A vial of the COVID-19 vaccine is prepared to be administered at Walter Reed National Military Medical Center, Bethesda, Md., Dec. 21, 2020. (DOD Photo by Navy Petty Officer 1st Class Carlos M. Vazquez II)
  • New data  confirms the lifespan of a Pfizer COVID vaccine in a bar fridge is 31 days, not 5 as originally estimated.
  • Adopting this storage policy would result in simpler logistics for site managers, faster immunisation coverage, cheaper equipment and less waste.
  • South Africa’s regulatory body has approved the change in storage conditions and the health department sent out a circular on 21 May informing vaccination sites that unopened, thawed Pfizer vials can be now stored in a fridge for up to 31 days.

South Africa’s medicines regulatory body, the South African Health Products Regulatory Authority (Sahpra), has approved changes to the storage conditions for the Pfizer COVID vaccine, allowing it to now be stored in a refrigerator for a month. This extends the shelf life of the doses six-fold — from five to 31 days — and will help to speed up the country’s vaccine roll-out because the new storage conditions will result in simpler logistics, cheaper equipment and less waste.

In a circular issued on 21 May, the health department instructed vaccination sites to follow the new guidance with immediate effect — also with regards to batches that have already been distributed. 

The updated storage conditions follow similar approvals last week by the European and American regulatory bodies — the European Medicines Authority (EMA) and the Food and Drug Administration (FDA) — based on new data provided by Pfizer.

South Africa has received four batches of Pfizer vaccines so far, which brings the total number of doses to about 1.3-million (each person requires two shots), according to the health department’s delivery schedule. The country will get an additional 636 480 doses each Sunday night in June, Health Minister Zweli Mkhize said on 16 May. 

The roll-out will eventually also include the Johnson & Johnson (J&J) jab, once a verification process by international regulators has been concluded, that will allow the Aspen pharmaceutical company’s Gqeberha plant to release South Africa’s first installment of 1.1-million doses.

What do these changes mean for South Africa’s roll-out?

Phase one B and phase two of South Africa’s COVID vaccine roll-out, which started on 17 May, use the Pfizer jab.

Pfizer’s vaccine initially presented one of the biggest cold-chain challenges of all the potential COVID jabs, as it required ultracold storage. The vaccine vials arrive in specialised thermal shipping containers which use dry ice to keep the doses frozen between -80 to -60°C. The jabs can be kept at this temperature until their expiry date, which is estimated to be about six months. But keeping the jabs at well below freezing requires expensive, special freezers.

An alternative, which South Africa has chosen to adopt in its own roll-out, is to keep the vials in a normal freezer between -25 to -15°C for up to two weeks. Pharmacists and site managers at vaccination sites then estimate how many jabs a site will need for a particular week, thaw that number of frozen shots and keep them in fridges (once thawed, the jabs cannot be refrozen). 

Up until now, the thawed jabs could be kept in refrigerators for up to five days only. But with the new storage guidelines that period has been extended to 31 days. 

The new storage conditions could help the country administer vaccines faster, save costs and avoid vaccines going to waste.

Why will the storage changes result in faster vaccinations and lower costs?   

The new policy takes a lot of pressure off South Africa’s immunisation drive by simplifying the day-to-day logistics at the country’s vaccination sites, says Nicholas Crisp, who heads up  phase one B and phase two of the roll-out for the health department. 

For starters, vaccination sites will be able to keep more Pfizer jabs on-site at a time, and in fridge storage facilities that are cheaper and easier to come by, he says.

This will decrease the burden on site managers, who would now no longer need to coordinate frequent orders of smaller batches. 

Crisp says most site administrators in the public sector aren’t yet in control of the management  of supplies at their sites, but as the roll-out continues they will have implemented systems to place orders for vaccines and other equipment such as needles to match the number of appointments they have scheduled for each day. 

Some sites in Limpopo, Eastern Cape and Western Cape are already doing their own monitoring and most private sector sites are also running their own scheduling, he says.

[WATCH] COVID vaccines – Pfizer fast facts

Crisp cautions, however, that though the new policy is being implemented with immediate effect, changes to the logistics usually take a while to kick-in, so people shouldn’t expect the benefits of the new storage requirements to be evident straight away. 

Nonetheless, the more vaccines that are available at a site, the faster people can be immunised, explains Tanuja Gengiah, head of pharmacy at the Centre for the Aids Programme of Research in South Africa (Caprisa). “This [the new storage policy] will really make [the Pfizer jab] a lot more accessible and user-friendly for people on the ground.”

The new guidelines will also help to avoid unnecessary waste, because the jabs will no longer have to be disposed of if they’re not used within the planned five-day day time slot, Gengiah says. 

But it’s important to point out that the new policy only applies to the short-term storage of unopened, thawed vials. To store the frozen vials for more than a month, the jabs will still need to be kept in special freezers at -80 to -60°C.

Do the new Pfizer storage requirements mean this jab can now also be used in rural areas? 

Because facilities in rural areas have less access to the special freezers required to store the frozen jabs at  temperatures below freezing point, the health department decided to use Pfizer jabs at mostly urban sites. (J&J jabs, that can be kept in a fridge for up to three months, will be used at rural sites).  

Crisp says because the jab’s long-term cold storage requirements are still often out of reach for facilities in rural areas, and Pfizer vaccines have to be transported in frozen conditions, the new guidelines don’t automatically mean that they can now also be used in rural areas.  

He says because mRNA vaccines have to be transported at such low temperatures and are sensitive to temperature changes, transporting the jabs for long distances on rural roads that are often not well maintained, is a risk the health department would rather not take. “Take the Eastern Cape for example,” Crisp explains, “you wouldn’t want to go up and down those paths with a vaccine that’s so vulnerable in terms of temperature.”

Why do Pfizer jabs need to be stored at low temperatures? 

The Pfizer vaccine uses a new type of technology, called mRNA, to deliver a genetic code that instructs your body to produce proteins that mirror those on SARS-CoV-2, the virus that causes COVID-19. This allows your body to mount an immune response to target these proteins, which will continue to provide you with protection if you get exposed to the real virus later on.

One of the downsides of using this form of genetic material is that your body’s cells don’t necessarily like it — so the genetic material needs a special type of carrier which will allow the mRNA to get into your body’s cells. In the case of Pfizer’s COVID vaccine, something called a lipid nanoparticle is used. This serves as an oil- or fat-based shell that encases and protects the mRNA, which can quickly degrade if exposed to warm temperatures.

So when a vial with the vaccine arrives, it contains these microscopic particles, which are too small to be seen by the human eye. These particles are then thawed and diluted using saline (or saltwater), which has to be measured carefully in order to get six doses out of a vial. A pack, or box, of Pfizer vaccines contains 195 vials — all of which need to be prepared and diluted at the vaccination sites before they can be administered.

Once the vaccine has been prepared, it also helps the mRNA become more stable, explains Caprisa’s Gengiah. This allows the doses to be kept at room temperature for longer than before the solution has been added to the vial. 

The new temperature guidelines only apply to the vials before they have been diluted, so the updated policy doesn’t influence how long prepared doses can be kept in a fridge or at room temperature. After dilution, the vaccine can be stored between 2°C to 25°C for up to six hours.

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Aisha Abdool Karim is a senior health reporter at Bhekisisa.

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Joan van Dyk is a senior health journalist at Bhekisisa.