Some questions on the AztraZeneca COVID-19 vaccine answered.

There appears to be 4 segments in the PNG population regarding COVID-19 vaccination. First group are the anti-vaccine group. This group does not want to have the COVID-19 vaccine and are strongly advocating against it. Second group are those that clearly want the vaccine and want to have it as soon as possible. Third group are those that are just not sure yet so playing it safe. They prefer to wait and see. The fourth group has no clue about the vaccine and do not know what to do. Or are waiting to be told what to do, perhaps by those that are vocal the most and their voice loudest in main stream media or social media.

So I decided to do a bit of research on the AztraZeneca vaccine, which is being given in PNG.

The AstraZeneca vaccine’s full name is Oxford-AztraZeneca COVID-19 vaccine. Code name AZD 1222. It was jointly developed by Oxford University and AstraZeneca, a British-Swedish pharmaceutical company.

What is in the AztraZeneca COVID-19 vaccine?

AztraZeneca vaccine contains a chimpanzee adenovirus that has been made harmless. This process of using harmless viruses in vaccines is referred to as a virus vector. This is a common practice for making vaccines and this technology has been used since the 1970s. Viral vector technology has been used in outbreaks caused by Ebola, Zika and respiratory syncytial virus. Trials for HIV and malaria vaccines have used viral vectors as well. The harmless adenovirus in the AztraZeneca vaccine contains the genetic code for the COVID-19 spike protein. This molecule on the COVID-19 virus allows the virus to enter human cells to cause disease.

How does AztraZeneca vaccine work?

The vaccine is given as an injection into the muscle. It is a 2 dose vaccine. The second dose can be given after 8 to 12 weeks. I will give a simple explanation in 4 steps.

Step 1. The vaccine is injected into the muscle.

Step 2. The harmless virus (viral vector) is ingested by immune cells and destroy the harmless virus in the vaccine. Then the immune cells produce the spike protein and display the spike protein on their surface so that it acts as signal for other immune cells to recognise it. In a way the surface spike protein marks that cell for destruction by other immune cells.

Step 3. The immune cells that display the spike protein are destroyed by the body’s immune system. In the process the body creates antibodies (which recognise the spike protein). The immune system also creates memory immune cells that remain in the body for life.

Step 4. If the vaccinated person encounters the COVID-19 virus, the body’s immune system recognises the virus very quickly and triggers and immune response because of the circulating antibodies and memory immune cells.

How effective is the AztraZeneca vaccine?

AztraZeneca vaccine trials showed an effectiveness of about 62% in preventing symptomatic COVID-19 disease 2 weeks after the second dose. The vaccine is 76% effective in preventing symptomatic COVID-19 disease after the 1st dose.

What are the common side effects of the AztraZeneca vaccine?

Common side effects include:

  • tenderness, swelling and/or redness at the injection site
  • headache
  • muscle ache
  • feeling tired
  • fever (temperature above 37.8°C).

Uncommon side effects include:

  • feeling dizzy
  • decreased appetite
  • abdominal pain
  • enlarged lymph nodes
  • excessive sweating, itchy skin or rash
  • Pins and needles
  • Sudden shivering
  • Migraine headaches
  • Feeling like vomiting

What are the serious side effects?

A rare but common side effect to all vaccines is anaphylactic reactions (severe allergy). There have been reports of people (37 people) who had blood clots after AztraZeneca vaccine which led to some European countries stop giving the AztraZeneca vaccine. But after extensive review and analysis, it has been found that AztraZeneca vaccine is not linked to blood clot formation. This was an in-depth review that included reviewing clinical trial data, vaccine manufacturing data and autopsy examinations.

I hope this information will help inform the segments of the PNG’s population who are unsure about the AztraZeneca COVID-19 vaccine. My view is that COVID-19 vaccination should be voluntary.


About rodney itaki

Medical doctor and public health specialist from Papua New Guinea.
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