Scientists say a U.K. patient with a severely weakened immune system had COVID-19 for almost a year and a half.
The case underscores the importance of protecting vulnerable people from the coronavirus.
There's no way to know for sure whether it was the longest-lasting COVID-19 infection because not everyone gets tested, but at 505 days, it seems to be a record.
Researchers said the person first tested positive in early 2020, was treated with the antiviral drug remdesiver, but died sometime in 2021.
They would not say what the exact cause of their death was, stating that the person also had other illnesses.
Researchers plan to present several "persistent" COVID-19 cases this weekend at an infectious disease meeting in Portugal.
Their study investigated which mutations arise — and whether variants evolve — in people with super long infections.
These cases are different from long COVID.
Nine patients, who all had weakened immune systems, tested positive for the virus for at least eight weeks, the study showed.
Researchers said two patients had the virus for more than a year.
Five of the patients survived.
Two did not need treatment, two cleared it after treatment and one still has COVID-19, which at the last check the patient was on day 412 with the virus.