El poder de las vacunas en la prevención de enfermedades graves

Title: The Power of Vaccines in Preventing Severe Diseases Author: Scientific Dissemination Team of "How it Works". Reviewer: Sun Yifei, Director of the Office of Medical Education History at Hebei Medical University, Member of the Chinese Society of Medical History. Profile: Vaccines are crucial for preventing diseases and protecting human health. This article explains how they work and encourages their appreciation. Keywords: ['Immunology', 'Public Health']

In the intricate castle of the human body, the immune system serves as a loyal guardian. It is composed of billions of white blood cells, brave warriors that constantly patrol the organism, always ready to launch a fierce attack against invading pathogens. Once a tissue is threatened, the immune system quickly activates a two-pronged defense strategy. First, non-specific immunity acts as the first line of defense, rapidly suppressing the growth of pathogens to prevent their spread. Next, specific immunity, an even more powerful warrior, joins the battle, waging a death struggle against the pathogens.

Although the power of specific immunity is enormous, its implementation takes time. This is because each immune cell in the system can only fight one specific antigen. When the body faces a new pathogen, the specific immunity must start from scratch, searching for and training effector cells capable of confronting that pathogen. This process typically takes about 5 to 7 days, and during this time, the disease can sometimes become exceptionally severe.

However, the advent of the vaccine completely changed this situation. The vaccine, this clever preventive measure, allows the immune system to be fully prepared before the disease arrives. It contains inactivated, attenuated, or subunit antigens, as well as adjuvants, which can stimulate the immune system's alertness, leading it to initiate a preemptive strike. By coming into contact with some of the vaccine's antigens, the immune system can quickly find and train the corresponding memory cells, adequately preparing for future battles.

The vaccination process is like a drill. Although most effector cells produced during vaccination will disappear shortly after, there are always some that can survive and transform into "memory B cells" and "memory T cells." These memory cells remain in the lymphoid tissues for years or even decades, maintaining continuous vigilance against specific antigens. Once a real infection occurs, these memory cells can respond rapidly, activating and proliferating into a large immune army within 24 to 48 hours, eliminating the pathogen before it can cause severe consequences. It is precisely this amazing function of vaccines that allows us to be protected from diseases.

The World Health Organization (WHO) is very aware of the importance of vaccines, which is why it recommends that all individuals get vaccinated according to regular immunization programs. These vaccines can provide us with comprehensive protection against various common infectious diseases.

The World Health Organization (WHO) recommends that each person be vaccinated with the vaccines from the routine immunization program.

Some may ask, are vaccines really safe? Facts speak louder than words. Without current vaccination programs, up to 3 million children would lose their lives to diseases every year. By increasing vaccination rates, we hope to save more children's lives, with this number potentially reaching 2 million. However, in some areas, the decrease in vaccination rates has severely impacted the effectiveness of herd immunity. For instance, in the UK, the vaccination rate for the measles-mumps-rubella (MMR) vaccine was only 91.2% between 2017 and 2018, far below the 95% herd immunity threshold required to prevent outbreaks. This has provided the virus with an opportunity to spread among the population.

In recent years, the measles vaccination rate in the United States and Europe has declined, leading to outbreaks of the disease.

In the face of these difficulties, we must firmly debunk myths surrounding vaccines. Vaccines do not weaken or overload the immune system, even in the case of babies and premature infants. Vaccination is safe even in situations of mild discomfort or minor allergies, and there is no causal relationship between vaccination and the development of autism spectrum disorders.

To design more effective and safer vaccines, scientists around the world are working tirelessly. Among them, the "Human Vaccine Project" brings together leading scientists dedicated to unraveling the secrets of the immune response. At the same time, the "Human Immunomics Initiative" is identifying those genes that enable the immune system to produce antibodies against various antigens, providing valuable information for the design of future vaccines. On the other hand, the "Immunity Rules Project" explores the rules governing how the immune system establishes defense mechanisms and remembers past infections, aiming to better utilize these rules to combat diseases.

It is worth mentioning that the influenza virus undergoes antigenic drift every year, so we need to continually adjust vaccines to address new challenges. This flexibility is key to vaccines being able to continuously protect us from influenza.

When reviewing history, it is not difficult to notice the brilliant achievements that vaccines have accomplished in saving lives. On May 14, 1796, eight-year-old James Phipps became the first person in history to receive the smallpox vaccine, a milestone that marked a significant advance in humanity's fight against this disease. Before the advent of vaccines, many children paralyzed by polio could only rely on a "iron lung" to maintain their breathing, and their fate was extremely tragic.

Before the advent of the vaccine, children suffering from muscle paralysis due to poliomyelitis depended on "iron lungs" to maintain their breathing.

Today, vaccines have helped us eradicate smallpox, a horrible disease that used to claim 2 to 3 million lives a year. It is the only infectious disease that has been completely eradicated, an achievement that demonstrates the tremendous power of vaccines. Additionally, vaccines have played a significant role in preventing diphtheria, whooping cough, measles, and neonatal tetanus, among others. Each year, millions of lives are saved thanks to vaccines, which undoubtedly prove that vaccines save lives.

So, what happens in our body when we get vaccinated? The antigens in the vaccine, which are components of the pathogen in forms like live attenuated viruses, inactivated viruses, subunit vaccines, or toxoids, enter our organism. These antigens are phagocytosed and processed by antigen-presenting cells (APC), allowing their epitopes to be clearly presented to other immune system cells. Next, lymphoid cells known as B and T cells approach to examine these antigens, and through a process of clonal selection, identify the cells capable of combating these infections. Once the appropriate lymphocytes are found, they are trained to become effector cells that can resist the infection, a process that takes approximately 5 to 7 days. Some of these lymphocytes will become memory cells, which remain in the lymphoid tissues for years or even decades, waiting to respond rapidly if the same infection reoccurs.

When a real infection occurs, the immune system is already fully prepared. Memory cells can quickly recognize the antigens and activate the secondary immune response. Before we even notice the infection, the immune system has already eradicated the pathogen in one swift blow. This is the power of vaccines, allowing us to face the threat of diseases with peace and confidence.

The images in the text are from the magazine "How it Works".