Another study shows a single dose of an mRNA vaccine has maximal effects in those with past infection.

Primary, Recall, and Decay Kinetics of SARS-CoV-2 Vaccine Antibody Responses – ACS Nano

Related: France recommends single dose of vaccine if previous Covid infection detected. AND [Preprint] More data showing a single-dose SARS-CoV-2 mRNA vaccine may be enough in individuals with previous COVID-19. AND Another study shows a single dose of mRNA vaccine may be enough for patients with previous Covid-19

Commentary on Twitter

Prior covid? Unless it's a severe case, one-dose mRNA vaccine adds considerable protection and nothing added by 2nd dose. This is now concordant w/ >20 studieshttps://t.co/8Qpuw193zk @acsnano pic.twitter.com/TJNbl8HPy9

— Eric Topol (@EricTopol) June 23, 2021