The previous longest known case was 335 days.
A British patient was found to have had the longest known case of Covid-19, testing positive for the virus over 505 consecutive days before their death.
As published in a
study by King’s College London, alongside Guy’s and St Thomas’ NHS Foundation Trust, the now-deceased individual - whose identity remains anonymous - returned continuous positive PCR tests for nearly a year and a half.
The patient was part of research involving nine immunocompromised patients who had all tested positive for Covid for at least eight consecutive weeks.
While the average infection persisted for 73 days, two patients had persistent infections for more than a year.
Conducting the study between March 2020 and December 2021, the patients had weakened immune systems due to organ transplantation, HIV, cancer or medical therapies for other illnesses.
Five of the nine tested did develop at least one mutation seen in variants of concern such as Alpha, Delta and Omicron, while some developed multiple.
That said, researchers noted that none of those involved developed new variants that became widespread variants of concern.
In total, five of the patients tested survived the illness.
Two of those five did not receive any treatment for a SARS-CoV-2 infection and two cleared the infection after treatment with antibody therapies and antivirals.
One individual is said to still have an ongoing infection.
An author of the study, Dr Luke Blagdon Snell, said it provided evidence that "mutations found in variants of concern do arise in immunocompromised patients".
He said this "supports the idea that new variants of the viruses may develop in immunocompromised individuals".
It is worth distinguishing that these particular cases are not the same as long Covid, which refers to when symptoms of the infection persist for an extended period of time after contracting and having gotten rid of the virus.
