UK researchers identify COVID case that lasted 16 months — longest infection period

Researchers in the United Kingdom (UK) say the longest period of COVID infection in a person lasted 505 days.

The previous longest known COVID infection period in a human was recorded as 335 days.

According to a statement by the European congress of clinical microbiology and infectious diseases, the researchers carried out a study that involved nine immunocompromised patients who tested positive for the virus for at least eight weeks.

The research team, from King’s College London, and Guy’s and St Thomas’ NHS Foundation Trust, were interested in how COVID changes over time in immunocompromised individuals.

They said infections in the patients persisted for 73 days on average, but two had persistent infections for more than a year.

The patients, studied between March 2020 and December 2021, were said to have had weakened immune systems due to organ transplantation, HIV, or cancer.

Overall, five of the nine patients were said to have survived, with one still infected. At their last follow-up in early 2022, that patient had been infected for 412 days.

The scientists said if the patient still tests positive at their next appointment, they would likely pass the longest known infection of 505 days as described in the new study.

They added that the results from the study provide evidence that mutations found in variants of concern arise in immunocompromised patients and so supports the idea that new variants of the viruses may develop in immunocompromised individuals.

“It is important to note, however, that none of the individuals in our work developed new variants that became widespread variants of concern,” they said.

“Additionally, whilst this work shows variants could arise in immunocompromised individuals, whether the previous variants of concern like Alpha, Delta and Omicron arose in this manner remains unknown.”