Humoral response against spike protein enhanced by fifth and sixth COVID-19 mRNA vaccine in the uninfected and infected subjects

• Published in: Human vaccines & immunotherapeutics Vol. 19; no. 3; p. 2278376
• Main Authors: Kato, Hideaki, Kurosawa, Takayuki, Horikawa, Kazuo, Kimura, Yayoi, Miyakawa, Kei, Ryo, Akihide, Goto, Atsushi
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 15.12.2023; Taylor & Francis Group
• Subjects: Antibodies, Viral; Antibody; Brief Report; chemiluminescent enzyme immunoassay; COVID-19; COVID-19 - prevention & control; COVID-19 Vaccines; Humans; Immunoglobulin G; mRNA Vaccines; nucleocapsid protein; SARS-CoV-2; Spike Glycoprotein, Coronavirus; spike protein; Vaccination; COVID-19; SARS-CoV-2; humoral immunity; COVID-naïve; Antibody; spike protein; nucleocapsid protein; Lumipulse; additional vaccination; chemiluminescent enzyme immunoassay
• ISSN: 2164-5515; 2164-554X; 2164-554X
• DOI: 10.1080/21645515.2023.2278376

Antibody obtained by the coronavirus disease-19 (COVID-19) mRNA vaccine declines over time, and additional vaccinations are offered. It is not clear how repeated vaccination affects humoral immunity in uninfected individuals. We analyzed immunoglobulin G for spike protein (S-IgG) titers in COVID-19 uninfected and infected individuals vaccinated up to six times. The geometric mean S-IgG titers were 575.9 AU/mL and 369.0 AU/mL in those who received 6 and 5 doses less than 180 days after the last vaccination in uninfected subjects. In the 180-360 days after the last vaccination, the geometric mean S-IgG titers were 237.9 AU/mL and 128.6 AU/mL in the uninfected subjects who underwent five-dose and four-dose groups, respectively. Multivariate analysis showed that S-IgG titer increased 1.261-fold with each additional dose of mRNA vaccine. The S-IgG titers were 2.039-fold higher in the COVID-infected subjects compared to uninfected subjects. The positivity rate of nucleocapsid antibodies, suggesting a history of COVID-19, decreased 82% and 30% of COVID-infected cases after 180 and 360 days of infection, respectively. This result suggested that repeated vaccination with the COVID-19 mRNA vaccine may increase antibody titer in uninfected subjects.