The U.S. Centers for Disease Control and Prevention has identified a small cohort of approximately 5,800 cases of Covid-19 infection among more than 66 million Americans who have completed a full course of vaccination.
These so-called breakthrough cases, defined as positive Covid-19 test results received at least two weeks after patients received their last vaccine dose, represent 0.008% of the fully vaccinated population.
Officials said such cases are in line with expectations because the approved vaccines in the US are highly effective, but not 100% foolproof. They remind us that even vaccinated people are at risk and must continue to take precautions in many circumstances, such as masking and social distancing.
Earlier this year, the CDC asked state health departments to track down breakthrough cases and report them to the federal government. The cases reported so far have come from about 40 states.
Separately, The Wall Street Journal contacted health departments in all 50 states and the District of Columbia to ask how many breakthrough cases had been identified. Twenty-three states responded and reported a total of 4,172 breakthrough cases.