Frequently Asked Questions about COVID-19 — September 28, 2022

“Shared expectations lead to predictability.”

589. Australian studies show a variety of immunity factors may link to long-covid.

         QIs immunity a factor for those who contract long-covid syndromes?

         A:  A continuing worldwide concern continues over Covid-19 as we try to learn more about the causes and manifestations of long-Covid.  Long-Covid is the continuing chronic presence of debilitating illness affecting a variety of different organ systems in the body.   It doesn’t affect everyone who is infected by the Covid-19 virus, but some authorities have estimated that as many as 1 person will develop long covid in every group of 20 who were infected.  A recent report out of Australia looked at how Covid-19 affects the immune system.  The Australian affiliate of the ABC network reported that when you catch a virus, there will be one of three outcomes:

  1. Your immune system clears the infection and you recover (for instance, with rhinovirus, which causes the common cold.)
  2. Your immune system fights the virus into “latency,” and you recover with a virus dormant in your body (for instance with the virus that causes chickenpox, that later can emerge as causing shingles.
  3. Your immune system fights, and despite best efforts the virus remains “chronic,” replicating at very low levels.  This can occur for the hepatitis C virus.

But international evidence suggests changes to our immune cells after Covid-19 infections may have other impacts. It may affect our ability to fight other viruses, as well as other pathogens, such as bacteria or fungi.

Research in Australia has found Covid-19 alters the balance of immune cells up to 24 weeks after clearing the infection.  There were changes to the relative numbers and types of immune cells between people who had recovered from Covid compared with healthy people who had not been infected.

Another study focused specifically on dendritic cells — the immune cells that are often considered the body’s “first line of defense.” Researchers found fewer of these cells circulating after people recovered from Covid. The ones that remained were less able to activate white blood cells known as T-cells, a critical step in activating anti-viral immunity.

Other studies have found different impacts on T-cells and other types of white blood cells known as B-cells (cells involved in producing antibodies).

After Covid-19 infections were cleared, one study found evidence many of these immunity cells had been activated and “exhausted.” This suggests the cells are dysfunctional and might not be able to adequately fight a subsequent infection. In other words, sustained activation of these immune cells after an infection may have an impact on other inflammatory diseases.

One study found people who had recovered from Covid-19 have changes in different types of B-cells. This included changes in the cells’ metabolism, which may impact how these cells function. Given B-cells are critical for producing antibodies, we’re not quite sure of the precise implications.

Having a healthy immune system and being vaccinated are critically important to have the best chance of fighting any infection, according to the CDC.

What impact will these changes have?  One of the main concerns is whether such changes may impact how the immune system responds to other infections, or whether these changes might cause or worsen other chronic conditions.

It is reassuring to know that scientists are working on a better understanding of long-Covid syndromes.  It is concerning to know how complicated the causes between a viral infection and the possible subsequent emergence of different chronic conditions.  It is also frustrating not being able to link the causation between Covid-19 and the subsequent possible development of chronic conditions.  A person diagnosed with diabetes weeks or months after recovering from Covid-19 can easily assume these two events are not related.

In the absence of scientific evidence, most experts advise continuing caution when gathering in groups (masks, social distancing and ventilation), The popular feeling of security may not actually be representing reality by failing to recognize the possibility of long-Covid.