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Fossil bones collected in the early 1990s on Henderson Island, part of the Pitcairn Group, have revealed a new species of Polynesian sandpiper.

• 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 was produced by the Bhekisisa Centre for Health Journalism. Sign up for the newsletter.

*This story has been updated with latest information related to the Moderna vaccine candidate,

^{Image credit: Getty Images}

Aisha Abdool Karim

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• Eating more at breakfast and less at dinner was previously seen as beneficial
• Studies were conducted indicating that this could help with weight loss
• Recent research, however, shows otherwise

There are many theories around when and what one should eat in order to lose or maintain weight. One widely-accepted belief is that we must eat breakfast and that most of our daily calories should be consumed at breakfast. 

This idea is backed by numerous studies, one of which concluded: “High-calorie breakfast with reduced intake at dinner is beneficial and might be a useful alternative for the management of obesity and metabolic syndrome.”

Ground-breaking research presented on 13 November at the American Heart Association’s Scientific Sessions 2020, however, proves otherwise.

Author of the study and associate professor at John Hopkins University, Nisa M. Maruthur stated: “We have wondered for a long time if when one eats during the day affects the way the body uses and stores energy.” 

This led Maruthur and a team of her colleagues to conduct a study investigating whether restricting meals to early in the day would facilitate weight loss.

Time-restricted eating patterns

The study involved 41 adults with a BMI that classified them as being overweight. Ninety percent of the participants were Black women who were either diabetic or prediabetic. Twenty-one of the participants were assigned to a time-restricted eating plan which limited them to eating at specific hours only, and they had to eat 80% of their daily calories before 13:00.

The remaining 20 adults ate at usual times but consumed 50% of their daily calories after 17:00. Weight and blood pressure of the participants were measured at four-week intervals.

The researchers hypothesised that participants following a time-restricted feeding pattern would lose more weight than those following a more traditional eating pattern.

Eating times not deciding factors for weight loss

Researchers were stunned by the results of the study, which found that across both groups people lost weight and their blood pressure decreased regardless of when they ate. 

According to Maruthur, “Most prior studies have not controlled the number of calories, so it wasn’t clear if people who ate earlier just ate fewer calories. In this study, the only thing we changed was the time of day of eating.”

These results prove that you won’t necessarily gain weight if you were to eat bigger meals later in the day compared to eating a larger number of calories in the morning.

^{Image credit: iStock}

Compiled by Virginia Van Wyk

• It’s been confirmed that SARS-CoV-2 has mutated in a way that’s enabled it to spread more quickly 
• However, the spike mutation may also make the virus more susceptible to a vaccine
• As the study was not carried out on humans, additional studies are needed to track the consequences of these mutations 

The new coronavirus has a complex biology, and, according to ScienceMag, accumulates about two changes per month in its genome (the genetic material).

Now, a new study by scientists from the University of North Carolina at Chapel Hill and the University of Wisconsin-Madison has revealed that, while SARS-CoV-2 has mutated in a way that’s enabled it to be more infectious than other coronaviruses, the spike mutation may also make it more susceptible to a vaccine.

The findings, published in Science, note that the new strain, called D614G, emerged in Europe and has become the most common in the world. 

Strain more sensitive to neutralisation 

“The D614G virus outcompetes and outgrows the ancestral strain by about 10-fold and replicates extremely efficiently in primary nasal epithelial cells, which are a potentially important site for person-to-person transmission,” study author Ralph Baric, professor of epidemiology at the UNC-Chapel Hill Gillings School of Global Public Health and professor of microbiology and immunology at the UNC School of Medicine, said in a UNC news release.

However, despite the D614G strain replicating faster and becoming the most common worldwide, the research team found that it is slightly more sensitive to neutralisation by antibody drugs.

Baric has studied coronaviruses for more than three decades. He was also integral in the development of remdesivir, the first FDA-approved treatment for Covid-19. 

Why does the strain dominate?

Researchers believe the D614G strain dominates because it increases the spike protein’s ability to open cells for the virus to enter.

“The original spike protein had a ‘D’ at this position, and it was replaced by a ‘G’,” said Yoshihiro Kawaoka, a virologist at the University of Wisconsin-Madison.” Several papers had already described that this mutation makes the protein more functional and more efficient at getting into cells.”

The newly discovered mutation causes a flap on the tip of one spike to pop open, the researchers explained, thereby allowing the virus to infect cells more efficiently. It also creates a pathway to the virus’s vulnerable core, they said.

On the bright side, with one flap open, it’s also easier for antibodies, such as the ones currently being tested in vaccines, to infiltrate and disable the virus.

For this study, the researchers ran hamster experiments and performed replication and airborne transmission studies with both the original virus and the mutated version created by the team.

“We saw that the mutant virus transmits better airborne than the [original] virus, which may explain why this virus dominated in humans,” said Kawaoka.

Pathology also examined

In addition to the above, the researchers also looked at the pathology of the two coronavirus strains.

After infection, the hamsters displayed more or less the same viral load and symptoms, suggesting that while the mutant virus is much better at infecting hosts, it doesn’t cause significantly worse illness.

However, the researchers caution that these results may not reflect in human studies.

“SARS-CoV-2 is an entirely new human pathogen and its evolution in human populations is hard to predict,” Baric said.

“New variants are continually emerging, like the recently discovered mink SARS-CoV-2 cluster 5 variant in Denmark that also encodes D614G.

“To maximally protect public health, we must continue to track and understand the consequences of these new mutations on disease severity, transmission, host range and vulnerability to vaccine-induced immunity,” he commented.

READ | Does it matter that the Covid-19 virus is mutating?

READ | Mutation helps coronavirus infect more human cells, study shows

READ | How genetic mutations in healthy young men made them susceptible to severe Covid-19

^{Image credit: Getty/Peter Zelei Images}

Compiled by Zakiyah Ebrahim

Prof Ugur Sahin also raises hopes the vaccine, developed with Pfizer. could halve Covid transmission.