Chemistry

Introduction to Vaccines

Rheem A. Totah, PhD

Associate Professor

Medicinal Chemistry, School of Pharmacy

rtotah@uw.edu

Questions we will answer today:

• What are vaccines? How are they different from

drugs? Is it necessary to vaccinate?

• What are the types of vaccines? Focus on flu

and potential COVID-19 vaccine.

• What are the components of vaccines?

• What are some of the reasons for vaccine

refusal especially for flu?

What are vaccines?

The WHO defines vaccines as:

“A biological preparation that improves immunity to a particular disease.

A vaccine typically contains an agent that resembles a disease-causing

microorganism, and is often made from weakened or killed forms of the

microbe, its toxins or one of its surface proteins. The agent stimulates

the body’s immune system to recognize the agent as foreign, destroy it,

and “remember” it, so that the immune system can more easily

recognize and destroy any of these microorganisms that it later

encounters.”

Vaccines focus on your immune system

Vaccines vs. Drugs

Vaccines are very different than drugs:

• It is expensive and difficult to get vaccines approved.

• Drugs go to a small number of sick people who need them.

• Vaccines are administered to millions of healthy people to help them not get sick.

• With diseases becoming rare, the focus is more on the vaccine than the disease

• Public confidence in vaccine safety is more critical than drugs

– higher standard of safety is expected of vaccines

Why Do We Vaccinate?

Some diseases do not have drug treatments, or any other treatment, and have

been well controlled with vaccinations.

The Concept of Herd Immunity

• Live attenuated vaccine.

• Killed vaccines or segmented vaccines

• Polysaccharide and conjugated vaccines

• Virus Like Particle Vaccines

• DNA and RNA vaccines

Types of Vaccines

• 100% effective

• Oral dosage form

• No adverse effects

• Highly immunogenic

life-long immunity from a single dose

no boosters required

• Cheap

• Stable at room temperature

The Perfect Vaccine

What is in a vaccine?

Vaccines have :

– Antigenic material, weakened/killed virus or bacteria

-Stabilizers (mono sodium glutamate, 2-phenoxy

ethanol)

– Adjuvants (increase immune response)

– Preservatives (prevent fungal and bacterial growth)

(e.g antibiotics, formaldehyde and in

some cases thimerosal)

Are Vaccines Safe?

No vaccine is 100 percent safe. Almost all vaccines can

cause pain, redness or tenderness at the site of injection.

Some vaccines cause more severe side effects.

However, the danger (the disease) must be significantly

greater than the means of protecting against the danger

(the vaccine). In other words, a vaccine’s benefits must

clearly and definitively outweigh its risks.

Established in 1990, the Vaccine Adverse Event Reporting

System (VAERS) is a reporting system to CDC that

records adverse events reported in the US.

Flu Season and Flu Vaccine

• Highly infectious viral illness

• First pandemic in 1580

• At least 4 pandemics in 19th century

• Estimated 21 million deaths worldwide in

pandemic of 1918-1919

• Virus first isolated in 1933

Influenza Complications

• Pneumonia

– secondary bacterial

– primary influenza viral

• Reye syndrome

• Myocarditis

• Death 0.5-1 per 1,000 cases

How is the flu vaccine prepared?

March 2019

It is recommended that quadrivalent vaccines for use in the 2019-

2020 northern hemisphere influenza season contain the following:

an A/Guangdong-Maonan/SWL1536/2019 (H1N1) pdm09-like virus;

an A/HongKong/2671/2019 (H3N2)-like virus;

a B/Washington/02/2019- like virus (B/Victoria lineage);

a B/Phuket/3073/2013-like virus (B/Yamagata lineage).

Vaccine effectiveness

Flu Vaccine Myths or Facts

• The Flu is not serious it is just like a bad cold.

• Only at risk among the population should get the flu vaccine (>65, pregnant,

immune compromised)

• It is better to get the flu than to get the flu vaccine.

• You can get the flu from the vaccine.

• It is better to get the vaccine early in the season to be protected throughout

the season.

• You can skip years when getting the flu vaccine.

Reasons for Vaccine Refusal

Religious Reasons

Personal Beliefs or Philosophical

Reasons

Safety Concerns, some still

believe

the study published in the 1980s

Desire for Additional Education

Vaccines and other treatments for COVID-19

Work is progressing quickly to find a treatment and a vaccine for

SARS-CoV-2.

In terms of vaccines, clinical trials in Seattle is underway to test the

safety of an RNA vaccine against SARS-CoV-2. Many other vaccine

trials around the world working on DNA vaccines or isolating viral

proteins that can serve as antigens.

Monoclonal antibodies are usually isolated from patients who have

recovered from COVID-19 and administered to patients fighting the

disease. The idea is that it will boost your body’s immune response

to help fight the virus and prevent serious complications.

Remdesivir (GS-5734)

Remdesivir is an adenosine analog prodrug developed by Gilead Sciences. It inhibits viral RNA dependent RNA polymerase and results in chain termination. It is active against several RNA viruses and showed promise against SARS and MERS.

It has received approval and was used to treat a patient in Snohomish county. The drug improved the clinical condition of the first patient infected by SARS-CoV-2 in the US, and a phase III clinical trial of remdesivir against SARS-CoV-2 was launched in Wuhan on February 4, 2020. So far the data is promising.

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