Researchers around the world have all come across the same finding over the last two years -- people with schizophrenia are three times more likely to die of COVID-19 than the general population.

That's a higher risk than for people with diabetes, heart disease and several other conditions.

Doctors say this could mean schizophrenia isn't just a mental disease, but a physical one too -- something that has been a theory for some time now.

Doctor Katlyn Nemani is a neuropsychiatrist and research scientist at the Nathan Kline Institute, and was a researcher on a study in the U.S.

She said, “we knew that people with schizophrenia are actually seven times more likely to die from respiratory infections. And you know the association has been found in the opposite direction as well."

"There's evidence that early exposure to some infections like influenza, toxic plasma, herpes infection is associated with developing schizophrenia later in life, not just exposure to those infections, but our immune response to those infections,” Nemani added.

Dr. Nemani said the rare opportunity covid presents is it’s the first time researchers can study the effects on the immune system of a single virus in a single point in time.

If a direct link between schizophrenia and the immune system can be established, it could change how the condition is treated.

“We might be able to develop personalized treatment strategies like immune-modulating therapies that could improve mental and physical health,” said Nemani.

“I think this is sort of moving us in the direction of understanding this better and that might lead to treatments that are potentially curative as opposed to palliative which most of our treatments are at this point,” she continued.

The CDC added schizophrenia to its list of conditions that are high risk for COVID-19 about six months ago.