BACKGROUND Immunization against SARS-CoV-2, the causative agent of COVID-19, occurs via natural infection or vaccination. However, it is currently unknown how long infection- or vaccination-induced immunological memory will last.METHODS We performed a longitudinal evaluation of immunological memory to SARS-CoV-2 up to 1 year after infection and following mRNA vaccination in naive individuals and individuals recovered from COVID-19 infection.RESULTS We found that memory cells are still detectable 8 months after vaccination, while antibody levels decline significantly, especially in naive individuals. We also found that a booster injection is efficacious in reactivating immunological memory to spike protein in naive individuals, whereas it was ineffective in previously SARS-CoV-2–infected individuals. Finally, we observed a similar kinetics of decay of humoral and cellular immunity to SARS-CoV-2 up to 1 year following natural infection in a cohort of unvaccinated individuals.CONCLUSION Short-term persistence of humoral immunity, together with the reduced neutralization capacity versus the currently prevailing SARS-CoV-2 variants, may account for reinfections and breakthrough infections. Long-lived memory B and CD4+ T cells may protect from severe disease development. In naive individuals, a booster dose restored optimal anti-spike immunity, whereas the needs for vaccinated individuals who have recovered from COVID-19 have yet to be defined.FUNDING This study was supported by funds to the Department of Experimental and Clinical Medicine, University of Florence (Project Excellence Departments 2018–2022), the University of Florence (project RICTD2122), the Italian Ministry of Health (COVID-2020-12371849), and the region of Tuscany (TagSARS CoV 2).
Alessio Mazzoni, Anna Vanni, Michele Spinicci, Giulia Lamacchia, Seble Tekle Kiros, Arianna Rocca, Manuela Capone, Nicoletta Di Lauria, Lorenzo Salvati, Alberto Carnasciali, Elisabetta Mantengoli, Parham Farahvachi, Lorenzo Zammarchi, Filippo Lagi, Maria Grazia Colao, Francesco Liotta, Lorenzo Cosmi, Laura Maggi, Alessandro Bartoloni, Gian Maria Rossolini, Francesco Annunziato
This file is in Adobe Acrobat (PDF) format. If you have not installed and configured the Adobe Acrobat Reader on your system.
PDFs are designed to be printed out and read, but if you prefer to read them online, you may find it easier if you increase the view size to 125%.
Many versions of the free Acrobat Reader do not allow Save. You must instead save the PDF from the JCI Online page you downloaded it from. PC users: Right-click on the Download link and choose the option that says something like "Save Link As...". Mac users should hold the mouse button down on the link to get these same options.