Is there really a difference between the Covid-19 vaccines?

corona virus vaccines

As you’re probably aware, the Therapeutic Goods Administration (TGA) has approved two covid-19 vaccines for use in Australia from Pfizer and AstraZeneca. The Federal Government has also determined who will receive which vaccine and when:

Quarantine and border workers, frontline healthcare workers, aged care and disability staff, and aged care and disability residents will mostly, but not exclusively, receive the Pfizer vaccine.

Pretty much everyone else at this stage will be getting the AstraZeneca vaccine. 

Is there really a difference between the Covid-19 vaccines?

It depends on what the goal is.  2021 is the year of turning COVID-19 into the common cold – in other words, not fatal or requiring hospitalisation.  Both vaccines achieve that with well over 90% effectiveness.  Where they may differ is in their rates of reduction of transmission of the virus and how well they resist new variants such as the one from South Africa. Both vaccines deliver a genetic message to cells to produce the spike protein of the coronavirus, which then trains our immune systems against future infections.


Pfizer’s vaccine uses a new technology involving messenger RNA (mRNA). The clinical trials showed that the vaccine is 95% effective in preventing all symptoms – not just the severe ones. Two doses are required at least 21 days apart. The vaccine is manufactured overseas, and Australia has secured 20 million doses which will be delivered throughout the year.  The vaccine must be mostly stored at -70 Degrees Celsius. 


The AstraZeneca vaccine is called a viral vector vaccine which uses a modified version of a chimpanzee virus (the vector) to deliver the genetic instructions to our cells. When the doses are given 12 weeks apart, the efficacy is around 82%. Australia has secured over 50 million doses, most of which will be produced in Melbourne by biotechnology company CSL. It must be stored at 4 Degrees Celsius.

Results from Scotland, England and Israel, show the real world effectiveness of both vaccines.

Before any vaccine is approved for use in Australia, it must pass the TGAs rigorous assessment and approval processes. The TGA is closely monitoring the rollout both here and overseas.

It is also important to note that both vaccines have already been administered to tens of millions of people around the world, and we are seeing COVID-19 rates decline in many countries.

Given the geographical nature of Australia, it is easier to administer the AstraZeneca vaccine to the entire population as it can be stored in normal refrigerators at medical centres and pharmacies.

Australia has also guaranteed supply of the AstraZeneca vaccine by entering into an arrangement to manufacture it onshore. Australia has secured only 20 million doses of the Pfizer vaccine and is reliant on overseas supply chains.

The story with variants is evolving.  It may be that Pfizer is more effective, but the important thing at the moment is to get immunised, so you’re safe from disease when the borders open up – as they have to do sometime.

Should you wait to receive the Covid-19 vaccine even if you have been offered it now?

There’s no reason to wait.  The sooner you have the first dose, the sooner you get the second and receive full coverage against severe COVID-19. If you’re worried about whether you or a family member should get the vaccine, please talk to your doctor.


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