Three that have recently released Stage 3 results and are awaiting approval are the mRNA based Moderna and Pfizer vaccines, and the viral vector based Oxford University/AstraZenica vaccine.
The Moderna and Pfizer vaccines require 2 full strength doses over about 28 days, while the Oxford/AstraZenica uses a half strength dose followed by a second full strength dose.
There are some key differences between the UK’s Oxford version and the US-based Moderna and Pfizer versions.
The Oxford vaccine, called ChAdOx1 nCoV-19, is made from a weakened version of a common cold virus (adenovirus), that has been genetically changed so that it cannot grow in humans.
Adenovirus vaccines have been researched and used extensively for decades, with the benefit that they are stable, easily made and can be stored at the same temperature as a domestic fridge.
This means they could be easily distributed and deployed using the existing supply chain based on using GP surgeries and pharmacies. It also means it could be easier to administer in hotter climates or developing countries where such facilities for cold storage do not exist.
Even if the AstraZeneca-Oxford vaccine proves to be less effective than those by Pfizer or Moderna it has a number of other aces up its sleeves.
Firstly, an effectiveness of 70 per cent is still considered to be good considering the annual flu vaccine is generally only 40 – 60 per cent effective.
The Oxford dose may also provide a level of protection from people transmitting COVID-19, something that has yet to be ascertained in the rival vaccines.
It also is thought to travel better and can be stored is standard fridges unlike the Pfizer vaccine which needs to be kept at -70C.
Additionally, the Oxford vaccine already has a production line ready to start cranking up with AstraZeneca estimating it could have 200 million doses ready in just weeks. In Australia, local biotechnology company CSL has been pumping out the vaccine since early November.
It will cost between USD$5 and $6 for the two doses, whereas the Modena and Pfizer vaccines will cost between USD$30 and $40 for the two doses.
The Moderna and Pfizer versions by contrast, rely on mRNA technology and are created in a lab using chemicals, enzymes, bacteria or live cells.
Scientists essentially make a synthetic version of the virus’s messenger ribonucleic acid (mRNA). This then prompts the body to make a particular protein, which is detected by the immune system and this causes the immune system to make antibodies to fight against it.
Pfizer’s drug needs to be stored at -94F (-70C), and public health resources are stretched thin after nearly a year of pandemic response. If the Pfizer vaccine it approved, it is a novel vaccine which requires ultra-cold storage. Each suitcase-sized shipping container will have 975 doses in five-dose vials. The vaccines are viable for 10 days from the moment the case is sealed, and packed with dry ice to keep them cold. The cases can only be opened a maximum of twice a day, for one minute at a time, according to Soumi Saha, an attorney, pharmacist and vice-president of advocacy at the healthcare logistics company Premier Inc. “The clock starts well before you actually receive the product.” The vaccine still must be transported on dry ice from any location away from an ultra cold deep freezer, and properly diluted before people receive a shot in the arm. Vials last for five days after they are thawed, and for only six hours after they are diluted.
It may be a Betamax vs VHS situation, where one may be technically more advanced and more effective, but very expensive and logistically difficult. The other is inexpensive, easy to produce and distribute, and statistically almost as effective. Perhaps countries will invest in the more expensive one for urban areas, and the less expensive one in other areas lacking in the required infrastructure.
I am still hoping something will happen with University of Queensland protein sub-unit vaccine which is still in Stage 1 trials, or the University of Melbourne and Murdoch Children’s Research Institute; Radboud University Medical Center; Faustman Lab at Massachusetts General Hospital live-attenuated vaccine which is in Stage2/3 trials at the moment.
As for Australia, we are still sitting at 907 fatalities from Covid-19 from a population of 25 million. The outbreak that hit Melbourne is over, a month since any new cases, and down here in Tasmania it’s been 105 days since any cases at all. The country is pretty much opened up, and any overseas arrivals still have to be quarantined unless coming direct from New Zealand. Once a virus candidate is approved here, it will be free of charge, and given first to front line health care workers and people in nursing homes, then to other more susceptible groups such as Aboriginals, the over 65’s, and other vulnerable groups.