Jean-Laurent Casanova, M.D., Ph.D.; Image credit: The Rockefeller University

Investigators have pinpointed a mechanism that accounts for why some people — and notably older adults — suffer more severe COVID-19 illness than others.

A study that included nursing home residents has found that auto-antibodies, which mistakenly target a person’s own tissues or organs, block a key part of the antiviral immune response called type 1 interferon response. 

These auto-antibodies, which can neutralize the body’s important antiviral response, sharply increase after age 60, according to Jean-Laurent Casanova, M.D., Ph.D., of the University of Paris and The Rockefeller University, in New York City. What’s more, these auto-antibodies are present in approximately 4% of uninfected individuals aged 70 years and older and account for 20% of COVID-19 deaths, he and his colleagues reported.

This findings may explain some of the variability seen in COVID-19 illness in older people. They also have implications for treatment timing and vaccination, the authors said.

Clinical implications

The study results have important clinical implications, according to the researchers. It is “quick and easy” to test for auto-antibodies against type 1 interferons in people infected with SARS-CoV-2, they wrote. And identifying those auto-antibodies may help clinicians determine which patients may benefit from early treatment, early hospital admission and certain antiviral therapies that could boost their weakened immune responses, they said.

In addition, people with auto-antibodies against type 1 interferons should be prioritized for COVID-19 vaccination, and live attenuated vaccines should not be given to these individuals, they cautioned.

Nursing homes residents accounted for

Investigators were able to include nursing home residents in the study with the participation of Trinity College Dublin and Tallaght University Hospital in Ireland. Data came from the NH-COVAIR project, a longitudinal investigation of COVID-19 in Irish nursing home residents. This ongoing project is examining the relationship between frailty, clinical outcomes, immunophenotype and vaccine response in nursing home residents.

The study results and ongoing research offers critical information about the underlying immunological reasons for severe COVID-19 illness in older adults, said co-author Adam Dyer, M.D., a geriatrician at both institutions.

“As clinicians, we see an immense variability in morbidity and mortality in older adults infected with this virus, and exploring the underlying immunological reasons why is an urgent unmet clinical need,” he concluded.
Additional clinical implications for these results can be found in the study, published in the journal Science Immunology.