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A small number of Americans have been infected with the coronavirus after getting the COVID-19 vaccine. Called “breakthrough cases,” they have been making headlines recently, and they raise a question: What are your chances of getting COVID-19 if you are fully vaccinated?
When it comes to what’s most important – preventing death – the vaccines were 100 percent effective in the trials.
The answer, studies suggest, is very low — probably just a fraction of a percentage point. Still, a few breakthrough cases are inevitable, even with highly effective vaccines.
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"You will see breakthrough infections in any vaccination when you're vaccinating literally tens and tens and tens of millions of people. So in some respects, that's not surprising,” Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said at a March 26 White House COVID-19 briefing.
A Centers for Disease Control and Prevention (CDC) report published on April 2 found that the two-dose COVID-19 vaccine regimen (by Pfizer-BioNTech and Moderna) prevented 90 percent of coronavirus infections two weeks after the second dose, which is when you are considered fully vaccinated. Of the 2,479 vaccinated people in the CDC study, just three had confirmed coronavirus infections after they were fully vaccinated.
Importantly, even if you do get infected after your vaccination, your case is likely to be asymptomatic or mild, like a common cold, says Gregory Poland, an infectious disease physician at the Mayo Clinic in Rochester, Minnesota, and director of Mayo's Vaccine Research Group.
Of the total 9,245 breakthrough cases reported to the CDC as of April 26, 2021, 835 resulted in hospitalization, federal data show. That’s out of more than 95 million Americans who had been vaccinated at that point.
Poland stresses that all three authorized COVID-19 vaccines — from Pfizer-BioNTech, Moderna and Johnson & Johnson — are extraordinarily effective at preventing severe illness: “I've been a vaccinologist for four decades, and I've never seen efficacy like this in first-generation vaccination.”