Doctors have identified an 'antibody signature' that could help predict which patients are most at risk of developing long Covid, the debilitating condition where symptoms persist for months after infection. Researchers at University Hospital Zurich analysed blood samples from 175 Covid-19 patients and 40 healthy volunteers, finding that low levels of specific antibodies, IgM and IgG3, were more common in those who later developed long Covid, also known as post-acute Covid-19 syndrome (Pacs).
When combined with the patient's age, whether they had asthma, and details of their initial symptoms, the antibody signature allowed doctors to classify patients into moderate, high, or very high risk of long-term illness. The findings, published in Nature Communications, were validated in a separate group of 395 Covid patients followed for six months.
'Overall, we think that our findings and identification of an immunoglobulin signature will help early identification of patients that are at increased risk of developing long Covid, which in turn will facilitate research, understanding and ultimately targeted treatments for long Covid,' said Professor Onur Boyman, who led the research. The team followed 134 patients for up to a year after infection.
The test cannot predict risk before infection, as it requires details of symptoms. However, Dr Carlo Cervia, first author, noted that people with asthma and low baseline levels of IgM and IgG3 could assume they are at increased risk. He added that this should motivate high-risk groups to get vaccinated and prevent long Covid.
Experts welcomed the study but called for larger replication. Dr Claire Steves, clinical senior lecturer at King's College London, said: 'We urgently need to scale up research on how to prevent this happening.' Dr David Strain, from the University of Exeter, noted similarities to ME and said comparisons between the diseases could benefit both fields of study.
