Researchers Are Getting a Grip on “Long COVID”

One of the most persistent medical mysteries surrounding COVID-19 is what’s driving the long-term neurological effects experienced by so-called “long COVID” patients, who can suffer from symptoms like poor concentration, confusion, and mental fatigue (often collectively referred to as “brain fog”) for weeks, months, or even years after infection.

Some background:

Research describing the symptoms of long COVID has been going on since summer 2020, after people suffering the symptoms coined the term that spring as a way to describe their inability to shake the effects of COVID.

To date, researchers haven’t found a definitive answer as to what’s causing some people to experience long COVID symptoms, though scientists do know the virus can enter the brain and cause a build up of inflammatory substances.

A new study by researchers at Keio University in Tokyo may have finally solved the mystery, finding the virus can infect “microglia,” the brain’s primary immune cells.

Study highlights:

The researchers used stem cells to create artificial neurons (i.e., nerve cells) and microglia, infecting the cells with “pseudoviruses” resembling SARS-CoV-2 and its subsequent strains.

Without getting lost in the weeds (and so I don’t have to try to explain what a brain organoid is), the team found the microglia got infected at a much higher rate than other cells, likely causing the cells to behave abnormally or die altogether.

Why it matters:

Without properly functioning microglia, inflammatory substances can build up in the brain, leading to neural tissue damage, which can lead to neurological symptoms like those associated with long COVID.

The researchers say their findings suggest long COVID patients struggle to shake their symptoms due to a significant decline in microglia, and that anti-inflammatory drugs and drugs that suppress the function of substances released by microglia could be a treatment.

Big couple of weeks:

Three other COVID studies came out in the past couple weeks that I want to mention briefly:

First, a new study by researchers at UTHealth Houston found people infected with SARS-CoV-2 may experience changes to their genome structure that could explain the immunological symptoms experienced after infection and may also play a role in the development of long COVID.

• The team hopes the findings will “pave the way” for further research to help understand the impacts of long COVID.

After the UTHealth study was published, an international team of researchers shared a preprint (which means the study is yet to be peer reviewed) that found the SARS-CoV-2 spike protein accumulates in the brain after infection and “could have a long lifetime in the body” (other studies have suggested the spike protein can linger for up to 12 months after infection).

• The team thinks the accumulation and persistence of the spike protein could help explain some of the symptoms associated with long COVID.

Finally, a day after the preprint came out, a team of researchers at the University of Miami published the first study documenting brain injuries in newborns infected with SARS-CoV-2 via their mother’s placenta.

• Two newborns at the Holtz Children’s Hospital at the University of Miami tested negative for the virus, but had significantly elevated levels of the SARS-CoV-2 antibodies in their blood, indicating either the mothers or the babies had been infected at some point. Both newborns had seizures, small head sizes, and developmental delays, and one infant died after 13 months.

• After investigation, the team found the virus had entered the babies through their mothers’ placenta, damaging the newborns’ central nervous systems and interrupting a placental hormone important for brain development.

• The researchers say the study presented rare occurrences, as they’ve seen hundreds of other COVID-positive births and these were the only two devastating brain injuries.

Where we’re at:

No matter what we may like to think, COVID is certainly not over.

The U.S. Centers for Disease Control and Prevention reported nearly 121,000 new cases for the week ending April 5, and the latest data from the World Health Organization confirmed over 711,000 new cases globally for the week ending March 27.

Both figures are improvements from the weeks prior, and significantly better than the peaks reached during the past winter, but we’re not out of the woods yet (“yet” he says with a dumb hopefulness).

Read this post on Medium here.