Since the beginning of the pandemic, it has been clear that Covid-19 usually has more severe effects on older people than their younger counterparts. But even within individual age groups, the effect Covid-19 has on a person is far from predictable. Some can be asymptomatically infected with the virus and be none the wiser, others have flu-like symptoms that last a few days, but in the worst cases, it can lead to hospitalisation and death. This we know from the past months, but what we do not know is why some react so badly to the virus and why the severity of symptoms is so varied for those in the same age group.
This is a question which researchers from Trinity’s School of Medicine, alongside Tallaght University Hospital and research facilities spread across 38 countries, have been endeavouring to answer. The collaborative study examines why morbidity and mortality are so varied for Covid-19 infections across patients; why more than 4.5 million deaths have been caused by a disease that for others is nothing more significant than a cold.
Well, some of this variability is caused by a blocking of an important viral immune response in some patients. Antibodies are one of our bodies’ most important mechanisms at fighting viruses. However, some antibodies, called autoantibodies, target our own tissue and organs rather than the virus. The autoantibodies are capable of blocking the important “type 1 interferon immune response” and prevent the body from protecting itself via this vital mechanism.
It appears that the presence of these autoantibodies is considerably higher in older adults over 60 years old, with over 4% of over 70s exhibiting them. The researchers estimate that the action of these autoantibodies is responsible for up to 20% of Covid-19 related deaths, so approximately 900,000 deaths since the beginning of the pandemic. The researchers believe that some of the variability in the severity of the Covid-19 response in older adults is partially due to the presence or lack of autoantibodies.
Dr Adam Dyer, ICAT Fellow & Specialist Registrar in Geriatric Medicine, Trinity College Dublin & Tallaght University Hospital and co-author of the study said:
“The findings of this landmark study emphasise the need to explore immune-system variability in older adults. 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.”
The research by Trinity and Tallaght hospital was conducted alongside other work encompassed in a longitudinal Covid-19 study on nursing home patients, NH-COVAIR.
Co-author of the study, Consultant Physician in Geriatric and Stroke Medicine in the Department of Age-related healthcare based at Tallaght University Hospital and Clinical Associate Professor in Medical Gerontology in Trinity College Professor Seán Kennelly said:
“This important study explains why COVID-19 can have severe clinical consequences in some people but not others. We were delighted to ensure Tallaght University Hospital and Trinity College Dublin were represented amongst this international consortium of leading clinical research institutes. We are extremely grateful for the generous support of local nursing home residents, staff, and families who participated in this study.”
Given the new information on the inhibition of the type 1 interferon immune response by the autoantibodies, doctors could be better able to predict those who will have the most severe infections and worst outcomes of a Covid-19 infection and hospitalise them earlier, or potentially who would benefit from interferon beta therapy to compensate for the damage done by their autoantibodies.