The Paradox of Immunity: Why We Fall Victim to Every New Virus [Reading Science]

Students wearing masks at a high school in India washing their hands before attending class to prevent the novel coronavirus infection (COVID-19).
[Photo by AFP/ Yonhap News]

[Asia Economy Reporter Kim Jong-hwa] Humans encounter numerous pathogens in daily life. These pathogens enter the human body through contact with food, breathing, and other means. However, even though many pathogens enter the body, it does not necessarily mean that one will get sick. This is because there is an immune system that defends against pathogens and protects the body.

Immunity is the function by which the human body defends and protects itself against foreign substances or pathogens. But why is it that humans cannot escape a pandemic whenever a new virus appears?

Is it really because the human immune system is inferior to that of bats, the hosts of the 'Severe Acute Respiratory Syndrome Coronavirus 2 (COVID-19)'? In the article [Humans Inferior to Bats?], we examined that all vertebrates, including humans, produce a protein called 'interferon' which has immune functions.

Humans and most other animals produce interferon when an individual is infected by a virus, but bats continuously produce interferon in their cells even without viral infection. Therefore, it was pointed out that the immune system of bats might be superior to that of humans or other animals.

Bats are animals with an amazing immune system that, despite being hosts to most viruses that have recently caused pandemics, do not get infected by these viruses themselves. Although humans and bats cannot be directly compared, the reason humans fall into pandemics whenever new viruses emerge is due to the 'specificity of the antigen-antibody reaction' in humans.

Humans receive 'vaccines' to defend against pathogens. However, we do not receive just one vaccine; we receive different vaccines depending on the type of disease. Is it impossible to prevent all diseases with a single vaccine? One vaccine protects against one disease. This characteristic of human immunity is called the specificity of the antigen-antibody reaction.

Antibodies have regions that recognize antigens and can only bind to antigens that fit those regions. For example, hepatitis A antibodies can bind to the hepatitis A virus and neutralize it, but they cannot bind to other viruses such as pneumonia or measles. In other words, they are helpless against other viruses.

Vaccination introduces a vaccine, which is a non-toxic or weak antigen, into the body. Then, T lymphocytes with toxicity inside white blood cells recognize the infected virus and attack to eliminate it. During this process, T lymphocytes proliferate, and B cells, another type of lymphocyte in white blood cells, memorize this virus, i.e., the 'antigen.'

Later, if the same virus invades, B cells immediately recall it and produce antibodies to respond. This immune system is why people rarely get sick from diseases they have had before.

Amid the implementation of the five-day rotation system for public masks, citizens are seen lining up in front of a pharmacy in Mapo-gu, Seoul on the 15th to purchase masks.
[Photo by Kang Jin-hyung, Asia Economy]

However, the coronavirus is one of the common cold viruses found in humans and animals, but it mutates frequently, causing it to be recognized as an antigen unknown to B cell memory. Just like with SARS or MERS, new vaccines must be developed each time.

Is it possible to neutralize all viruses with a single vaccine? This is the ideal of all scientists and the dream of humanity. This is why scientists continue to study bats, the hosts of all viruses, despite the risks of infection.

Many people overcome the coronavirus without vaccines. The coronavirus is said to be vulnerable to heat. Drinking warm beverages rather than cold drinks and keeping the body warm to prevent a drop in body temperature are as important as wearing masks or washing hands.

Each disease requires its own appropriate vaccination. This means that not only children but also adults should not avoid timely vaccinations emphasized by health authorities using excuses of inconvenience.