> For the purpose of this surveillance, a vaccine breakthrough infection is defined as the detection of SARS-CoV-2 RNA or antigen in a respiratory specimen collected from a person ≥14 days after they have completed all recommended doses of a U.S. Food and Drug Administration (FDA)-authorized COVID-19 vaccine.

Redline changes were made in April 2021, https://www.cms.gov/files/document/qso-20-38-nh.pdf

> Fully vaccinated” refers to a person who is ≥2 weeks following receipt of the second dose in a 2-dose series, or ≥2 weeks following receipt of one dose of a single-dose vaccine. “Unvaccinated” refers to a person who does not fit the definition of “fully vaccinated,” including people whose vaccination status is not known, for the purposes of this guidance