COVID-19 is defined as a respiratory infectious disease. But the effects of the novel Coronavirus are certainly not limited to one organ.
Dozens of autopsies conducted recently show evidence that SARS-CoV-2 is found throughout the body, including in the lungs, heart, spleen, kidneys, liver, colon, chest, muscles, nerves, reproductive tract, eyes, and brain.
In one particular autopsy, remnants of the novel coronavirus were found in the brains of patients who died 230 days after they started showing symptoms.
"Our data show that in some patients SARS-CoV-2 can cause systemic infection and persist in the body for months," the study authors concluded.
The study, led by researchers at the United States National Institutes of Health (NIH), writes that, previously, autopsies on patients who contracted COVID-19 had shown early signs of multi-organ spread. The genetic remnants of the virus appear in various tissues, organs and fluids.
In July 2020, a further autopsy showed evidence of blood clots in almost every vital organ of those who had contracted COVID-19.
New research from the NIH now replicates and confirms these results in more detail than ever before. The researchers estimate their latest findings are the most comprehensive analysis so far of the 'persistence' of SARS-CoV-2 in the human body.
The study involved 44 autopsies. The researchers carefully detected and quantified the messenger RNA levels of SARS-CoV-2 in 85 locations and fluids. This genetic information indicates where the virus may have replicated during a person's lifetime.
From autopsies conducted in April 2020 to March 2021, researchers found older, unvaccinated individuals who died of COVID-19 displayed multiple signs of SARS-CoV-2 replication in a total of 79 sites and body fluids.
What's more, few changes were noticed within two weeks of the first symptoms appearing. The lungs showed the most inflammation and injury, whereas the brain and other organs showed no significant tissue changes despite the large viral load. The author is not sure why this is so. It could be, for example, that the human immune system in the lungs isn't as good as other organs.
"Our results show that although the highest burden of SARS-CoV-2 is in the respiratory tissue, the virus can spread throughout the body," the researchers concluded.
How the virus spread so far and wide is another mystery that needs to be solved. Autopsies in this study did not always show detectable remnants of virus in blood plasma, which suggests that the pathogen may have spread by other means.
Understanding how SARS-CoV-2 spreads and persists in the human body can reveal a lot about why some patients suffer long-term COVID-19 (long COVID).
The NIH study did not specifically experiment with older COVID patients, but the results are relevant to possible treatment plans.
Antiviruses such as Paxlovid, for example, can help the human immune system clear virus cells from tissues, organs and fluids that may be difficult to reach. Perhaps, in turn, it can help reduce lingering symptoms.
"We hope to replicate data on the persistence of the virus and study its relationship to long COVID," said co-author Stephen Hewitt, of the National Cancer Institute.
"In less than a year we have about 85 cases, and we are working to expand this effort," he concluded.