- The first results for a Covid vaccine are out, with Pfizer and BioNTech reporting 90% efficacy and Moderna reporting almost 95% efficacy based on early data
- Despite its promise, cold chain requirements mean this jab wouldn’t be the first choice for countries like South Africa
- The vaccine needs to be kept at minus 70 degrees Celsius, well below other vaccines used in South Africa, which poses a huge challenge to its delivery and storage
The world’s first hope for a Covid-19 vaccine - the jab developed by drug companies Pfizer and BioNTech, showing 90% efficacy in preventing Covid-19 in early results, and Moderna’s candidate showing almost 95% efficacy - is highly unlikely to become widely available in South Africa.
This is because Pfizer’s vaccine needs to be stored below freezing temperatures - at minus 70 degrees Celsius — that the country doesn’t have the capacity to do on a large scale. If the shots are kept at temperatures too high or too low, they can spoil and become less effective.
In the United States, large city hospitals are already “rushing to buy the expensive ultra-cold freezers” that cost between R150 000 and R235 000 each, to store the shots, for which Pfizer and BioNTech will apply for an emergency license from the US regulator, the Food and Drug Administration (FDA), later this month, Statnews reports.
And just three days after the announcement of the BNT162b2 vaccine’s first interim results, the European Union signed an agreement with the manufacturers to supply it with 200 million doses and an option to request an additional 100 million doses, “with deliveries anticipated to start by the end of 2020, subject to regulatory approval”.
But South Africa doesn’t have the required ultra-cold freezers to store the vaccine - except for a few at large research institutions such as the National Institute for Communicable Diseases, says director of Vaccines for Africa at the University of Cape Town, Gregory Hussey.
And, along with less well-off rural hospitals in developed countries, the country is unlikely to be able to afford to buy enough of the freezers to be able to make the vaccine available at community health centres or clinics, or pay for the cold chain systems that are necessary to maintain the vaccines.
Most vaccines that are part of South Africa’s immunisation programme have to be kept at temperatures between two and eight degrees Celsius. The country’s system - including vaccine transportation, storage, and monitoring - is therefore not suitable for vaccines that need to be kept below freezing temperatures.
And the Pfizer/BioNTech vaccine is not the only Covid-19 frontrunner that is likely to pose a problem to South Africa. The biotechnology company, Moderna’s mRNA-1273 jab, which released its first results on Monday, needs to be stored at minus 20 degrees Celsius.
Although, the pharmaceutical company released new data on Monday showing that their candidate could be stored at a standard temperature of between two and eight degrees Celsius for up to 30 days - compared to its shelf life of six months when kept frozen. Despite this revised storage temperature, the jab still needs to be shipped and transported at minus 20 degrees Celsius.
Pfizer/BioNTech and Moderna’s vaccine both use mRNA technology. Such vaccines use pieces of man-made genetic material known as messenger ribonucleic acid, or mRNA, that instructs our bodies to produce proteins, in the form of antibodies and killer cells, to fight off SARS-CoV-2, the virus that causes Covid-19.
But the snag is that these two mRNA vaccines need to be kept at extremely low temperatures, or they risk becoming damaged.
And to complicate things even further, mRNA vaccine technology is new - not a single vaccine using mRNA messengers has been licensed for human use up to date.
“I don’t know if we could really even contemplate an mRNA vaccine with our present setup,” explains Barry Schoub, chair of South Africa’s ministerial advisory committee on coronavirus vaccines. “Things may change, but with our present setup, the places where we could actually utilise it would be so limited that it would be a major challenge.”
South Africa’s challenge of keeping vaccines cool
Maintaining a cold chain - where a product must be consistently stored at a low temperature - is important to ensure that vaccines don’t degrade or lose their efficacy. A 2018 paper in the journal Vaccine, showed that although this deterioration did not pose a safety risk to people receiving the vaccine, the jabs offered less protection after being stored at the wrong temperature.
This is a major risk for rural hospitals and clinics or those facilities that lack adequate infrastructure to properly store doses when a Covid vaccine becomes available, according to Hussey, who also serves on the Covid vaccines ministerial advisory committee.
Schoub, who is also a virologist and former director of the National Institute for Communicable Diseases, agrees: “You can’t really store vaccines reliably and sustainably at minus 20 degrees Celsius anywhere outside the bigger cities. Especially if you’re looking at places with a hotter climate, like the Northern Cape or KwaZulu-Natal, even maintaining a freezer at minus 20 is going to be a question mark.”
This means that even with Moderna’s stability at lower temperatures, South Africa’s cold chain system may be unable to handle maintaining the vaccine at its required minus 20 degrees Celsius during transport. Fluctuations in the temperature along the way could cause the jab to become less effective and offer less protection to the person being vaccinated.
According to Schoub, Pfizer/BioNTech are considering freeze-dried vaccines - in the form of frozen powders to which liquid is later added - which could potentially ease cold chain requirements for the jab, because they can be stored between two and eight degrees Celsius. But the timeline for this, he says, is still unclear.
But even without taking into account the additional obstacles that will arise with maintaining a vaccine at well below 0 degrees Celsius, just regulating the temperature for our existing vaccines is already a challenge.
An assessment of vaccine management in 18 countries done by the World Health Organisation Regional Office for Africa in 2001 found that “only 47% of the indicators were satisfactorily met for buildings, cold chain equipment, and transport at the national level”.
In the Western Cape, a 2015 study published in Vaccine found that government-managed vaccine supply chains were often unable to manage the temperatures at which vaccines need to be stored, adequately.
The average temperature of health centre fridges in the study ranged from 0.9 to 9.2 degrees Celsius, meaning that the jabs could have potentially been stored at temperatures both too low or too high and been damaged.
Why does 90% efficacy matter?
Despite the delivery challenges of the Pfizer/BioNTech vaccine, its 90% potential efficacy has physicians and scientists, who mostly expected a much lower efficiency, excited.
Although it is only initial data that could still change as the trial progresses, this kind of efficacy puts the jab in the same category as the world’s most effective vaccines, such as the measles shot.
Schoub explains: “If it does turn out to be true then that is a major, giant step forward, but at this stage it’s very difficult to assess how accurate that figure is because it’s still early in the trial.”
A higher efficacy rate means that the jab is able to offer more protection to a population. This is important when it comes to the role of a vaccine in offering immunity to a community.
If only half the people receiving a vaccine are going to be protected, you need to vaccinate a much larger portion of the population in order for it to make a difference and properly contain an outbreak.
With herd immunity as the end goal - where enough of the population is protected or resistant to the virus that it stops spreading - the measles vaccine, which is 97% effective at preventing measles, is often held up as the ideal.
But until now, scientists have been skeptical that we would be able to reach the same level when it came to Covid-19.
As Schoub explains, it was speculated that a Covid vaccine would be unlikely to offer the same level of protection as the measles shot because of the differences between the two diseases. While both are spread in a similar manner, through coughs or sneezes, they fundamentally differ in how they affect a person’s body.
Measles is a systemic disease, meaning it affects the whole body, while Covid is initally a pulmonary disease that mainly targets the lungs. In that respect, Covid is more similar to influenza, which is what has been used as the sort of benchmark when it comes to vaccine efficacy, says Schoub.
The distinction in how the disease works matters, because it influences the type of immune response - with measles requiring the production of antibodies in the blood to fight off the measles virus and influenza needing a more complicated immune response through antibodies in respiratory secretions.
The type of immune response needed to fight off influenza is hard to get through vaccinations, with most flu jabs only offering around a 60% chance of protection from the infection.
Most Covid vaccine trials are therefore designed to pick up around 60% efficacy in a vaccine candidate, the director of the American government’s National Institute of Allergy and Infectious Diseases, Anthony Fauci, explained in a Medical Brief webinar in October.
But regardless of whether the Pfizer/BioNTech candidate is suitable for South Africa, the issue of delivering a vaccine is something we need to begin working on now, says Hussey.
He concludes: “There is a huge cost involved in delivering a vaccine, the World Health Organisation has estimated that cost of delivery of vaccines could be up to two or three-fold greater than the cost of the vaccines alone.
"There is also the additional operational costs of conducting immunization campaigns during the Covid-19 pandemic. We have to ensure that the facilities, the staff administering vaccines and the recipients of vaccines are kept ‘Covid safe’. That’s something we need to factor into our planning.”
And even though South Africa is only expecting to get enough Covid vaccines for around 5% of its population by next year, and a large rollout to the general public will likely only come in the next two years, Hussey cautions: "I think getting the vaccine is a simple thing.
"Getting the vaccine out to the people who need it is the challenge and we don't have a great track record in even getting routine vaccines to the communities that need them most."
*This story has been updated with latest information related to the Moderna vaccine candidate,
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