Based on current data, the CDC considers individuals to be fully vaccinated when they reach two or more weeks after they've received the second dose in a two-dose regimen (Pfizer or Moderna), or two or more weeks after having received a single-dose vaccine (Johnson and Johnson).
For the particulars of the guidelines, as they now stand, which could change as more data is received and evaluated, and as the impact of the variants are felt, go to:
http://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated-guidance.html
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