Hospitalised COVID-19 patients are substantially more likely to harbour autoantibodies. Antibodies directed at their own tissues or at substances their immune cells secrete into the blood -- than people without COVID-19, according to a new study emphasising the need for vaccination.

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Autoantibodies can be early harbingers of full-blown autoimmune disease."If you get sick enough from COVID-19 to end up in the hospital, you may not be out of the woods even after you recover," said PJ Utz, professor of immunology and rheumatology at the Stanford University in the US.

In the study published in the journal Nature Communications, the team looked for autoantibodies in blood samples drawn during March and April of 2020 from nearly 200 COVID-19 patients. Blood samples drawn from other donors prior to the COVID-19 pandemic were used as controls.

The researchers identified and measured levels of antibodies targeting the virus; autoantibodies; and antibodies directed against cytokines, proteins that immune cells secrete to communicate with one another and coordinate their overall strategy. More than 60 per cent of all hospitalised COVID-19 patients, compared to about 15 per cent of healthy controls, carried anti-cytokine antibodies, the scientists found.

This could be the result of immune-system overdrive triggered by a virulent, lingering infection. In the fog of war, the abundance of cytokines may trip off the erroneous production of antibodies targeting them, Utz said. If any of these antibodies block a cytokine's ability to bind to its appropriate receptor, the intended recipient immune cell may not get activated. That, in turn, might buy the virus more time to replicate and lead to a much worse outcome, the team explained.

The finding bolsters the argument for vaccination, he added. Vaccines for COVID-19 contain only a single protein SARS-CoV-2's so-called spike protein or the genetic instructions for producing it. With vaccination, the immune system is never exposed to and potentially confused by the numerous other novel viral proteins generated during infection.

In addition, vaccination is less intensely inflammatory than an actual infection, Utz said, so there's less likelihood that the immune system would be confused into generating antibodies to its own signalling proteins or to the body's own tissues. "Patients who, in response to vaccination, quickly mount appropriate antibody responses to the viral spike protein should be less likely to develop autoantibodies," he said.