What Causes Long Covid?

Summarising here the key points from the article in "What causes Long Covid? Scientists are zeroing in on the answer" by Yasmin Tayag.

“I am quite optimistic that there will be things that will be helpful. We’re not going to rest” - Dr Resia Pretorius

Early suspects as to the cause of Long Covid included:

Early research is pointing to factors that may raise a person’s risk of Long Covid, such as:

  • low levels of certain antibodies

  • reactivated viruses in the bloodstream

  • existing conditions such as diabetes or asthma.

Later research has identified risks as being:

  • higher levels of SARS-CoV-2 RNA in the blood in the early stages of infection

  • Type 2 diabetes

  • reactivated Epstein-Barr virus

  • the presence of certain autoantibodies.

Possible risk factors could be:

  • low levels of the antibodies IgM and IgG3

  • pre-existing asthma

Vaccination against Covid-19 appears to offer some protection against Long Covid but it isn't clear how much. Possible benefits are:

  • it certainly helps by preventing serious illness/death/hospitalization

  • it may help clear the virus before it can lodge in the body for the long term

  • it spurs the immune system to specifically target the virus, rather than raise defenses throughout the whole body, which could cause collateral damage elsewhere.

In April 2021 the leading 5 possible mechanisms of Long Covid were:

  1. Viral persistence - the virus and “viral ghosts” didn’t actually leave the body

  2. Virus reactivation - Covid-19 infection causes other viruses already in our body to awaken such as EBV, varicella zoster and Lyme

  3. Autoimmune disorder - otherwise known as "molecular mimicry". The virus interrupts normal immune function, causing it to misfire, so that molecules that normally target foreign invaders — like viruses — turn on the body

  4. Altered gut microbiome - this can lead to persistent inflammation throughout the body

  5. Body injury - damage to the organs such as the heart, brain and lungs.

According to this article they know feel there are 2 leading theories of why Long Covid exists:

  1. Dysregulation in the immune system (the immune theory)

  2. Persistence of the virus in the body.

-Please note both could be occurring together in Long Covid.

The Immune Theory

The immune theory suggests that Covid-19 turns the immune system against the body. This could explain symptoms like:

  • palpitations

  • dizziness

  • weakness

  • microclots in the blood

A large proportion of Long Covid patients have dysautonomia, a condition that interferes with processes like balance, heart rate, blood pressure, temperature, and digestion.

{With Yale University immunologist Akiko Iwasaki, Putrino is studying the blood of long-haulers for evidence of an abnormal immune response that might be throwing the autonomic nervous system off track}.

Flurries of microclots observed in the blood of people with acute and long Covid may be fueling the immune system’s reaction. Clots in healthy people usually break down easily, but those in people with long Covid resist digestion and continue to drift throughout the circulation. Dr. Resia Pretorius’s team has discovered inflammatory molecules concealed inside these microclots that she thinks may spur the production of autoantibodies. Having clots in circulation can cause the whole vascular system to become inflamed, ultimately choking off the supply of oxygen to cells and leading to a range of issues throughout the body.

This immune dysregulation will also allow the reactivation of dormant viruses such as EBV.

The Viral Persistence Theory

It has been shown that the virus can persist in the body and brain well after the acute infection and that genetic fragments of the virus has been seen to be present in the body for up to 230 days.

Viral reservoirs could:

  • continue to injury the body directly

  • cause viral proteins to leak into the bloodstream and cause microclots

  • activate the immune system leading to inflammation and further damage

  • trigger brain inflammation via the vagus nerve.

Research in ongoing into treatments. In this article they mentioned breath work for dysautonomia symptoms, developing diagnostic tools, possible vaccines and medications, and clot-busting.

Image : A line of people wait in the rain to be tested for Covid in Los Angeles, California, on December 29.Gary Coronado/Los Angeles Times via Getty Images

What causes long Covid? Scientists are zeroing in on the answer.

By Yasmin Tayag Jan 31 2022.

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