Ongoing COVID-19 vaccinations are essential for preparing against variants and potential future strains of COVID-19. In this context, determining who should be prioritized for these vaccinations is critically important for controlling the spread of infection and preventing severe illness.
A research team led by Professor Shingo Iwami of the Graduate School of Science, Nagoya University and Professor Masaharu Tsubokura of Fukushima Medical University analyzed changes in IgG(S) antibody titers induced after the two primary doses and one booster dose of COVID-19 vaccines. The study covered 2,526 residents of Fukushima Prefecture from April 2021 to November 2022, using a unique analytical method that combines mathematical modeling and AI. IgG(S) antibodies are produced through vaccination or infection, and higher levels indicate stronger immunity against the virus. The analysis identified three distinct population groups among vaccinated individuals: a "durable type" that exhibits high antibody titers maintained over a long period; a "vulnerable type" with insufficient antibody induction and rapid decay; and a "rapid-decliner type" that initially shows high antibody titers, but these subsequently decrease rapidly. The study found that both the vulnerable and rapid-decliner groups had experienced breakthrough infections early on. Furthermore, individuals who had breakthrough infections showed significantly lower serum IgA(S) antibody titers within 100 days after their booster dose compared with those who had not.
This research is useful for making effective use of limited medical resources and establishing an efficient vaccination system. It is expected to contribute to planning immunity enhancement policies at both individual and population levels for future pandemics.
(Article: Masanori Nakajo)
