Aspects of Humoral Immunity after Vaccination with Bnt162b2: A Small Study

Starting from December 2020, vaccination against COVID-19 became available in Romania. There are a lot of uncertainties regarding the kinetics of immunity and its persistance over time. This is a small prospective study developed between January-September 2021 in the Infectious Diseases Clinic from Craiova and comprising 61 subjects immunised with BNT162b2 (Comirnaty). We have found that after two doses of vaccine there is a strong humoral response, but the immunity lowers six months later. Subjects with a diagnosis of COVID-19, previously or in between the two doses, have had the most significant immunological response, but, also, the sharpest decline in antibody titer. The immune response seems to be the same, regardless the gender of the subjects. There are a variety of responses at the individual level, but overall vaccine effectiveness is 96.72% two weeks following immunisation and 88.52% after six months; however for those who have been in contact with the virus, they all had an antibody titer well above the laboratory limit.