mRNA COVID Vaccines

Vaccinations and Herd Immunity

The different types of vaccines

• Subunit vaccines, containing a fragment of the pathogen

• Live attenuated vaccines, containing a weakened form of the pathogen

• Inactivated vaccines, containing a dead version of the pathogen

• mRNA vaccines, containing mRNA from the pathogen that teach our cells to produce proteins from the pathogen to trigger an immune response

• Viral vector vaccines, using modified virus cells to deliver genetic information to

COVID-19 Vaccines

What are each of them made of?

Astra-Zeneca vaccine

• This is a viral vector vaccine

• Uses a modified version of an adenovirus, which are common viruses usually causing colds or flu-like symptoms. The chosen adenovirus can enter human cells, but can't replicate inside them

• The virus has been modified to contain COVID-19 DNA, containing the gene to produce spike proteins from the COVID-19 virus

• APCs can present the spike proteins to helper T cells to produce an immune response

The Pfizer Vaccine

• This is an mRNA vaccine

• When the mRNA enters the cells, the instructions tell the cell to produce the spike protein

• Immune cells can then recognise the protein as foreign to produce an immune response

• These vaccines do not contain any live virus, and don't interrupt our DNA sequence at all. AstraZeneca used the vector version as DNA is a more stable molecule than RNA.

Multiple Choice

Which type of vaccine uses a weakened version of the pathogen?

• Subunit

• Live attenuated

• Inactive

• mRNA

• Viral vector

Multiple Choice

What type of immunity is gained from a vaccination?

• Natural passive

• Natural active

• Artificial passive

• Artificial active

Multiple Choice

What kind of vaccine uses a modified virus cell to deliver genetic material to the vaccinated?

• Subunit

• Live attenuated

• Inactive

• mRNA

• Viral vector

Vaccine Efficacy

The important value that measures the effectiveness of the vaccine

What is vaccine efficacy?

• Vaccine efficacy is a measurement, expressed as a percentage, that represents the reduction in infection between a control group receiving a placebo, and the experimental group receiving the vaccine.

• An efficacy rate of 90% could mean that if a control group of 100 people were all infected, the experimental group of 100 people would have only 10 people infected by the virus. The vaccine reduced infection rate by 90%.

COVID-19 Efficacy Rates

The Pfizer vaccine has an efficacy rate of 95%.

The AstraZeneca vaccine has an efficacy rate of 76%, but 100% for severe disease caused by the virus.

Open Ended

Describe what efficacy rate means in regards to vaccines.

Herd Immunity

Reducing the spread of infection

What is herd immunity?

• The goal of a vaccination program is to produce herd immunity in the population

• When enough people have been successfully vaccinated, this reduces the spread of infection, even to unvaccinated people, since vaccinated individuals will not spread the pathogen as easily

Why is herd immunity important?

• The more vaccinated people there are, the less people there are as potential carriers of the pathogen

• Some people cannot be vaccinated (people with immune diseases, taking medication that suppresses immune system, the elderly and newborn babies) so these people rely on herd immunity to prevent the spread of the virus to them.

Case study - whooping cough

• If you've known someone with a newborn, they may have asked you to get a whooping cough vaccine before meeting the baby.

• Some immune memories don't last forever - this is true for whooping cough. You need a booster every 10 years to maintain immunity to whooping cough.

• Herd immunity can be lost if people don't maintain their schedule of booster shots - this is concerning as some diseases are able to be 'eliminated', but only if people keep getting vaccinated.

Multiple Choice

What is the efficacy rate of the Pfizer vaccine?

• 90%

• 95%

• 76%

• 100%

Multiple Choice

What is the efficacy rate of the AstraZeneca vaccine against serious disease?

• 90%

• 95%

• 76%

• 100%

Open Ended

Explain why herd immunity is important for the population as a whole.