In our special campaign "Vaccinate India", in partnership with Google, we speak to Dr MA Rabbani, Professor and Head, Department of Cardiology, Jawahar Lal Nehru Medical College Hospital, AMU Aligarh, on how long it takes to develop immunity after taking a Covid vaccine and what the presence of Covid antibodies means for a person's immunity. We also discuss why it's not recommended to get a quantitative antibody test done after taking vaccine shots.