A Dutch man with the longest case of COVID infection ever recorded suffered from the sickness for a record 613 days, with the ailment mutating into a unique new variant that baffled medical researchers, Report informs.

The 72-year-old unnamed patient was diagnosed with the omicron variant in February 2022, according to Time, citing research from the University of Amsterdam.

It is the longest time anyone has been infected with the virus, researchers said.

The patient, who had already been suffering from a blood disease before contracting COVID, immune system failed to produce enough white blood cells or antibodies to combat the virus despite receiving the vaccine multiple times.

While most people can overcome the coronavirus in a few weeks, anything medical professionals tried to help cure the patient from the virus wasn’t working.

Doctors quickly found that his body had become resistant to Sotrovimab — a monoclonal antibody for the early treatment of COVID-19 — after taking over two dozen nose and throat swabs while they searched to find him treatment.

They also discovered that the development of an anti-spike antibody in the first month was minimal and soon realized the patient’s immune system was incapable of ridding the virus.

The patient died in the hospital in the fall of 2023 due to his weakened immune system and underlying blood disorder.