Moderna Inc. may have an easier time with distribution than Pfizer Inc. since its COVID-19 vaccine candidate can be stored at much lower temperatures.
Moderna announced that its mRNA-1273 formulation – which is 94.5% effective – remains stable at 2° to 8°C, the temperature of a standard home or medical refrigerator, for 30 days, as opposed to an earlier estimate of seven days.
mRNA-1273 remains stable at -20° C for up to six months, at refrigerated conditions for up to 30 days and at room temperature for up to 12 hours.
The biotech said that using standard freezing temperatures is a more established method of distribution and storage than deep freezing, while most worldwide pharmaceutical distribution companies have the capability to adapt to it.
Conversely, many experts have already highlighted that the requirements of Pfizer’s formulation – which is 90% effective – may be a significant hurdle in rolling it out.
Not only it must be stored at ultra-cold storage, between -60°C and -80°C, but it is also administered in two doses 21 days apart, while other competitors only have a single dose.
“Whereas this is a challenge in developed countries, some have argued that it could be almost impossible in some parts of the developing world,” Adam Barker, analyst at Shore Capital, commented.
“In response, Pfizer is establishing its own supply chain and plans to distribute the product direct to vaccination sites (avoiding wholesalers) in specially designed cooler boxes.”
These allow the vaccine to be maintained for ten days, and once removed from its container, it can survive for around a day at temperatures of 2-8°C.
However, the product is so sensitive to temperature that there are recommendations on how often the box should be opened and it survives for just two hours at room temperature.
“Suffice to say, most facilities (e.g. GP surgeries, pharmacies) don’t have the freezers required to store the vaccine at such low temperatures and shipping in large quantities of dry ice to keep re-icing the containers isn’t necessarily simple either,” Barker added.
“Even though the establishment of the supply chain necessary to distribute Pfizer/BioNTech’s vaccine clearly isn’t impossible to achieve, it is going to be challenging and will require a great deal of coordination at vaccination sites.”
Last week, Reuters reported that US states, cities, and hospitals are racing to buy ultra-cold freezers for Pfizer’s jab even if the US Centres for Disease Control and Prevention have advised not to do so.
Both Moderna's and Pfizer's vaccines are mRNA-based, meaning they instruct a patient’s own cells to produce proteins that could prevent, treat or cure disease.
Driving the process is messenger RNA, or mRNA, which plays a fundamental role in human biology by transferring the instructions stored in DNA to make the proteins required in every living cell.
Traditionally, vaccines are made of an inactivated virus; recombinant proteins that stimulate an immune response.
By providing the body’s defence mechanisms with advanced warning of the virus, they trigger production of the antibodies required to fight the real thing when it is contracted.