COVID-19 Vaccine: What do we know?

Posted in COVID-19 Updates and Latest News on

Many of you would have heard that two major pharmaceutical companies, Pfizer and Moderna, have announced that their COVID-19 vaccines are nearly ready for distribution.

This is great news for everyone!

However, there is some confusion around this latest announcement – this is largely relating to the wording used by major media outlets. Pfizer announced that their COVID-19 vaccine has “an efficacy rate above 90%”, and Moderna has announced that their COVID-19 vaccine has an efficacy rate of 94.5%. The confusion is because some news outlets have been reporting that these vaccines are “effective”.

The difference between these two words is quite important. Efficacy is the performance of a treatment under ideal and controlled circumstances – basically in a laboratory setting. This means that the participants who are recruited to have the vaccine (or a placebo) are chosen very carefully and are usually quite healthy.

Effectiveness on the other hand is the performance of the vaccine under real-world conditions. The actual effectiveness of the vaccine in real-world settings will only be known after monitoring people in the real world.

Also, there have been some misunderstandings about what these vaccines actually do. Unlike more traditional vaccines, which contain a weakened version of the actual virus or parts of it, both Moderna and Pfizer’s vaccines are based on a new technology that involves taking genetic material from the virus and delivering it to healthy cells. Using molecules called messenger RNA (or mRNA), the vaccines carry instructions to the body to create the SARS-CoV-2 protein the vaccine is aiming to protect against.

The idea is that the body identifies the genetic material and new protein as a foreign body and begins an immune response. During this response, the body produces antibodies that learn to remember and fight the virus if it enters the body in the future.

While there has been confusion, the results from both the Pfizer and Moderna trials are still very promising and we can be hopeful that these vaccines will help reduce the effects of COVID-19 if you acquire it.

To give a quick summary of the findings, the Pfizer trial studied over 43,000 participants, who received either two doses of the vaccine or the placebo (not the vaccine). Within this group, 94 confirmed cases of COVID-19 were identified. Among these 94, roughly 10% had been given the vaccine, while the other 90% had not received the vaccine. This means that Pfizer’s COVID-19 vaccine has an estimated efficacy rate of approximately 90%


In the Moderna trial, 30,000 participants were studied. Researchers reported that 90 cases of COVID-19 were observed in the placebo group versus 5 cases observed in the vaccinated group. That resulted in an estimated vaccine efficacy of 94.5%.

One major difference between the two vaccines is their ability to be transported and stored. The Pfizer vaccine needs to be stored at -70C and can be stored for up to 15 days. This means that transportation of the Pfizer vaccine will require a great deal of planning and will likely be expensive.

On the other hand, it is expected that the Moderna vaccine could be stored and transported at normal fridge temperatures (around 2 to 8 degrees Celsius) for 30 days and it can be stored for up to 6 months at -20C.

The Australian Government has made agreements to buy 10 million doses of Pfizer’s vaccine, which is capable of vaccinating 5 million people; but they have not currently made any agreements to buy any doses of Moderna’s vaccine.

However, the Australian Government has secured access to another vaccine currently being developed by the University of Oxford and AstraZeneca. If this vaccine trial is also successful, Australia will have access to nearly 34 million of those doses capable of vaccinating 16.9 million people.

The success of both of these vaccines is welcome news for the entire world. However, despite these promising results, we should all continue to physically distance and practice increased hygiene behaviours. Remember to wear a mask in places where you can’t physically distance and wash your hands regularly.

Stay tuned for more information! We will be providing regular updates when more information becomes available.