Long-term serological SARS-CoV-2 IgG kinetics following mRNA COVID-19 vaccine: real-world data from a large cohort of healthcare workers

• Published in: International journal of infectious diseases Vol. 122; pp. 1 - 7
• Main Authors: Oliveira-Silva, Joana, Reis, Teresa, Lopes, Cristiana, Batista-Silva, Ricardo, Ribeiro, Ricardo, Marques, Gilberto, Pacheco, Vania, Rodrigues, Tiago, Afonso, Alexandre, Pinheiro, Vítor, Araújo, Lucília, Rodrigues, Fernando, Antunes, Isabel
• Format: Journal Article
• Language: English
• Published: Canada Elsevier Ltd 01.09.2022; The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases; Elsevier
• Subjects: 6 months; Antibodies, Viral; COVID-19 - diagnosis; COVID-19 - prevention & control; COVID-19 Vaccines; Female; Health Personnel; Humans; Humoral immunity; Immunoglobulin G; mRNA vaccine; Real-world data; RNA, Messenger; SARS-CoV-2; SARS-CoV-2 - genetics; SARS-CoV-2; 6 months; Humoral immunity; Real-world data; mRNA vaccine
• ISSN: 1201-9712; 1878-3511
• DOI: 10.1016/j.ijid.2022.05.026

•There is a decrease in humoral immunity to the BNT162b2 COVID-19 vaccine for six months after vaccination.•Being female, young or seropositive associates with higher titers after vaccination.•Over time, the initial antibody differences tended to converge by gender and age.•The higher titer of seropositive versus naïve after vaccination persisted at six months. This study aimed to assess kinetics and predictive variables of humoral immune response to mRNA SARS-CoV-2 vaccine administration. We collected blood samples before (T0) and 15, 90, and 180 days after vaccination (T1, T2, and T3, respectively). The Quant SARS-CoV-2 Immunoglobulin (IgG) II Chemiluminescent Microparticle Immunoassay was used to determine anti-spike IgG. In almost 3000 healthcare-collected blood samples at the three time points, we found the following: at 15 days postvaccination, 97.6% of subjects presented a robust IgG anti-spike response (>4160 AU/ml); then, at three and six months, it decreased in median 6.5-fold to 35.0% and 3.0-fold to 3.3%, respectively. A linear mixed-effects model supported that female gender, younger age groups, and being seropositive prevaccination maintained higher antibody titers. Curves became tighter with time progression, although titers from seropositive subjects decrease at a slower rate than seronegative ones. These findings strengthen the case for a steep decrease of anti-SARS-CoV-2 antibodies up to six months, suggesting that serological evaluation might guide the need for periodic booster vaccinations in specific groups prone to lower antibody titers.