vax that does not prevent catching or spreading a virus, and only lasts for months," one post says. "Mind boggling!"

This post was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook.)

"Vaccines are the best defense we have against infectious disease," the Centers for Disease Control and Prevention says on its website, "but no vaccine is actually 100% safe or effective for everyone because each person’s body reacts to vaccines differently." 

This is as true for the flu vaccine as it is for COVID-19 vaccines.

"Some fully vaccinated people will get sick, and some will even be hospitalized or die from COVID-19," the CDC says. Vaccinated people with breakthrough infections can also spread the disease. 

But most people who get COVID-19 are unvaccinated, and fully vaccinated people who are infected are less likely to suffer a serious illness. Studies show that vaccinated people are eight times less likely to be infected and 25 times less likely to be hospitalized or die from COVID-19 than unvaccinated people, according to the CDC

"Vaccines remain effective in protecting most people from COVID-19 infection and its complications," the agency says. 

All COVID-19 vaccines approved by the World Health Organization for emergency use are required to have an efficacy rate of 50% or greater

As for how long the COVID-19 vaccines provide protection against the disease, if and when everyone will need a booster shot is still being debated. In August, the Food and Drug Administration authorized Pfizer and Moderna to give a third dose of their vaccines to certain immunocompromised people because it could increase protection for people such as organ transplant recipients, Yale Medicine recently noted. In September, an FDA advisory committee recommended booster shots of the Pfizer vaccine for people who receive their second shot at least six months prior and who are 65 and older or have a high risk of a severe case of COVID-19. 

But, again, plenty of other vaccines have boosters. The flu vaccine, of course, is annual, and vaccines against Hepatitis B, whooping cough, chicken pox and measles, among other diseases, require multiple shots. 

We rate this post False.

 

Our Sources

Facebook post, Sept. 19, 2021

Centers for Disease Control and Prevention, Overview, history, and how the safety process works, last updated Sept. 9, 2020

Centers for Disease Control and Prevention, Vaccine effectiveness: How well do flu vaccines work?, last updated Sept. 17, 2021

Centers for Disease Control and Prevention, Recommended child and adolescent immunization schedule for ages 18 years or younger, United States, 2021

Centers for Disease Control and Prevention, Ensuring COVID-19 vaccines work, updated May 10, 2021

Centers for Disease Control and Prevention, Misconceptions about seasonal flu and flu vaccines, updated Aug. 26, 2021

Centers for Disease Control and Prevention, COVID-19 vaccine breakthrough case investigation and reporting, updated Sept. 17, 2021

Centers for Disease Control and Prevention, The possibility of COVID-19 after vaccination: Breakthrough infections, updated Sept. 7, 2021

World Health Organization, Vaccine efficacy, effectiveness and protection, July 14, 2021

Yale Medicine, Will you need a vaccine booster? What we know so far, Sept. 17, 2021

PolitiFact, What are the odds of a breakthrough infection, Sept. 16, 2021

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COVID-19 vaccines work, even if they aren’t 100% effective

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