Long COVID-19: How much do we really know?

Since the Omicron variant surfaced last Thanksgiving, multiple Omicron subvariants have emerged, including the highly contagious BA.5. It currently is responsible for over 50% of all COVID-19 cases, making it the predominant strain in the United States. Although hospitalizations have been low given the mild characteristic of Omicron, its highly transmissible ability makes it equally formidable. 

As more and more people become infected and the total COVID cases tops 90 million, the looming question of COVID’s long-term effects is beginning to become more clear. About 30 percent of all COVID patients experience persistent debilitating symptoms, such as fatigue, respiratory problems, and brain fog. However, recent publications have shown that COVID could pose more serious effects in many key organs of our body. 

Tiny Blood Clots

One alarming discovery of long COVID was the clots in blood vessels often seen in children. A SPECT-CT scan combines two different types of images: a single-photon emission computed tomography scan, which uses a radiotracer injected into a person’s veins to provide pictures of blood flow, and a standard CT scan for information about lung structure. Doctors can use both to see which parts of the lungs aren’t getting normal blood flow.

When the lungs of 11 youngsters who had severe Long COVID, were scanned, six children weren normal. However, in the other five, the images were striking: Where there should have been bright oranges and yellows, signifying pulsing blood, one lung was nearly completely blue, indicating little flow. Doctors believe tiny blood clots or chronic damage to the lining of blood vessels may be impairing blood flow. The findings were published in The Lancet Child & Adolescent Health.



Immune System

Many doctors believe that the immune system is destabilized by a coronavirus attack and is not able to reset itself. A study was conducted where blood was gathered from 31 Long COVID patients who all had characteristic symptoms months after infection. The team found that white blood cells that typically recruit other cells to sites of infection were highly activated, which may explain why the patients’ levels of interferons, proteins the body makes to fight invaders, were sky high 8 months after infection. The participants also had a dearth of inactivated T cells and B cells, a population of cells that normally putters about awaiting instruction to counter pathogens. This signaled chronic inflammation, which can cause a lot of health problems. 

Yale School of Medicine and Stanford Medicine researched the effect of coronavirus when entered through the nose. The mice that were infected developed inflammation to the brain, a loss of myelin, a sign that chronic inflammation may be driving the cognitive impairment experienced by patients. 

Lingering Virus

Because of the persistence of the symptoms, many believe that it could be due to the virus staying in the body well after initial infection. One doctor, gastroenterologist Herbert Tilg at the Medical University of Innsbruck set out to look for molecular traces of virus in the gut, a favorite hunting ground for researchers studying SARS-CoV-2. The gut is far easier for doctors to access than many other organs, such as the lungs or the brain, and is thought to harbor virus longer than blood, which tends to clear a pathogen more quickly.

Out of 46 patients, 21 of whom had Long COVID, the doctor found that all patients with Long COVID harbored viral DNA in their gut, in comparison to those with acute COVID-19, of which more than half had no signs of virus. Although it doesn’t prove that the virus is harming people, the persistence of the virus can be harmful, as many patients are becoming desperate, resorting to antivirals that could be dangerous.

Review Questions

1. Why were patient levels of interferons higher after infection?
2. What was the difference in viral DNA between those who had Long COVID and those who did not in their gut?

Citations

https://www.yalemedicine.org/news/5-things-to-know-omicron

https://www.cdc.gov/coronavirus/2019-ncov/hcp/clinical-care/post-covid-science.html

https://www.science.org/content/article/what-causes-long-covid-three-leading-theories