The truth about vaccines

The Truth About Vaccines And Immunizations | Everything You Should Know (5 Powerful types of vaccines)

The Truth About Vaccines | Vaccine Definition | vaccines pros and cons | The importance of vaccines (A simplified overview)

The truth about vaccines - girl taking a vaccine

Vaccine definition and the truth about vaccines

By definition, a vaccine is a biological preparation that provides active immunity to a specific infectious disease. Typically, a vaccine carries a biological preparation from the targeted microorganism or a synthetically preparation that resembles to it. Vaccines could be used as prophylactic agents, to prevent or ameliorate an infection with a certain disease, or as therapeutic agents, to fight occurred diseases such as cancer.

Vaccination is a secure, easy and powerful method to defend towards harmful sicknesses. It helps in developing immunity against infectious diseases before encountering them by using the body’s natural defenses to build resistance and become stronger. Vaccination is the most effective technique to prevent infectious disease. It’s known that widespread immunity acquired due to vaccination was worldly responsible for the eradication of smallpox, polio, tetanus, and measles in most areas.

Different types of Vaccines were proven powerful against a large number of infections. The World Health Organization (WHO) reports that certified vaccines are present for twenty-five preventable infections like influenza vaccine, the chicken pox vaccine and the HPV vaccine. Those types of vaccines are estimated to save up to 3 million lives every year.

In this article you will learn more about the different types of vaccines, vaccines pros and cons and vaccine alternatives.

The importance of vaccines ?

The body’s first line of defense against microorganism include chemical and physical barriers such as the skin, the stomach acidity, the mucous membranes… In addition to those barriers, vertebrates developed a complex network of organs, tissues and cells that coordinate to defend the body against infections. It’s called the immune system.

Immune system include primary lymphoid organs (bone marrow and thymus) were the immune cell are produced , and secondary lymphoid organs (spleen, tonsils, lymph nodes) were the immune responses are started and regulated. Those organs are shown in the figure below. 

Immune cells are the white blood cells existing naturally in many forms: Granulocytes, Mast cells, Monocyte, Dendritic cells, Natural killers, Lymphocytes…

Those cells work altogether in a complex network of signals and interaction to ensure an effective defense against infections. When encountering a microorganism, the immune system is alerted by some of its molecules (proteins, specific sugar compositions, toxins…). Those molecules that are responsible of inducing an immune response are called antigens.

Two major types of immune responses exist: the innate immune response and the adaptive response. The innate immunity is non-specific for the antigen (the body reacts the same way to defend against all microorganisms), the adaptive immunity, in another hand, is more developed and antigen-specific and more importantly: it develops an immunological.

In the case of the adaptive immunity, the body specifically recognizes the antigens of a microorganism and conduct a response that leads to its deterioration by specific activated lymphocytes. This process leads to the production of what we call antigen-specific memory. It consists of a group of lymphocytes that targets specifically this microorganism and that are activated to alert the immune system in case of encountering the same microorganism again.

When encountering an antigen for the second time, the immune response is stronger, faster and way more effective. That’s what immunologists call a secondary response. The whole purpose of vaccination, is to build an immunological thus ensuring a strong, specific and fast elimination of pathogen. 

vaccine in lab - vaccines pros and cons

What are the requirement for a good vaccine?

1. The identification of the most appropriate antigen

The following requirements help in developing the most active types of vaccines and explain the reasons behind the failure of a certain vaccine. As discussed previously, an antigen is a pathogen molecule able to induce the immune system.  Each pathogen have millions of molecules, the identification of the most appropriate antigen can be a hectic work for an immunologist. Usually scientists are looking for a molecule that is specific for the pathogen and that is expressed regularly by the microorganism. It’s a crucial step to ensure the success of the vaccine.

2. The induction of the innate immune response

An effective vaccine should trigger a complete immune response. It should induce an innate as an adaptive immune response. The innate response is the first line of defense against a microorganism. It stimulates and activates the adaptive immunity through specific interactions. A vaccine that does not induce innate immunity could be useless and prone to failure.

3. The selection of targeted cells

We have many types of immune cells working in coordination to ensure the better protection. But, it’s important to highlight the fact that some cells are more involved in some lines of defense more than others. Each category of pathogens is eliminated through specific pathways. To ensure the success of a vaccine, immunologists study these responses and target the most adequate and major response to eliminate the pathogen.

Vaccine injection - types of vaccines

What are the different types of vaccines?

To date many types of vaccines are present. Each type is designed to target a specific type of germs infections by creating an adequate resistance to fight them. In order to choose the best vaccine type, scientists consider many points: the immune response facing the microorganism, the targeted population that should be vaccinated, and the most suitable technology to establish this vaccine.

The different types of vaccines are :

1. The live-attenuated vaccines

These vaccines include an attenuated form of the microorganism that causes the infection. Those vaccines are very similar to the natural infection thus creating a strong immunological that last for many years. In general, a single dose of such vaccine is enough to create a lifetime protection against the pathogen. 

Those vaccines are commonly used to protect against Rotavirus, Chickenpox, Measles, Yellow fever and Rotavirus.

2. The inactivated vaccines

Those preparations include the killed version of the targeted pathogen. Contrarily to attenuated vaccines, these types of vaccines doesn’t mimic the natural infection and thus do not provide a strong immunity over time. Several booster shots are required to maintain the immunological and ensure the best resistance against the pathogen. Inactivated vaccines are used against the Influenza virus, the Hepatitis A virus, The Polio virus and the Rabies.

3. The subunit, recombinant, polysaccharide and conjugate vaccines

These vaccines use some structures of the pathogen (polysaccharides, proteins, capsid molecules…)

Those vaccines are safe and could be used by everybody. They produce a specific strong immunity against some parts of the microorganism. Those types of vaccines usually require booster shots and could offer a limited protection against new variants (mutations) having modified molecules. To date, those vaccines showed a high efficiency against the Hepatitis B virus, the Human Papilloma virus, the Haemophilus influenzae type b infection, Shingles, Pneumococcal and Meningococcal diseases, the Whooping cough…

The toxoid vaccines: Those vaccines use the toxin produced by the pathogen thus creating an immunity against the toxins causing the disease instead of the pathogen itself. Those vaccines also require boosting shots to ensure the best protection. To date, the most common toxin vaccines are the Diphtheria vaccine and the Tetanus vaccine.

4. The Heterotopic vaccines

In this category of vaccines, we use pathogens targeting other species to develop an immunity against similar pathogens targeting humans. The most known example is the Tuberculosis vaccine. In this case, we don’t use the Mycobacterium tuberculosis (causing the disease in humans) to prepare the vaccine; we use instead the BCG (another bacteria similar to the pathogen that is less harmful to humans). Those types of vaccines are widely criticized but still been used to prevent Tuberculosis pandemic breakthrough.

5. RNA vaccines

This preparation uses the messenger RNA to produce an adaptive immune response and create an immunological. This vaccine transfects the synthetic RNA into immune cells causing them to present a foreign protein. This mechanism mimic the natural presentation of foreign molecules on the immune cells that normally indicate a cancer growing or a virus infection. Such types of vaccines are designed to target virus infection and may be very interesting to prevent specific tumors growth.

RNA vaccines gained a huge interest recently since they were approved for emergency use by the food and drug administration against COVID-19 (Moderna and Pfizer–BioNTech COVID-19 vaccines). RNA types of vaccines were subjected to targeted misinformation that spread via social media, wrongly arguing that this vaccination technology could alter the person’s DNA. Such claims reflect the worries of the public ignoring scientific evidences accumulated from trials on thousands of patients.

Various approaches for Vaccine Development
mass vaccination - the importance of vaccines

The controversy around vaccines and the truth about Vaccines

When a person gets vaccinated, the risk of getting an infection is reduced thus the transmission of a certain pathogen is limited. Herd immunity is a term expressing an indirect protection of a certain population. We can reach herd immunity by the infection of a high percentage of the individuals (thus putting lives at risks and weakening the health services system) or by vaccination. In simple terms, herd immunity is reached when a pathogen is no more circulating in a certain population and the risk of getting this pathogen becomes very low.

Needless to say, that vaccination is the best way to achieve Herd immunity and create a safe environment for the general population. Vaccination helped achieving herd immunity for many pathogens: Polio, Tetanus, The flu, Hepatitis A and B, Rubella, Measles, Pneumococcal infections, Rotavirus, Mumps, Chicken pox, Diphtheria….

The majority of these infections were life threatening before reaching herd immunity through vaccination and saving millions of lives every year.

controversy around vaccines

The controversy around vaccines

The vaccination subject present a lot of controversy. Let’s start by claiming that the concerns about vaccination are perfectly legitimate since many side effects could be associated with vaccination. Many concerns have arisen due to a potential association of certain vaccines with the development of rare diseases. The most common example to date is the claims of the autism caused by the combined MMR vaccine. Even if a controversy on this point exists to date, there is no final evidence showing a significant increase in the autism rates in the vaccinated population through the years.

Vaccines Pros and Cons


  • Vaccines are great to prevent dangerous diseases that have killed and can sicken or kill many individuals.
  • Researchers thoroughly explore each vaccine before presenting the information to the U.S. Food and Drug Administration (FDA). The FDA can accept or reject the vaccine. The overwhelming majority of research shows that vaccines are safe.
  • Vaccines do not just protect you. They protect people around you, especially people who aren’t well enough to be vaccinated.


  • Each vaccine is created out of various parts, and each may impact you differently. Individuals who have experienced allergic reactions to certain vaccines previously might experience an allergic response.
  • You could still get ill, even when you’re vaccinated.
  • Some individuals with weakened immune systems cannot be vaccinated or only under the close supervision of a healthcare provider.
covid-19 vaccine - alternatives to vaccines

Additional notes: The COVID-19 vaccines

2 vaccines are authorized and recommended in the US: The Pfizer-BioNTech COVID-19 vaccine and the Moderna’s COVID-19 vaccine.

Other vaccines are still in the phase 3 of the clinical trials: the AstraZeneca’s COVID-19 vaccine, the Johnson & Johnson’s COVID-19 vaccine, the Sputnik V, the Novavax’s COVID-19 vaccine…

Both Pfizer and Moderna vaccines are RNA vaccines, authorized for use for people who are above 16 years old, are administered through two shots, which efficiency is around 95% after the second shot , and are equally efficient among different racial and ethnic groups.  The interval between Moderna doses is 28 days; for the Pfizer vaccine, it’s 21 days.

AstraZeneca’s vaccine and Johnson & Johnson’s vaccine are both viral vector vaccines that are expected to seek FDA approve in February 2021. AstraZeneca’s vaccine is also administered by a double shot which efficacy is 76% after the first dose and 82% after the full two doses. Although Johnson & Johnson’s vaccine is a single dose vaccine with an efficacy of 85%. Novavax vaccine’s efficiency is estimated by 89% and Sputnik V’s one by 92%.

Other vaccines are also studied and many approaches used.  It’s important to mention that the governments are choosing to contact with a company or another and thus buy their vaccines. The individuals don’t have to date the luxury to choose the vaccine they prefer. 

Is There Any Alternatives To Vaccines?

There are some alternatives to Vaccines, The World Health Organization (WHO) has established a worldwide trial of medication which may be used to deal with individuals who have COVID-19. Here are five potential coronavirus remedies that WHO has been exploring.

1. The enzyme inhibitor

Remdesivir is the frontrunner from the trial. It was initially developed by US biotechnology company Gilead Sciences to deal with Ebola. It inhibits an enzyme known as RNA-dependent RNA polymerase’ that viruses will need to replicate.

Research in 2017 revealed it could inhibit the SARS and MERS coronaviruses. The first COVID-19 individual in the US has been granted remdesivir when his condition deteriorated. There is A case report from the New England Journal Of Medicine explained that his state rose the following day.

2. The malaria medicine

Chloroquine and hydroxychloroquine are just two medications usually utilized to treat malaria and, among other ailments, rheumatoid arthritis. There were reports from China which chloroquine was a powerful remedy for COVID-19, and a trial of hydroxychloroquine in France revealed it decreased amounts of this virus from nasal swabs.

But a lot of virologists are careful, pointing out that hydroxychloroquine was studied as an antiviral for years, but trials haven’t worked out.

3. The HIV treatment

Ritonavir and lopinavir is a mixture medication -both are given jointly – and it is already utilized to treat HIV infections. It works by blocking a kind of enzyme known as a protease, which can be used when new viruses are being constructed. It is proven to work with different viruses, also — such as coronaviruses.

A trial in Wuhan, China, did not fare well, together with all the sufferers not performing better than those not given the medication. However, the physicians involved stated that the patients given the medicine might have been too sick to gain.

4. The drug cocktail

One mix of medication joins the antiviral HIV medications, ritonavir and lopinavir, and interferon beta. This protein modulates inflammation within the human body and is used as a treatment for multiple sclerosis.

This mixture has been tested in Saudi Arabia as a remedy for the coronavirus which causes MERS. Another trial, between University of Southampton investigators, examines interferon-beta by itself at COVID-19 hospital patients in the united kingdom.

5. The plasma injection

While not a part of the WHO trial, the thought behind convalescent serum is straightforward. Individuals who have recovered from COVID-19 will have generated antibodies to fight the virus off. Why don’t you take some of their blood, divide the plasma that comprises the antibodies, and inject it to COVID-19 patients?

The convalescent serum has been used to deal with SARS and MERS. The US Food and Drug Administration (FDA) has accepted a trial from COVID-19 in dozens of hospitals across the USA.


Vaccination is an essential tool to achieve Herd immunity and prevent further propagations of infectious disease. It aims to develop a resistance against a pathogen and create an immunological. Scientists, applying the knowledge of fundamental immunology and molecular technology, developed different types of vaccines each responding to the natural physiology and the health system requirements. Emphasizing on the importance of vaccines. Vaccination save lives! Everybody needs to realize it!

In case you sill have any questions about types of vaccines or vaccines pros and cons, let us know in the comment section.

Important Sources:

Comparison of new vaccine approaches Covid 19 via European Pharmaceutical Review

Different Vaccines via Center of Disease control and prevention CDC

How do vaccines work via World Health Organization WHO

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Najat Bteich
Najat Bteich is a researcher in cellular biology and an expert in the field of regenerative medicine and pharmacology. She graduated from the Lebanese University with a Master degree in “Stem cells, organogenesis and regenerative medicine” and pursued a researcher career in cellular biology and bioengineering projects between the Lebanese University, The American University of Beirut, and The University of Rouen.
Articles: 4

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