When does immunity start after the Pfizer COVID-19 vaccine?

When does immunity start after the Pfizer COVID-19 vaccine?

Data released by the U.S. Food and Drug Administration (FDA) show that COVID-19 protection from the Pfizer/BioNTech vaccine was demonstrated in the clinical trials at about 14 days after the first shot. The FDA said some level of immunity may start sooner, but how much is not certain.