you and your health

The path to vaccination

Understanding how vaccines are developed, produced and licensed

By JAMES D. LOMAX
Posted 9/30/20

We are all aware of how the COVID-19 virus has spread worldwide and that each day the world discovers how persistent this pandemic has become. We are averaging at least 40,000+ newly reported cases …

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you and your health

The path to vaccination

Understanding how vaccines are developed, produced and licensed

Posted

We are all aware of how the COVID-19 virus has spread worldwide and that each day the world discovers how persistent this pandemic has become. We are averaging at least 40,000+ newly reported cases and at least 1,000 deaths each day in the United States.

There is a huge effort worldwide to develop vaccines to protect vulnerable people from coronavirus. The term “herd immunity” is often used as a goal from vaccinations. At least 70 to 80 percent of a population needs to carry protective antibodies against COVID-19 to slow and stop the spread of this infection.

This article discusses of how vaccines are made. After a potential vaccine is produced by a drug company, there is a multistep process that is followed that evaluates safety and potential effectiveness.

How do vaccines protect us?

Vaccines contain non-disease proteins that stimulate our immunity cells to create a “memory” of exposures to specific disease-causing bacteria and viruses. These memory cells (B and T cells) recognize the pathogen and create antibodies that will neutralize the bacteria or virus. All vaccines are created by using a modified pathogen that is weakened to allow your body to develop an immune response without you becoming ill.

The main types of vaccines include live, attenuated, inactivated, subunit, conjugate and toxoid. Refer to  “Types of vaccines” below for a brief description of each.

New types of vaccines that are currently being developed to defend against COVID-19 use various modified viruses to introduce DNA or messenger RNA instructions into immune cells to produce specific antibodies. Researchers are transplanting SARS-CoV2 into cold and other zoological viruses. These modified viruses in turn inject the SARS-CoV2 into immunity cells that then develop an immune response. The carrier virus and the SARS-CoV2 virus does not cause illness. This technique worked well in developing a vaccine for Ebola. Currently, there are about 100 pharmaceutical and research facilities worldwide that are producing prototype vaccines for testing using various techniques.

Types of vaccines:

Live, attenuated vaccines use a live virus that is modified to the point of not causing disease. Examples include Varicella (chickenpox), MMR (measles, mumps and rubella) and the nasal form of influenza “flu” vaccine.

Inactivated vaccines contain a virus that has been killed and completely incapable of causing disease. Examples include the influenza flu vaccine, polio, hepatitis A and rabies.

Subunit vaccines contain purified pieces of the virus to create the vaccine. Examples include Hepatitis B (HBV) and human papillomavirus (HPV).

Conjugate vaccines combine the outer sugar-like coatings found on some bacteria to protein that then induces an immune response. Examples include Haemophilus influenza type b bacterium (HIB) that protects against meningitis.

Toxoid vaccines contain inactivated toxins that are no longer capable of causing harm or disease. Examples include DTap and Tdap vaccines for protection against diptheria, tetanus and pertussus/whooping cough.

How potential vaccines are tested

There is a routine way that vaccines are developed and tested for safety and
effectiveness. Below are the steps that are usually followed:

The exploratory stage involves basic lab research and generally takes two to four years of work for the lab to identify natural or produce synthetic proteins (antigens) for study.

In preclinical studies, tissue or cell cultures are used to develop enough protein to test on animals (often mice and monkeys). The protein is introduced into the animal’s immune system to produce antibodies along with observing the animal for symptoms and blood responses. Most vaccine candidates do not make it past this point.

The vaccines that do make it submit Investigational New Drug (IND) applications to the FDA. Generally, these take about 30 days for review and are required to proceed to human studies.

During Phase I vaccine trials, a small group of adults (between ages 20 and 80) are injected and observed for safety and whether there is an antibody response. If this vaccine is for children, adults are used first. There is also, in some studies, a challenge test to attempt to infect the person after the initial vaccine is injected.

If there are promising results from the Phase I group, the next step is to expand it to several hundred volunteers in Phase II. Included in the study group are people who are at high risk for infection, along with study individuals who received placebos and people receiving various strengths of vaccines.

Once at the Phase III point of trials, at this level of development, thousands to tens of thousands are studied. The design of the study also includes injecting placebos for double-blind studies. The questions that are asked are whether this vaccine prevents disease, and are the antibodies produced sustaining and give long-term protection.

If the vaccine is promising, the FDA will carefully review the results, inspect the production facilities and, in some situations, do their own testing before releasing it for general use.

COVID-19 vaccine development

Because of the rapid spread of this virus across all countries of the world, there has been a push to shorten or condense the study periods for various vaccines being produced. Some of the reduction of development time is possible because the proteins being produced by some companies had been used in other studies in relationship to other diseases. Several international companies are using the SARS-Cov-2 virus. It is important to know that it generally takes many months to years to develop a successful vaccine. To date, there are no vaccines that are close to licensing and dispensing worldwide.

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