Nikhil Prasad Fact checked by:Thailand Medical News Team Sep 29, 2026 35 minutes ago
COVID-19 may do more than trigger antibodies against the coronavirus itself. New research suggests SARS-CoV-2 infection can also disturb naturally occurring antibodies linked to a person’s ABO blood group, producing surprisingly unpredictable changes that could have implications for immunity, blood transfusion, organ transplantation, and potentially autoimmunity.
.jpg)
COVID-19 may unexpectedly alter naturally occurring blood group antibodies, potentially opening new questions
about immunity, transfusion, transplantation, and post-viral immune effects.
The findings provide a new perspective on the long-observed relationship between blood type and COVID-19, while raising questions about whether infection can temporarily reshape parts of the immune system once considered relatively stable.
Tracking Blood Group Antibodies Through COVID-19
Researchers followed 65 hospitalized COVID-19 patients, collecting serum at three stages: hospital admission, roughly two to three weeks after symptom onset, and shortly before discharge or death.
In total, the team analyzed 195 serum samples using a high-throughput Luminex bead array containing 25 different glycans. They measured three major antibody classes—IgG, IgM, and IgA—directed against ABO(H) blood group structures.
Instead of remaining relatively constant, anti-ABO(H) antibodies showed striking differences between patients and frequently changed during infection.
Among 65 patients, 11 had anti-ABO(H) IgG signals below the study’s detection threshold. Of the remaining 54, most displayed dynamic changes during the course of their illness.
Some patients experienced sharp declines in antibody levels, while others developed temporary antibodies against particular blood group structures. In some cases, antibodies disappeared and subsequently returned.
The researchers described these IgG, IgM, and IgA fluctuations as unpredictable, suggesting SARS-CoV-2 can be associated with a highly individualized alteration of naturally occurring antibody responses.
Blood Group O Produced a Striking Antibody Pattern
One of the clearest differences involved people with blood group O.
The study included 27 group O, 20 group A, 16 group B, and two group AB patients. Group O patients had significantly higher IgG and IgA antibodies against all seven tested A glycans than group B patients. They also had significantly higher IgG and IgA responses against all seven tested B glycans than group A patients. Interestingly, the same clear difference was not found for IgM antibodies.
The researchers also found an association between blood type and clinical outcomes. ICU transfer occurred in 90% of group A patients compared with 63% of group O patients, while mortality was 42.1% versus 26.3%, respectively.
However, the researchers emphasized the limited sample size, meaning these figures should not be interpreted as proof that blood group O itself protected patients.
Could IgA Offer an Immune Advantage?
A particularly intriguing finding involved anti-ABO(H) IgA, an ant
ibody class with an important role in immune protection.
Mortality was 19.04% among 21 patients with high anti-ABO(H) IgA, compared with 36.36% among 44 patients with lower levels.
Because group O patients were more likely to possess anti-ABO(H) IgA, the researchers proposed that these antibodies might potentially contribute to stronger or more localized early immune defenses.
That remains a hypothesis. The study did not demonstrate that IgA directly protected patients or caused the mortality difference. Researchers say future work should determine whether anti-ABO(H) IgA can directly neutralize SARS-CoV-2 at its point of entry and whether serum and secretory IgA behave differently.
Why These Antibody Shifts Could Matter After Infection
The repercussions could extend beyond COVID-19 itself. ABO antibodies are extremely important in blood transfusion and organ transplantation, particularly when doctors are considering ABO-incompatible procedures. Antibody levels and their specificity can affect compatibility and transplantation outcomes.
The study notes that anti-ABO(H) levels have generally been regarded as relatively stable. The discovery that they can fluctuate during COVID-19 therefore introduces another potential consideration for people who subsequently become blood donors or require solid-organ transplantation.
This does not mean people who have had COVID-19 are unsafe donors or transplant candidates. Rather, the findings suggest recent infection could be an underrecognized factor influencing antibody titers and that further research is needed to determine whether these changes are clinically significant.
Researchers Also Detected Antibodies Against Self
Another finding may have implications for understanding post-viral autoimmunity.
Researchers detected antibodies against self-glycan structures in a small proportion of patients, including antibodies recognizing A1 and A2 glycan antigens and the i antigen in two blood group A patients.
Such autoantibodies are important because antibodies directed against the body’s own structures can participate in autoimmune disease. The researchers said their observations raise the possibility of SARS-CoV-2-related immune cross-reactivity against self-antigens.
However, the study cannot establish that COVID-19 caused autoimmune disease in these patients, and the finding involved only a very small number of people. That distinction is important for interpreting this
Thailand Medical News report.
Institutions
The researchers involved in the study were affiliated with Beth Israel Deaconess Medical Center, Harvard Medical School, the National Center for Functional Glycomics, Brigham and Women’s Hospital, the Joint Program in Transfusion Medicine, Emory University School of Medicine, and The First Affiliated Hospital of Zhejiang University School of Medicine.
Conclusions
The findings suggest SARS-CoV-2 infection may have a broader effect on the antibody landscape than previously recognized, with anti-ABO(H) antibodies changing substantially and unpredictably in some patients. Those shifts could eventually prove relevant to immune defense, transfusion medicine, and transplantation, while the detection of self-reactive antibodies raises additional questions about post-viral immune effects.
However, the study was relatively small, subgroup numbers were limited, and antibody testing was performed at a single serum dilution rather than through complete titration. Healthy controls are also needed to distinguish infection-related changes from pre-existing antibody patterns.
Larger studies must now determine whether these antibody fluctuations produce meaningful clinical consequences or are primarily markers of the immune response to infection.
The study findings were published in the peer reviewed journal: ACS Chemical Biology.
https://pubs.acs.org/acbcct/article/doi/10.1021/acschembio.6c00447/5439447/Dynamics-of-Anti-ABO-H-Antibody-Expression-in-SARS
Read Also:
https://www.thailandmedical.news/articles/coronavirus
https://www.thailandmedical.news/articles/long-covid
Share
Tweet
Share
