Monday 1 March 2021

Vaccine development and distribution


World Health Organization (WHO) says better health for everyone, everywhere. It is responsible for international public health. With the Current pandemic, WHO is ensuring good health for all. Various treatments and therapeutics for COVID-19 are evaluated rigorously and given a green flag for use with terms and conditions as necessary. 

A guest post by Aparna Rane

This article is focused on Vaccines as given in series by WHO. It is explained in six parts on vaccine development and distribution.

1) PART ONE: How do vaccines work?

2) PART TWO: How are vaccines developed?

3) PART THREE: Manufacturing, safety, and quality control of vaccines

4) PART FOUR: The different types of COVID-19 vaccines

5) PART FIVE: Access and allocation: how will there be fair and equitable allocation of limited supplies?

6) PART SIX: Country readiness for COVID-19 vaccines

1) PART ONE How do vaccines work?

The Human body has many systems for its protection. The protection can be from disease causing organisms, physical harm, or mental harm. The system that plays important role in protecting us from causing us any disease is the immune system. Pathogens are disease causing organisms which when enter our body, stimulates to produce antibodies to protect us. This antigen-antibody complex destroys the pathogen and stops the disease. While doing this it also produces memory cells. So in the future, when the body is exposed to the pathogen, the antibodies are formed again to protect the body.

Vaccines use this organism in various forms, but without disease causing ability of it and produces antibodies in the body. So in future, if the body encounters the real pathogen, the body will be ready to eradicate the disease with the help of the immune system.

Herd immunity helps the people who are unable to be vaccinated. The Link for the details is here

2) PART TWO: How are vaccines developed?

Vaccines developed are required to be safe. It contains antigen, preservatives, stabilizers, surfactant, Residual, diluent, adjuvant.

Each vaccine undergoes screening and evaluation. It has a preclinical and clinical trial stage. Preclinical stage in animals to evaluate the safety and potential to prevent disease. Clinical Trial stages in human with three phases

Phase I: small number and safety and immune response generation.

Phase II: several hundred volunteers to further assess its safety and ability to generate an immune response.

Phase III: thousands of volunteers – and compared to a similar group of people who didn’t get the vaccine.

After receiving results, regulatory bodies in each country closely review the study data and decide whether to authorize the vaccine for use. Post-approval continuous monitoring of vaccine safety and effectiveness is done. The Link for the details is here

3) PART THREE: Manufacturing, safety, and quality control of vaccines

After successful clinical trials, the production of vaccines is undergone in a very strict way. The quality, safety, and efficacy criteria are essential elements of a vaccine. Every country has its own regulatory requirements and standards set for it like WHO has Prequalification (PQ)assessment process. Also during a Global pandemic situation like the ongoing COVID-19 pandemic, the WHO Emergency Use Listing Procedure (EUL) may be used to allow emergency use of the vaccine. Also, various other procedures like USFDA EUA (Emergency Use Authorization) for vaccines are done as per the situation requirements.

Once the vaccine is produced, it is quality checked and bottled in glass vials, as they are durable and maintain integrity. They are stored as per the requirement and transported globally with utmost care. The Link for the details is here

4) PART FOUR: The different types of COVID-19 vaccines

Various companies are involved in different types of vaccine manufacturing. Many vaccines to date have received Emergency Use approval based on their clinical trial data study. These vaccines are continuously monitored for safety and efficacy since corona variants are also emerging with time.

The different types of vaccines are

a) they use a whole virus or bacterium;

b) just the parts of the germ that triggers the immune system;

c) just the genetic material that provides the instructions for making specific proteins and not the whole virus.

a) Whole virus

Here three approaches can be used

a.1) Inactivated vaccine

The virus is inactivated or killed by chemical, heat, or radiation. It requires special lab conditions for production and has a long production time. It likely requires more than one dose.

a.2) Live attenuated vaccine

The virus is live but disease-causing ability is weakened. It also needs a special lab and is time-consuming. This may not be suitable with compromised immune systems people.

a.3) Viral vector vaccine

A safe virus called as a vector is used along with the pathogen protein. The protein then triggers the required immune response.

b) parts of the germ

Also called as a subunit vaccine. As the name suggests, it contains a subunit or part of the organism. Most childhood vaccines are these types.

C) genetic material

The genetic material DNA or RNA is used in the vaccine. This approach is new for vaccine development. Earlier genetic material vaccines were undergoing clinical trials still, COVID-19 mRNA vaccine is the first to get EUA. The DNA or mRNA is instructed to form the proteins, which are then recognized by the immune system to generate the response. The Link for the details is here

5) PART FIVE: Access and allocation: how will there be fair and equitable allocation of limited supplies?

Once a vaccine is allowed for use, its equal and fair distribution is essential. WHO has formed COVAX (The COVID-19 Vaccines Global Access) Facility. It is formed to bring together nations regardless of economic status to have an equal distribution of vaccines. The vaccine allocation will be done in Phase I and Phase II. Also, humanitarian buffer will be kept for use whenever required. The Link for the details is here

6) PART SIX: Country readiness for COVID-19 vaccines

Every nation should have its distribution plan for vaccine ready, in order to avoid any hassle during vaccination. National Deployment and Vaccination Plans (NDVPs) are reviewed by WHO so that 92 low and middle-income countries under COVAX gets vaccination program done effectively. The Link for the details is here

 Pharmaceutical Microbiology Resources (


  1. Nice information in simple words

  2. Informative and quite easy to understand all the procedure that is taking place.

  3. That was informative and understandable, Hoping to see more such articles.


Pharmaceutical Microbiology Resources

Special offers