You will have immortal time bias favoring the vaccinated when your definition of "vaccinated" depends on having survived the 3-4 weeks between the first and second doses. So counting people as vaccinated starting at the first dose is correct.
You will have immortal time bias favoring the vaccinated when your definition of "vaccinated" depends on having survived the 3-4 weeks between the first and second doses. So counting people as vaccinated starting at the first dose is correct.
You will have immortal time bias favoring the vaccinated when your definition of "vaccinated" depends on having survived the 3-4 weeks between the first and second doses. So counting people as vaccinated starting at the first dose is correct.