ANTIBODY RESPONSE AFTER SARS-CoV-2 mRNA VACCINE IN NAÏVE AND PREVIOUSLY INFECTED HEALTHCARE WORKERS

Background
Evaluating and monitoring plasma levels of anti-SARS-CoV-2 antibodies in healthcare workers, together with the vaccination of this at-risk population is important for maintaining the viability of the healthcare system, especially during the emergence of new viral variants. The aim of this study is to investigate plasma levels of anti-SARS-CoV-2 antibodies in healthcare providers following full vaccination, in both naïve and previously infected individuals.

Material and methods
Complete data were available for 89 healthcare workers from the larger group of 102 initial participants. Plasma was collected at least one month, and no later than two months after the full dose of an mRNA vaccine, and analyzed by determining the total antibody concentration against the spike protein using an ECLIA kit.

Results
The degree of humoral-specific immune response was at least 5-fold higher in previously infected healthcare workers compared to naïve persons that received the vaccine only. The highest titer was found in office-based staff, relative to those found in doctors and nurses. However, this difference lacks statistical significance. Among previously infected participants, nurses had significantly higher antibody titers, when compared to doctors.

Conclusions
The study revealed a sustained immune response after mRNA vaccine among healthcare workers, with enhanced response in previously infected subjects, highlighting a boosting effect of the vaccine.