In the early days of the pandemic, experts kept a close watch on the number of new cases -- one of the key metrics signaling success or failure of public health measures. But with new variants leading to more frequent breakthrough infections, mild COVID-19 cases will likely still persist, even if every person in the country is fully vaccinated.
"Even before any vaccines were authorized... we knew that this was going to be an issue," said Dr. Lynn Goldman, dean of the George Washington University's Milken Institute of Public Health.
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