UK doctors believe they have documented the longest-running coronavirus infection ever recorded among Covid cases — a patient they treated had detectable levels of the virus for more than 16 months, or 505 days, in total.
The individual, who was not identified, had other underlying medical conditions and died in hospital in 2021.
Persistent infections like this are still rare, doctors say.
Most people clear the virus naturally, but the patient in question had a severely weakened immune system.
Chronic infections like these need to be studied to improve our understanding of the disease caused by the coronavirus and the risks it can pose, experts say.
The patient first caught covid in early 2020. Then he showed symptoms, and the infection was confirmed with a PCR test.
The man was in and out of the hospital many times over the next 72 weeks, both for routine checkups and medical care.
On each occasion — about 50 in total — he tested positive for the virus, which means he still had covid.
The doctors, linked to King’s College London and the NHS (the UK’s public health service), say that detailed laboratory analyzes have surprisingly revealed it to be the same infection, rather than new infections.
And the patient could not get rid of it even after receiving antiviral drugs.
This is different from the so-called “long covid”, when symptoms persist after the infection has disappeared.
Luke Blagdon Snell is one of the doctors who will present the results of this case at a medical conference — the European Congress of Clinical Microbiology and Infectious Diseases.
“Tests of swab of this patient’s throat that were always positive. He never had a negative test. And we can say it was an ongoing infection because her genetic signature — the information that we got from sequencing the viral genome — was unique and constant in that patient,” Snell said.
Prolonged infections are rare but worrisome, the researchers say, because they can give rise to new variants of covid — although this was not the case in this case or others they studied.
Snell added: “The virus is still adapting to the human host when people have been infected for a long time. This could provide an opportunity for Covid to accumulate new mutations.”
“Some of these patients that we studied have mutations that were seen in some of the variants of concern.”
He emphasized that none of the nine patients examined had generated a dangerous new variant.
Someone with a chronic infection may not be contagious to others, he added.
David Strain from the University of Exeter School of Medicine in England explained: “We know that every time the virus replicates it must reproduce its RNA — equivalent to manually copying a textbook.”
“So if we transcribe an entire book by hand, we’re probably going to make mistakes, and the same goes for the virus. Each copy will produce mutations.”
“Although the (variant) omicron did not arise in these particular individuals, it demonstrates a very clear pathway by which vaccine-resistant variants can arise. Whereas with (variant) BA.2 we were lucky, that the mutation is associated with a less severe disease, there is no guarantee that the same will happen with the next iteration,” he concluded.