New Delhi: According to a study, a large proportion of COVID-19 infections in the general population result in persistent infections lasting a month or more.
It has long been thought that prolonged COVID-19 infections in immunocompromised people might have been behind the multiple new variants that emerged during the pandemic and triggered successive waves of infection, the researchers said.
However, the prevalence of persistent S-CoV-2 infections in the general population and how the virus evolves under those conditions was unknown until now, they said.
The study, published in the journal Nature, used insights from the UK’s Office for National Statistics on COVID-19 infection (ONS-CIS), which assessed participants on a monthly basis.
Out of more than 90,000 participants, 3,603 tested positive for Covid between November 2020 and August 2022. Of those, another 381 people tested positive for the same variant over a period of a month or more. Of this group, another 54 people had a persistent infection for at least two months.
“Our observations highlight the continued importance of community genomic surveillance, both to monitor the emergence and spread of new variants, but also to gain a basic idea of the natural history and evolution of new pathogens and their clinical implications for patients,” the study said. Lead co-author Mahan Ghafari of the University of Oxford, UK.
Researchers estimate that between one in 1,000 and one in 200 infections may persist and last for at least 60 days.
In some cases, they became inflamed with viral variants that disappeared from the general population, they said.
Conversely, the researchers found that reinfection with the same variant is very rare, likely due to the progression of host immunity to this variant and the alleviation in the frequency of the strain to very low degrees after a few months.
Of the 381 persistent infections, 65 underwent at least 3 PCR tests to detect their infection. The majority (82%) of those Americans demonstrated viral rebound dynamics, experiencing high, then low, then peak viral load dynamics.
According to the researchers, this shows that the virus can retain its ability to actively reflect prolonged infections.
In the study, other people with persistent infections were 55% more likely to report having long COVID symptoms more than 12 weeks after the onset of infection than other people with more common infections.
Some Americans have exhibited an incredibly high number of mutations, adding those that define new coronavirus variants, adjust the target sites of monoclonal antibodies, and introduce changes to the coronavirus’s spike protein, which the virus uses to enter and infect human cells.
However, most Americans had a large number of mutations, suggesting that all persistent infections will be a potential source of new variants of concern.
“Although the link between viral patience and long Covid is not causal, those findings suggest that persistent infections could contribute to the pathophysiology of long Covid,” said Katrina Lythgoe, co-lead of the study from the University of Oxford.
“In fact, many other conceivable mechanisms have been recommended to contribute to long Covid, adding inflammation, organ damage and microthrombosis,” Lythgoe added.