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