The spectrum of possible reactions to COVID-19 is staggeringly wide. On one end lies asymptomatic patients and on the other you have life-threatening complications, such as blood clot formations. Research into the ways COVID-19 can damage the body is ongoing.
A case report published in the Annals of Internal Medicine detailed how three COVID-19 patients in Italy developed symptoms linked to a rare, muscle-weakening autoimmune disorder called myasthenia gravis.
The team, from Garibaldi Hospital in Catania, Italy, said this is the first time a condition between the virus and the disorder has ever been reported.
Myasthenia gravis is a rare long-term condition that causes muscle weakness.
As the NHS explains, it's an autoimmune condition, which means it's the result of the immune system (the body's natural defence against infection) mistakenly attacking a healthy part of the body.
The first patient was a 64-year-old man who had a fever that reached as high as 102.2F (39C) for four days days.
Five days after his fever began, he developed double vision and muscle fatigue. He soon tested positive for COVID-19.
Doctors later diagnosed the patients with myasthenia gravis after analysing his facial nerves and his reaction to receiving a medication.
The second patient was a 68-year-old man who had fever as high as 101.8F (38.8C) for seven days.
On the seventh day, he developed the same symptoms as the first patient in addition to swallowing difficulty, leading to a diagnosis of the autoimmune disorder.
The third patient was a 71-year-old woman who had a cough and fever up to 101.4F (38.6C) for six days.
Five days after her symptoms began, she developed droopy eyelids, double vision and soft speech. One day later, she developed difficulty swallowing.
She tested positive for COVID-19 and was subsequently diagnosed with myasthenia gravis.
The time from the coronavirus infection to the beginning of myasthenia gravis symptoms "is consistent with the time from infection to symptoms in other neurologic disorders triggered by infections," the researchers said.
They added that the findings add to "the growing evidence of other neurologic disorders with presumed autoimmune mechanisms after COVID-19 onset".How is myasthenia gravis treated?
While there is no cure, treatment can help keep the symptoms of myasthenia gravis under control so that you're able to live a largely normal life, says the NHS.
"But some people need ongoing treatment, and occasionally emergency treatment in hospital may be necessary if the condition suddenly gets worse," says the health body.