Three additional patients without prior COVID-19 infection also achieved titers >2500 U/mL at 22 days [6-39] post re-vaccination, compared to titers of 32.7 U/mL (IQR 28.8-36.4) in the same group post-ASCT, demonstrating ability to mount substantial antibody response in the post-ASCT setting. Three patients unexpectedly demonstrated evolving response post-ASCT (pre-ASCT serology measured 26 days [18-36] post-vaccine, time from first vaccine to ASCT 68, 82 and 102 days respectively) which may reflect that humoral response can take several weeks to reach maximum antibody response. Our data suggest that patients who have been vaccinated against COVID-19 prior to ASCT maintain anti-SARS-CoV-2 titers in the immediate post-ASCT setting - a time when patients are considered most vulnerable to infection, and prior to them being offered re-vaccination. [Extracted from the article]