Let’s compare a very old disease to a very new one. You might be thinking this is in the line of “Oh, what a terrible scourge this could be” Not! This is about the immune system, and exploding some popular ideas about it.

Differences

• Tuberculosis (TB), which has existed for at least 17,000 years, was the leading bacterial cause of death in 2014. COVID-19 jumped species no more than six months ago.
• The infectious agent of tuberculosis is a bacteria, a kind of living cell. COVID-19 is caused by a coronavirus, a non-living package of malevolent instructions for the machinery of a cell, with a misleading label on the box.

Similarities

• Only 10% of persons exposed to TB get the disease. This corresponds to the huge preponderance of asymptomatic COVID-19.
• Both TB and coronavirus have tricky strategies to evade the immune system long enough to reproduce and infect more people. Unlike most bacteria, which live next to human cells, and in bodily fluids, mycobacterium tuberculosis must inhabit a human cell to survive.  Hidden within a cell, it is almost invisible to circulating antibodies. On the surface of the lung lining, COVID-19 is shielded from large antibodies.

Many COVID-19 cases, including those who recover, show weak antibody response. The coronavirus does not share anything of detail with tuberculosis, but the result is the same: stealth. COVID-19 may take advantage of barrier membranes in the lung to avoid circulating antibodies.

The antibody response to TB is also weak, wrong, or nonexistent. Quoting from (NCBI/PMC) Emerging Themes for the Role of Antibodies in Tuberculosis [brackets mine],

The best way to debunk a scientific dogma is to throw irrefutable evidence at it….the tide of the opinion has begun to turn in favour of Abs [antibodies] but we also caution against…

Thus, the strongest argument that Abs do not contribute to protection against TB comes from numerous preclinical vaccine studies showing strong Ab responses but minimal or no protection;

Both TB mycobacterium tuberculosis and coronavirus can persist in the body. The TB bacillus was isolated in 1882. By 1939, it was thought that eventually, all the bacteria left in the lung of a recovered patient eventually die. It’s 2020, and we’re back to “nobody knows.” For both COVID and TB, there is no skin, blood, or culture test that definitively proves the pathogen (germ) is gone from the body.

Antibodies are a question, not an answer. From (NCBI/PMC) Latently and uninfected healthcare workers exposed to TB make protective antibodies against Mycobacterium tuberculosis (brackets mine),

Our results indicate that certain individuals make protective antibodies against Mtb [TB] and challenge paradigms about the nature of an effective immune response to TB. …

Although it was known that both active TB patients and healthy subjects make detectable antibody responses to Mtb [TB](19–21), it was not known whether any of these antibodies afford direct protection against infection. … suggesting that protective antibodies isolated from our study are part of a complex interplay between the pathogen [germ] and host immune system and highlighting a protective role.

From (NCBI/PMC) Antibodies and tuberculosis,

The discovery of individuals in high-exposure settings that do not have a detectable T-cell response to M.tb antigens by tuberculin skin testing (TST) or ex vivo stimulation has triggered interest in the search for individuals with unusually effective immune responses against TB [42]

Takeaway #1: The expert picture is more confused than the popular, which grabs onto oversimplification.

Takeaway #2: Antibodies have been exaggerated in popular media, which view them as the body’s main defense from disease. In many cases, they are secondary to other processes by which the body fights disease. Any time we are looking at antibodies, they might be the:

• Wrong ones, created by error, attacking the body’s own tissue.
  
• Useless, diverting the body from effective response. The tuberculin skin test may be an example.
• Useful in moderating disease severity, by preventing spread from one tissue compartment of the body to another, such as the blood.
• Secondary means by which the body fights the disease.
• For some diseases, effective prevention and cure.

Takeaway #3: TB and COVID use different tricks to hide from antibodies. As with TB,  even a weakly effective COVID-19 vaccine may be useful in ways yet to be revealed. Nota bene: This cannot be predicted. It can only be observed.

Besides the famous movie-star antibody, what other defenses does the body have? A hint of the puzzle: A partially effective vaccine against TB exists, which appears to have beneficial effects other than antibody production. New vaccine technologies offer possible diverse benefits. The body has another immune system, which we will get into shortly.

Clusters of asymptomatic cases suggest that with COVID-19, the personal and local biomes (the germs we live with) may be crucial.

To be continued shortly.