Update of the best US study on vaccine effectiveness in the "real world" (vs clinical trial), initially published by the CDC in April. Summary: https://www.cdc.gov/mmwr/volumes/70/wr/mm7034e4.htm Full paper: https://www.cdc.gov/mmwr/volumes/70/wr/pdfs/mm7034e4-H.pdf   They studied vaccinated and unvaccinated health care workers - first responders, healthcare workers, and other patient-facing essential workers. Every study participant was tested every week, in order to i