Assessment of the Humoral Immune Response Following COVID-19 Vaccination in Healthcare Workers: A One Year Longitudinal Study

• Published in: Biomedicines 2022-06, Vol.10 (7), p.1526
• Main Authors: Chivu-Economescu, Mihaela, Vremera, Teodora, Ruta, Simona Maria, Grancea, Camelia, Leustean, Mihaela, Chiriac, Daniela, David, Adina, Matei, Lilia, Diaconu, Carmen C., Gatea, Adina, Ilie, Ciprian, Radu, Iuliana, Cornienco, Ana Maria, Iancu, Luminita Smaranda, Cirstoiu, Catalin, Pop, Corina Silvia, Petru, Radu, Strambu, Victor, Malciolu, Stefan, Popescu, Corneliu Petru, Florescu, Simin Aysel, Rafila, Alexandru, Furtunescu, Florentina Ligia, Pistol, Adriana
• Format: Article
• Language: English
• Subjects: Age; Antibodies; Autoimmune diseases; Body mass index; booster dose; Coronaviruses; COVID-19 vaccines; Disease prevention; Disease transmission; Enzymes; Health care; healthcare workers; Hospitals; host factors; immune response; Immune response (humoral); Immunoglobulin A; Immunoglobulin G; Infections; Longitudinal studies; Medical personnel; mRNA; mRNA vaccines; Nucleocapsids; Proteins; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Software; vaccination; Vaccines; Variance analysis
• ISSN: 2227-9059; 2227-9059
• DOI: 10.3390/biomedicines10071526

The continuous variability of SARS-CoV-2 and the rapid waning of specific antibodies threatens the efficacy of COVID-19 vaccines. We aimed to evaluate antibody kinetics one year after SARS-CoV-2 vaccination with an mRNA vaccine in healthcare workers (HCW), with or without a booster. A marked decline in anti-Spike(S)/Receptor Binding Domain (RBD) antibody levels was registered during the first eight months post-vaccination, followed by a transitory increase after the booster. At three months post-booster an increased antibody level was maintained only in HCW vaccinated after a prior infection, who also developed a higher and long-lasting level of anti-S IgA antibodies. Still, IgG anti-nucleocapsid (NCP) fades five months post-SARS-CoV-2 infection. Despite the decline in antibodies one-year post-vaccination, 68.2% of HCW preserved the neutralization capacity against the ancestral variant, with a decrease of only 17.08% in the neutralizing capacity against the Omicron variant. Nevertheless, breakthrough infections were present in 6.65% of all participants, without any correlation with the previous level of anti-S/RBD IgG. Protection against the ancestral and Omicron variants is maintained at least three months after a booster in HCW, possibly reflecting a continuous antigenic stimulation in the professional setting.