A group from Université de Nantes, etc. has reported on the relationship between anti-Tn and COVID-19 status.
https://www.frontiersin.org/articles/10.3389/fmicb.2021.641460/full
Taking into consideration that Tn-antigen (α-GalNAc) has a structural similarity to blood A-antigen (GalNAcα1-3(Fucα1-2)Galβ1-4GlcNAc), it is easily understood that the level of anti-Tn in bood group A individuals is lower than those in blood groups B and O individuals. The fact that the level of anti-Tn is lower in SARS-CoV-2 infected and developed COVID-19 individuals than controls and asymptomatic individuals would mean that the lower the level of anti-Tn is, the higher the COVID-19 developing possibility is. This does not conflict with the existing report saying that blood group A individuals are prone to develop COVID-19 than blood group O individuals.
https://www.nejm.org/doi/pdf/10.1056/NEJMoa2020283?articleTools=true
In additon, there are almost no changes in anti-T, anti-core-3, anti-Lec, anti-GlcNAcLac, and anti-Gb3.
