The approval of the AstraZeneca vaccine is welcome news indeed. Welcome for Australia and our region.

The vaccine efficacy against symptomatic infection using any dosage interval was 63% (51%,72%). There were no hospitalisations or deaths. With increasing spacing between vaccine doses, the vaccine efficacy increased to 78%.

In the elderly vaccine efficacy maybe less; but <10% of participants enrolled were >65 years so the data is not yet strong. US clinical trial data will have more data in the elderly in the coming months.

As with any immunisation program, the vaccine effectiveness (real world) data is awaited. Data from the UK should be available later this month using a schedule spaced 12 weeks apart in the elderly and healthcare workers. Additionally vaccine impact data will also be forthcoming over the year. The real impact of a vaccine will only be seen once it is used in a population and most importantly will it stop transmission? This is critical and there are good reasons to believe that this will occur.

Our Pacific neighbours often look to both WHO and Australia for guidance on vaccines. WHO’s interim guidelines recommend the use of the vaccine in people >18 years. They recommended that two doses to be administered 8-12 weeks apart as it improves efficacy.

As with any immunisation program, it is likely that modifications to the program will be made as further information comes to hand. Although vaccine efficacy was preserved with the B.1.1.7 variant, it is likely that a booster dose, with perhaps the Sputnik vaccine (another adenoviral vector vaccine), may improve efficacy against other variants. These studies are ongoing along with a study in South Africa designed to see whether it prevents severe COVID-19 and death.

Nevertheless, in the context of a global shortage of vaccine and a global pandemic we must use the vaccines that are available now, then modify the program later.

Australia really is not high in the queue and is not a priority for vaccine. However, our Pacific neighbours are with high rates of diabetes and obesity. It is therefore vital that they are prioritised for vaccination, and start using a vaccine that is available and affordable. Having consideration for the decisions we make and a view beyond our borders is essential to ensure we are all safe in the long run. Some small Pacific island countries are about to receive enough AstraZeneca vaccine to vaccinate 30% of their population. And now with TGA and WHO they can start vaccinating as soon as it arrives and vaccinate the elderly.

It’s great that the AstraZeneca coronavirus vaccine has been approved for use in Australia. It’s proven to be safe and effective and has already been administered to several million people worldwide. The WHO has endorsed it as being a safe and effective vaccine for anyone over the age of 18. To have a vaccine that is safe, effective in reducing severe disease and is able to be made here in Australia is a wonderful outcome.

This means we are not tied to global supply chains and, since the vaccine is stored in the fridge, and not at super cold temperatures, we can roll it out to GP clinics across Australia. Most importantly, in those who have received the vaccine there have been no deaths from COVID-19. That’s 100 per cent protection so far. It has reduced hospitalisations, in fact none were reported in the trials, which will take the pressure off many hospitals overseas that are struggling with the number of COVID-19 patients they are treating.

There is early emerging data suggesting a reduction in transmission by as much as 67 per cent, which is promising, but we need to wait a little longer for that data to come through.

The way the AstraZeneca vaccine works is that it uses part of another common but harmless virus (Adenovirus vector) with a piece of COVID-19 viral DNA (cDNA) inserted into it. The Adenovirus vector and the cDNA both trigger an immune response but it is the body's response to the cDNA that really matters.

My major theoretical concern about the AstraZeneca COVID-19 vaccine is that the same Adenovirus vector is present in each dose. The immune response to the Adenovirus is very much larger, and likely to be antigenically stronger than the immune response to the COVID-19 cDNA inserts. If so, it could at least partly inhibit the secondary response by eliminating the Adenovirus before the cDNA can replicate enough to fully trigger the immune system. This possibly explains why responses to AstraZeneca appear to be lower than those induced by the Pfizer and Novavax vaccines.

A similar Russian COVID-19  Adenovirus-vectored vaccine (SPUTNIK-V) uses antigenically different Adenovirus vectors for each dose.

The TGA just approved the Astrazeneca/Oxford vaccine to immunize against COVID-19 disease. The advantages of this vaccine for Australia include its ease of production, with CSL able to produce downstream large quantities locally, as well as distribution and storage at conventional fridge temperatures. 

While initial data suggested similar efficacy to protect against disease in young and older adults,  some regulatory bodies queried if there was data from enough older individuals to support this conclusion confidently. Data is still building up on this issue in ongoing human trials globally. It is good to remember however that initial Phase I and II clinical trials which compared younger and older adults, did show similar safety profiles and similar immune responses being induced. Therefore, the emergence of differences in efficacy for these different age groups at this stage would be surprising.

Moreover, a recently released pre-print in review for The Lancet shows 76% efficacy after one jab, increasing to 82% after a booster jab given 3 months later. Excitingly, new data is also shown that the vaccine eliminates the virus itself (on top of disease symptoms), opening the possibility that vaccination could both prevent disease and become be a transmission breaking tool.

The ‘full conditional approval’ of the AstraZeneca vaccine today great news for the delivery of our vaccine roll-out program in Australia.

The important take-home message is that the vaccine is safe. It has undergone a very thorough assessment process to get this approval, and further, not only have clinical trials been conducted but it has been administered to many millions worldwide. All of this should give us great confidence in receiving this vaccine.

We also know that the vaccine is effective against preventing severe illness and hospitalisations and so will be a very important part of protecting the Australian population in this next phase of the pandemic.

The vaccine is approved for use in those over 18 years of age. Although no upper age limit for the use of the vaccine, it has been decided that immunising the elderly should occur on a case by case basis.

The advantages of this vaccine are the local production capability and storage at normal room temperatures.

Whilst there is ongoing concern about what effect the new variants will have on all of the vaccines that have been made based on the original Wuhan variant of the virus, CSL, the manufacturer of the vaccine in Australia, has indicated that it is confident that it will be able to update the vaccine if required.

It is extremely good news that the TGA has approved the AstraZeneca vaccine for use in Australia. It is imperative that the population is vaccinated as quickly as possible, and having multiple vaccines available secures supply. The AstraZeneca vaccine is a good vaccine, and the data that is arising from other nations suggest that the efficacy is higher than the original publications.

Finally, all vaccines have clearly demonstrated that they are safe, and importantly there are no deaths or severe cases of COVID requiring hospitalisation in those who have been vaccinated. This is an incredibility important outcome in managing our healthcare resources.

It is great news that the Therapeutic Goods Administration (TGA) has finally approved supply of the Oxford-AstraZeneca vaccine in Australia.

Questions have been raised about the efficacy of this vaccine and its use in certain age groups and population cohorts. 

A cautious approach is still required but this should not represent a significant barrier to immunisation with this vaccine. 

Public confidence should be high for a vaccine that does not require very cold temperatures for storage, no serious adverse effects, and manufactured in Australia under strict regulation guidelines provided by the TGA.