Anti‐A and SARS‐CoV‐2: an intriguing association

de Freitas Dutra, Valeria; Bonet‐Bub, Carolina; Yokoyama, Ana Paula H.; Achkar, Ruth; Machado, Rafael Rahal Guaragna; Assunção, Murilo; Candelária, Gabriela; Soares, Camila Pereira; Fachini, Roberta Maria; Fontão‐Wendel, Rita; Hamerschlak, Nelson; Reis, Luiz Fernando Lima; Araujo, Danielle Bastos; Nudelman, Victor; Pinho, Joao R. R.; Rizzo, Luiz V.; Sakashita, Araci M.; Scuracchio, Patrícia; Durigon, Edison Luiz; Wendel, Silvano; Kutner, Jose M.

BACKGROUND: Blood groups and anti‐A isohemagglutinin may be involved in susceptibility to SARS‐CoV‐2 infection. MATERIALS AND METHODS: We retrospectively studied 268 COVID‐19 convalescent plasma donors and 162 COVID‐19 inpatients (total 430 subjects, confirmed by RT‐PCR) and 2,212 healthy volunteer first‐time blood donors as a control group. These were further divided into two groups: those with anti‐A (blood types O and B) and those without it (types A and AB). Titres of nucleoproteins, and neutralizing SARS‐CoV‐2 antibody were measured in the convalescent plasma donors and inpatients. Multivariate logistic regression and non‐parametric tests were applied. RESULTS: Persons having types O or B showed less infection prevalence than those of types A or AB (OR = 0·62, 95% CI 0·50–0·78; P < 0·001), but there was no difference when COVID‐19 inpatients were analysed. Immunoglobulins M, G and A were lower in COVID‐19 subjects of types O or B group than those of A or AB (0·16 vs. 0·19; P = 0·03, 2·11 vs. 2·55; P = 0·02, 0·23 vs. 0·32; P = 0·03, respectively). CONCLUSION: In this retrospective cohort, COVID‐19 individuals were less likely to belong to blood types O and B, and also had lower SARS‐CoV‐2 antibody titres than A and AB individuals. COVID‐19 severity did not associate with the blood groups.