What You Need To Know About Vaccines

Before the invention of vaccines, how did we survive infectious diseases? The truth is, we often didn’t. According to the WHO, vaccines have saved more human lives than any other medical invention in history. There are several deadly diseases that many people today have no idea existed, all thanks to vaccines. 

How Do Vaccines Work?

To understand how vaccines work, you need to understand how your immune system functions. The immune system is a complex network of cells and organs that help the human body fight pathogens. It all starts with physical barriers like our skin, hair, and mucus, which keep these pathogens out of our bodies. When pathogens break through these defenses, our bodies react with antibodies, which are like the immune system's soldiers.

Pathogens have components called antigens. When encountered, antigens trigger the immune system to produce specific antibodies that eliminate the pathogen. The immune system also creates memory cells, which remember how to quickly defeat the pathogen if it invades again.

Vaccines are usually made from weak or inactive parts of a pathogen, including its antigen, to help the immune system produce antibodies. These vaccines cannot cause the disease because the antigen is very weak or dead. Repeated vaccine doses enhance this immune response, ensuring long-lasting protection.

Newer vaccines today contain the blueprint for producing antigens instead of the antigen itself. However, they still stimulate the same antibody-producing response.

Types of Vaccines

Inactivated Vaccines
Inactivated vaccines contain a killed pathogen. The pathogen is grown in the lab and then killed to ensure it cannot cause disease. This type of vaccine stimulates antibody production but is not as strong as live vaccines, so multiple doses (booster shots) may be needed over time to ensure protection. Examples include Hepatitis A, Rabies, and Polio vaccines.

Live-Attenuated Vaccines
Live vaccines contain a weakened form of the pathogen. They create a strong and long-lasting immune response similar to the infection they are preventing, without causing the disease. Typically, one to two doses provide lifetime protection. However, live vaccines may be contraindicated for people with weakened immune systems, such as those on immunosuppressive medications, with cancer, or following an organ transplant. Examples include Chickenpox, Measles, Smallpox, and Rotavirus vaccines.

Messenger RNA (mRNA) Vaccines
mRNA vaccines use the pathogen's genetic code, allowing for faster production. These vaccines teach the body to make a protein unique to the virus, triggering an immune response without causing illness. Examples include the Pfizer and Moderna COVID-19 vaccines.

Subunit Vaccines
Subunit vaccines contain parts of the pathogen, such as its protein, sugar, or shell, rather than the entire pathogen. These vaccines generate a strong immune response and are suitable for people with weakened immune systems or chronic health conditions. However, booster shots may be needed. Examples include Hepatitis B, Whooping Cough, and Shingles vaccines.

Toxoid Vaccines
Toxoid vaccines contain toxins produced by the pathogen. They trigger an immune response to the toxic parts of the pathogen, not the whole pathogen. Booster shots may be needed for ongoing protection. Examples include Tetanus and Diphtheria vaccines.

Viral Vector Vaccines
Viral vector vaccines use a harmless virus to deliver the gene of the pathogen your immune system needs to fight. Examples of viral vectors include the Measles virus, Adenovirus, and Influenza virus.

Benefits of Vaccines

Protection from Preventable and Potentially Life-threatening Diseases
Vaccines significantly reduce the likelihood of contracting life-threatening diseases and can lessen the severity of the disease if it does occur. They protect not only the person vaccinated but also help prevent the spread of the disease to others.

Cost-effective Intervention
Treating diseases that can be prevented by vaccines is costly. Even mild cases can affect productivity, employment, and daily activities. Vaccines save money by reducing medical costs and minimizing downtime from illnesses, making them a cost-effective public health intervention.

Herd Immunity
Young children, the elderly, and people with weakened immune systems are at higher risk for diseases. Widespread vaccination can drastically reduce disease circulation and even eliminate some diseases. Studies show that when enough people are immune to a disease, it protects those who are still vulnerable, a phenomenon known as herd immunity.

Safety
Vaccines undergo thorough testing. Before recommending vaccines, the CDC and other experts monitor and review their safety. While some people may experience mild side effects, these typically resolve on their own within a few days.

Potential Side Effects of Vaccines

People may experience a few side effects after getting a vaccine. However, they are often mild and last only a few days. Some of the side effects of vaccines include:

• Soreness at the injection site
• Feeling sick or having a high temperature
• Feeling faint
• Headache
• Flu-like symptoms

It is important to note that allergic reactions to vaccines are rare. However, if they do happen, it is usually within minutes of receiving a dose. Inform your doctor immediately if you have an allergic reaction to a vaccine.

The information provided in this article is for educational purposes and should not be considered medical advice. Consult with your healthcare provider to discuss your specific health needs and vaccine recommendations.

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Sources:
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1. WHO | Coronavirus disease (COVID-19): Herd immunity, lockdowns and COVID-19
2. CDC |  Vaccine Safety Monitoring