Evaluation of hematological abnormalities in subjects vaccinated with BNT162b2 in a longitudinal cohort of the CORE study

Abstract

Background: Vaccination is considered the most effective preventive strategy to fight COVID-19. The aim of this study was to evaluate two critical concerns about: 1) the kinetic response of IgG and IgM, and: 2) the hematological abnormalities in a longitudinal cohort of health-care workers (HCW) who had received 2 doses of BNT162b2 mRNA-based vaccine. Method(s): Blood and nasopharyngeal swabs were collected from 46 volunteers' participants, previous written consensus, with presumable no symptoms of COVID-19. Anti-SARS-CoV-2 serum immunoglobulin G (IgG) and M (IgM) and hematological parameters were examined. Multivariable mixed-effects models for repeated measure analysis were adopted to evaluate time changes in IgG, IgM and hematological parameters, and to investigate associations with vaccination response. Result(s): Forty-six subjects (N.=46;31.8% men;68.2% women;mean age near 36 years-old) were enrolled among healthcare workers of IRCCS MultiMedica (Milan, Italy). Overall, increase in serological IgG concentration appeared mainly between 21-28 days after the 1st dose, whereas IgM did not reach positivity in all cases. Mean blood cells counts were in normal range but we observed a significant reduction of total white blood cells and absolute lymphocyte counts after the 1st dose, persisting until the day 28. The increase of monocytes and neutrophils the day after the 1st dose subsequently decayed significantly. Eosinophils concentration showed a tendency to increase over time. Peripheral blood smear showed a growing frequency of atypical lymphocytes (lympho-variants), and of plasmacytoid forms, whereas no difference was found in large granular lymphocytes (LGL), although a decay after the boost was evident. The stratification of subjects, relative to the timing of IgG increase, showed the occurrence of 3 different patterns after vaccination, namely early-responders (R+), late-responders (R-) and pauci-responders (PR) with a peculiar kinetics of hematological parameters. Lymphocytes were significantly associated with total IgG: lower in R+ and PR compared to R- (P=0.0193 and P=00054, respectively). Conclusion(s): In healthy subjects, anti SARS-CoV-2 vaccination induced a variety of non-pathologic abnormalities. The response to vaccination was not equal in the groups examined. In PR group a major difference occurred with respect to R- and R+. This work adds novel insight into the puzzle of changes induced by SARS-CoV-2 virus.Copyright © 2022 EDIZIONI MINERVA MEDICA.