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

Abstract

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.

Keywords: ABO groups; SARS-CoV-2; anti-A.

Fig. 1

Odds ratio (OR) for CIP and CCPD compared to blood donors (CG), considering O/B vs. A/AB groups. Legend: O/B group was identified as a protective factor only for CCPD (OR = 0·60, 95% CI: 0·45–0·75), whereas for CIP this effect was not identified (OR = 0·85, 95% CI: 0·45–1·25). Multivariate logistic regression; CCPD, COVID‐19 convalescent plasma donors; CIP, COVID‐19 inpatients; *P < 0·001.

Fig. 2

COVID‐19 individuals (n = 295) IgM, IgG, and IgA distribution between A/AB and O/B groups. Legend: O/B group showed an IgM, IgG and IgA median level lower when compared to A/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).Mann–Whitney test.

Fig. 3

Distribution of the frequencies of COVID‐19 individuals (n = 295) neutralizing antibodies between A/AB and O/B groups. Legend: O/B group showed a neutralizing antibody lower value trend and lower frequencies when the titres were higher than 320.

Fig. 4

Linear correlation among COVID‐19 individuals (n = 295) immunoglobulins and neutralizing antibody titres (Log2), into the group A/AB (a) and O/B (b). Legend: Spearman correlation for A/AB group (left) and for O/B group (right). A better correlation between IgG and neutralizing antibodies was found in both O/B and A/AB (r = 0·687 in O/B and r = 0·640 in A/AB). IgM and IgA did not show such good correlations (O/B group IgA r = 0·593; IgM r = 0·430 and A/AB group IgA r = 0·555; IgM r = 0·457).