As the world awaits the imminent arrival of one — or several — types of vaccines for COVID-19 to be administered, many people may wonder how important vaccines actually are to safeguarding public health. In this feature, we answer that question by looking at what vaccines have done for us throughout history.
THE ANCIENT PRACTICE OF VARIOLATION
Vaccines work by exposing the immune system to a very small amount of a virus or “information” about a virus — enough to “teach” it to recognize and react to that pathogen. This idea of exposing the body to a virus in a controlled way to “train” it to prevent infection is by no means a modern conception. Already in the 1500s, Chinese and Indian physicians practiced inoculation against the variola virus, which causes smallpox.
In Europe, Lady Mary Wortley Montagu introduced the inoculation process known as “variolation,” in the early 18th century. From 1716–1718 she travelled across Europe to Constantinople, present-day İstanbul, where she learned about variolation. Impressed by the evidence of its effectiveness, she continued to advocate for the procedure on her return to Britain.
Then in 1796, English physician Edward Jenner discovered that exposing people to small quantities of the cowpox virus, called “vaccinia” or the “vaccine virus,” was safer than the variola virus that infects humans. The cowpox virus was also effective in preventing smallpox. Thus, inoculation against the “vaccine virus” eventually became the umbrella term that we use today: vaccination.
HOW ARE VACCINES MADE?
There are basically four ways to make a vaccination by using:
- Weakened form of the virus
- Weakened form of the virus don’t reproduce well in the body. The body can still recognize that there is a virus present, so antibodies are formed to fight it. However, vaccines like these that use actual viruses are not given to people who have a weakened immune system.
- Inactive form of the virus
- This is a virus that has been inactivated chemically. Polio, hepatitis A, influenza, and rabies vaccines are made this way. The inactive virus can be detected by the body and generate cells to fight the active one. This type of vaccine can be given to people who have a weakened immune system.
- Part of the virus
- In some vaccines, only a part of the virus is used, specifically the protein that lives on its surface. Vaccines that use a part of the virus to build immunity include hepatitis B, human papillomavirus, and shingles.
- Part of the bacteria causing the virus
- Viruses that start with bacteria include diphtheria, tetanus, and pertussis. The bacteria produces a toxic protein that causes people to get sick. To make the vaccination, the toxin is deactivated so it can no longer cause disease but is still recognized by your body. By using the inactive toxin as the vaccination, your immune system can make the antibodies to prevent infection.
A developed vaccine must then go through testing and trials. Testing in the lab comes first. When the lab deems the vaccine safe, it goes through clinical trials with people who volunteer to take the vaccination. The vaccine is then tried on thousands of people to determine if it is safe.
WHAT IS USUALLY INJECTED INTO THE BODY DURING A VACCINATION?
The active ingredient in a vaccine is usually made of the viral or bacterial pathogen itself. There are two different approaches to this, with the pathogen being either alive or inactivated. Vaccines that incorporate living bacteria or viruses are called live attenuated vaccines. The pathogen is weakened to prevent it from causing the disease, but it is still able to elicit a strong immune response. Live attenuated vaccines work very well, but they are not suitable for everyone. If a person is immunocompromised, they may contract the very disease from which the vaccine should be protecting them.
Many types of vaccines, therefore, use an inactivated version of the active ingredients, which can take the form of the whole bacteria or viruses that have been killed. However, most vaccines are actually acellular, which means that they do not contain the whole pathogenic organism. They are actually made from the pathogen’s protein or sugar molecules. Our bodies recognize these molecules as foreign and mount an immune response.
WHAT VIRUSES DO WE HAVE VACCINES FOR?
Diseases you almost forgot about thanks to the different types of vaccines are:
- Hepatitis A
- Hepatitis B
- Hib (Haemophilus Influenza Type B)
- Pneumococcal Disease
- The Flu (Influenza)
- Whooping Cough (Pertussis)
WHAT ARE THE MANDATORY VACCINES IN THE US?
- Diphtheria, tetanus, and pertussis (DTaP)
- Haemophilus Influenza type B (Hib)
- Hepatitis A & B
- Meningococcal Disease
- Pneumococcal Disease
- Seasonal Influenza (Flu)
WHAT ARE THE NECESSARY VACCINES?
Every year, the Centers for Disease Control and Prevention (CDC) publish a recommended vaccination schedule for the whole country. The schedule is put together by a panel of 15 experts known as the Advisory Committee on Immunization Practices (ACIP). This schedule provides protection for everyone starting with the very first vaccine given the day you’re born.
For school-required vaccines, each state makes its own list of what vaccines are needed. As a result, vaccine mandates vary widely throughout the country but often incude:
- Chickenpox (varicella) vaccine
- Diphtheria, tetanus, and pertussis vaccine (DTaP)
- Hepatitis A vaccine (HepA)
- Hepatitis B vaccine (HepB)
- Hib vaccine
- Human papillomavirus (HPV) vaccine
- Influenza vaccine
- Measles, mumps, and rubella vaccine (MMR)
- Meningococcal vaccines
- Pneumococcal vaccine (PCV)
- Polio vaccine (IPV)
- Rotavirus vaccine
DEBUNKING THE ANTI-VACCINATION MYTH
Some people believe that there is little benefit in giving children vaccinations because the risk of contracting vaccine-preventable diseases is so low. This is a harmful anti-vaccination myth. Vaccine-preventable disease rates have dropped because immunization is now a widespread and common practice. In recent years, however, the number of people contracting vaccine-preventable diseases has increased. Research has found that children who do not undergo immunization are a contributing factor to this troubling trend. To prevent the spread of several diseases, it is vital that children continue to receive vaccinations.
Many types of vaccines have been heralded as the holy grail of disease prevention in the 20th and 21st centuries by reducing infant mortality and improving life expectancy worldwide. As we navigate the present COVID-19 pandemic, government officials, scientists and economists urge that the path forward hinges on the effectiveness of this current vaccine. Additionally, it is important to remind ourselves and loved ones on the importance of getting vaccinated during the flu season.
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