COVID-19 Antigens Found in Plasma 14 Months Post Infection

Using a novel assay, the Simoa detection platform, investigators found the presence of SARS-CoV-2 in patients’ plasma 14 months after their initial infections. The findings were published in The Lancet Infectious Diseases.

It was previously believed the virus cleared in a shorter period of time.

“We believe that our findings are the most definitive to date regarding the persistence of the virus in some shape or form. This is a bit of a surprise to the field, which largely thought that the virus is cleared after the first couple of weeks,” said senior author Jeffrey Martin, MD, MPH, professor, Epidemiology & Biostatistics, UCSF School of Medicine. “The other coronaviruses that we know about in humans…were not believed to be persistent.”

Study Parameters and Findings
The investigators looked at the plasma of 2 cohorts: pandemic era and pre-pandemic era participants. The former group consisted of 171 adults who were evaluated at multiple times in the 14 months following confirmed diagnosis and the investigators referenced that most the participants in this cohort were studied before vaccination or reinfection. This latter cohort (pre-pandemic) included 250 adults and their plasma was collected before 2020.

The diagnostic used to examine the plasma was the Simoa (Quanterix) single molecule array detection platform utilized to measure SARS-CoV-2 spike, S1, and nucleocapsid antigens.

In the pandemic participant cohort, 25% of participants had detectable antigens in at least one time point and the S1 spike was the most prevalent. Additionally, individuals with severe COVID-19 who were hospitalized were found to have greater detection of antigens.

“Compared with those not hospitalized, participants who required hospitalization for acute COVID-19 were nearly twice as likely to have SARS-CoV-2 antigens detected (prevalence ratio 1·97, 95% CI 1·11 to 3·48), an absolute difference of +18·4% (95% CI +0·3 to +36·5),” the investigators wrote. “Among participants not hospitalized, those with worse self-reported health during acute COVID-19 had greater post-acute antigen detection.”

Are There Long COVID Implications?
One of areas around the results of this research might be if there is anything involving Long COVID for individuals with remnants of the virus in the body long-term.

“At a minimum, we have discovered that you can find you can find this virus in your body up to a year later in some patients,” Martin said. “These footprints of the virus may not be causing any harm, but they may and that represents the next frontier of research—just what do the presence of these viral antigens mean in terms of causing people to feel ill with the symptoms of Long COVID?”

Final Takeaways
The investigators suggested that the severity of acute infection with a higher inoculum may have provided the environment for SARS-CoV-2 to remain behind and not clear the body.

“Those individuals who are hospitalized had a more severe course likely had higher amounts of virus in their bodies, greater chance for virus to then take hold in other parts of the body, and essentially set up shop for persistence later on,” Martin said. “We also found that amongst individuals who were not hospitalized, but reported more symptoms (in other words, had a harder time with their COVID-19 infection), had a greater percentage of detectable antigen than individuals who had the mildest cases.”

Reference
Peluso MJ, Swank ZN, Goldberg SA, et al. Plasma-based antigen persistence in the post-acute phase of COVID-19. Lancet Infect Dis. Published online April 8, 2024. doi:10.1016/S1473-3099(24)00211-1