Novel Technologies Could Make Coronavirus Vaccines More Stable for Worldwide Shipping
Ssendi Bosco has long known to fear the rainy season. As deputy health officer of Mubende District, a region in Central Uganda, she is only too aware of the threat that heavy storms can pose to her area's fragile healthcare facilities.
In early October, persistent rain overwhelmed the power generator that supplies electricity to most of the region, causing a blackout for three weeks. The result was that most of Mubende's vaccine supplies against diseases such as tuberculosis, diphtheria, and polio went to waste. "The vaccines need to be constantly refrigerated, so the generator failing means that most of them are now unusable," she says.
This week, the global fight against the coronavirus pandemic received a major boost when Pfizer and their German partner BioNTech released interim results showing that their vaccine has proved more than 90 percent effective at preventing participants in their clinical trial from getting COVID-19.
But while Pfizer has already signed deals to supply the vaccine to the U.S., U.K., Canada, Japan and the European Union, Mubende's recent plight provides an indication of the challenges that distributors will face when attempting to ship a coronavirus vaccine around the globe, particularly to low-income nations.
Experts have estimated that somewhere between 12 billion and 15 billion doses will be needed to immunize the world's population against COVID-19, a staggering scale, and one that has never been attempted before. "The logistics of distributing COVID-19 vaccines have been described as one of the biggest challenges in the history of mankind," says Göran Conradson, managing director of Swedish vaccine manufacturer Ziccum.
But even these estimates do not take into account the potential for vaccine spoilage. Every year, the World Health Organization estimates that over half of the world's vaccines end up being wasted. This happens because vaccines are fragile products. From the moment they are made, to the moment they are administered, they have to be kept within a tightly controlled temperature range. Throughout the entire supply chain – transportation to an airport, the flight to another country, unloaded, distribution via trucks to healthcare facilities, and storage – they must be refrigerated at all times. This is known as the cold chain, and one tiny slip along the way means the vaccines are ruined.
"It's a chain, and any chain is only as strong as its weakest link," says Asel Sartbaeva, a chemist working on vaccine technologies at the University of Bath in the U.K.
For COVID-19, the challenge is even greater because some of the leading vaccine candidates need to be kept at ultracold temperatures. Pfizer's vaccine, for example, must be kept at -70 degrees Celsius, the kind of freezer capabilities rarely found outsides of specialized laboratories. Transporting such a vaccine across North America and Europe will be difficult enough, but supplying it to some of the world's poorest nations in Asia, Africa and South America -- where only 10 percent of healthcare facilities have reliable electricity -- might appear virtually impossible.
But technology may be able to come to the rescue.
Making Vaccines Less Fragile
Just as the world's pharmaceutical companies have been racing against the clock to develop viable COVID-19 vaccine candidates, scientists around the globe have been hastily developing new technologies to try and make vaccines less fragile. Some approaches involve various chemicals that can be added to the vaccine to make them far more resilient to temperature fluctuations during transit, while others focus on insulated storage units that can maintain the vaccine at a certain temperature even if there is a power outage.
Some of these concepts have already been considered for several years, but before COVID-19 there was less of a commercial incentive to bring them to market. "We never felt that there is a need for an investment in this area," explains Sam Kosari, a pharmacist at the University of Canberra, who researches the vaccine cold chain. "Some technologies were developed then to assist with vaccine transport in Africa during Ebola, but since that outbreak was contained, there hasn't been any serious initiative or reward to develop this technology further."
In her laboratory at the University of Bath, Sartbaeva is using silica - the main constituent of sand – to encase the molecular components within a vaccine. Conventional vaccines typically contain protein targets from the virus, which the immune system learns to recognize. However, when they are exposed to temperature changes, these protein structures degrade, and lose their shape, making the vaccine useless. Sartbaeva compares this to how an egg changes its shape and consistency when it is boiled.
When silica is added to a vaccine, it molds to each protein, forming little protective cages around them, and thus preventing them from being affected by temperature changes. "The whole idea is that if we can create a shell around each protein, we can protect it from physically unravelling which is what causes the deactivation of the vaccine," she says.
Other scientists are exploring similar methods of making vaccines more resilient. Researchers at the Jenner Institute at the University of Oxford recently conducted a clinical trial in which they added carbohydrates to a dengue vaccine, to assess whether it became easier to transport.
Both research groups are now hoping to collaborate with the COVID-19 vaccine candidates being developed by AstraZeneca and Imperial College, assuming they become available in 2021.
"It's good we're all working on this big problem, as different methods could work better for different types of COVID-19 vaccines," says Sartbaeva. "I think it will be needed."
Next-Generation Vaccine Technology
While these different technologies could be utilized to try and protect the first wave of COVID-19 vaccines, efforts are also underway to develop completely new methods of vaccination. Much of this research is still in its earliest stages, but it could yield a second generation of COVID-19 vaccine candidates in 2022 and beyond.
"After the first round of mass vaccination, we could well observe regional outbreaks of the disease appearing from time to time in the coming years," says Kosari. "This is the time where new types of vaccines could be helpful."
One novel method being explored by Ziccum and others is dry powder vaccines. The idea is to spray dry the final vaccine into a powder form, where it is more easily preserved and does not require any special cooling while being transported or stored. People then receive the vaccine by inhaling it, rather than having it injected into their bloodstream.
Conradson explains that the concept of dry powder vaccines works on the same principle as dried food products. Because there is no water involved, the vaccine's components are far less affected by temperature changes. "It is actually the water that leads to the destruction of potency of a vaccine when it gets heated," he says. "We're looking to develop a dry powder vaccine for COVID-19 but this will be a second-generation vaccine. At the moment there are more than 200 first-generation candidates, all of which are using conventional technologies due to the timeframe pressures, which I think was the correct decision."
Dry powder COVID-19 vaccines could also be combined with microneedle patches, to allow people to self-administer the vaccine themselves in their own home. Microneedles are miniature needles – measured in millionths of a meter – which are designed to deliver medicines through the skin with minimal pain. So far, they have been used mainly in cosmetic products, but many scientists are working to use them to deliver drugs or vaccines.
At Georgia Institute of Technology in Atlanta, Mark Prausnitz is leading a couple of projects looking at incorporating COVID-19 vaccines into microneedle patches with the hope of running some early-stage clinical trials over the next couple of years. "The advantage is that they maintain the vaccine in a stable, dry state until it dissolves in the skin," he explains.
Prausnitz and others believe that once the first generation of COVID-19 vaccines become available, biotech and pharmaceutical companies will show more interest in adapting their products so they can be used in a dried form or with a microneedle patch. "There is so much pressure to get the COVID vaccine out that right now, vaccine developers are not interested in incorporating a novel delivery method," he says. "That will have to come later, once the pressure is lessened."
The Struggle of Low-Income Nations
For low-income nations, time will only tell whether technological advancements can enable them to access the first wave of licensed COVID-19 vaccines. But reports already suggest that they are in danger of becoming an afterthought in the race to procure vaccine supplies.
While initiatives such as COVAX are attempting to make sure that vaccine access is equitable, high and middle-income countries have already inked deals to secure 3.8 billion doses, with options for another 5 billion. One particularly sobering study by the Duke Global Health Innovation Center has suggested that such hoarding means many low-income nations may not receive a vaccine until 2024.
For Bosco and the residents of Mubende District in Uganda, all they can do is wait. In the meantime, there is a more pressing problem: fixing their generators. "We hope that we can receive a vaccine," she says. "But the biggest problem will be finding ways to safely store it. Right now we cannot keep any medicines or vaccines in the conditions they need, because we don't have the funds to repair our power generators."
Two-and-a-half year-old Huckleberry, a blue merle Australian shepherd, pulls hard at her leash; her yelps can be heard by skiers and boarders high above on the chairlift that carries them over the ski patrol hut to the top of the mountain. Huckleberry is an avalanche rescue dog — or avy dog, for short. She lives and works with her owner and handler, a ski patroller at Breckenridge Ski Resort in Colorado. As she watches the trainer play a game of hide-and-seek with six-month-old Lume, a golden retriever and avy dog-in-training, Huckleberry continues to strain on her leash; she loves the game. Hide-and-seek is one of the key training methods for teaching avy dogs the rescue skills they need to find someone caught in an avalanche — skier, snowmobiler, hiker, climber.
Lume’s owner waves a T-shirt in front of the puppy. While another patroller holds him back, Lume’s owner runs away and hides. About a minute later — after a lot of barking — Lume is released and commanded to “search.” He springs free, running around the hut to find his owner who reacts with a great amount of excitement and fanfare. Lume’s scent training will continue for the rest of the ski season (Breckenridge plans operating through May or as long as weather permits) and through the off-season. “We make this game progressively harder by not allowing the dog watch the victim run away,” explains Dave Leffler, Breckenridge's ski patroller and head of the avy dog program, who has owned, trained and raised many of them. Eventually, the trainers “dig an open hole in the snow to duck out of sight and gradually turn the hole into a cave where the dog has to dig to get the victim,” explains Leffler.
By the time he is three, Lume, like Huckleberry, will be a fully trained avy pup and will join seven other avy dogs on Breckenridge ski patrol team. Some of the team members, both human and canine, are also certified to work with Colorado Rapid Avalanche Deployment, a coordinated response team that works with the Summit County Sheriff’s office for avalanche emergencies outside of the ski slopes’ boundaries.
There have been 19 avalanche deaths in the U.S. this season, according to avalanche.org, which tracks slides; eight in Colorado. During the entirety of last season there were 17. Avalanche season runs from November through June, but avalanches can occur year-round.
High tech and high stakes
Complementing avy dogs’ ability to smell people buried in a slide, avalanche detection, rescue and recovery is becoming increasingly high tech. There are transceivers, signal locators, ground scanners and drones, which are considered “games changers” by many in avalanche rescue and recovery
For a person buried in an avalanche, the chance of survival plummets after 20 minutes, so every moment counts.
A drone can provide thermal imaging of objects caught in a slide; what looks like a rock from far away might be a human with a heat signature. Transceivers, also known as beacons, send a signal from an avalanche victim to a companion. Signal locators, like RECCO reflectors which are often sewn directly into gear, can echo back a radar signal sent by a detector; most ski resorts have RECCO detector units.
Research suggests that Ground Penetrating Radar (GPR), an electromagnetic tool used by geophysicists to pull images from inside the ground, could be used to locate an avalanche victim. A new study from the Department of Energy’s Sandia National Laboratories suggests that a computer program developed to pinpoint the source of a chemical or biological terrorist attack could also be used to find someone submerged in an avalanche. The search algorithm allows for small robots (described as cockroach-sized) to “swarm” a search area. Researchers say that this distributed optimization algorithm can help find avalanche victims four times faster than current search mechanisms. For a person buried in an avalanche, the chance of survival plummets after 20 minutes, so every moment counts.
An avy dog in training is picking up scent
Sarah McLear
While rescue gear has been evolving, predicting when a slab will fall remains an emerging science — kind of where weather forecasting science was in the 1980s. Avalanche forecasting still relies on documenting avalanches by going out and looking,” says Ethan Greene, director of the Colorado Avalanche Information Center (CAIC). “So if there's a big snowstorm, and as you might remember, most avalanches happened during snowstorms, we could have 10,000 avalanches that release and we document 50,” says Greene. “Avalanche forecasting is essentially pattern recognition,” he adds--and understanding the layering structure of snow.
However, determining where the hazards lie can be tricky. While a dense layer of snow over a softer, weaker layer may be a recipe for an avalanche, there’s so much variability in snowpack that no one formula can predict the trigger. Further, observing and measuring snow at a single point may not be representative of all nearby slopes. Finally, there’s not enough historical data to help avalanche scientists create better prediction models.
That, however, may be changing.
Last year, an international group of researchers created computer simulations of snow cover using 16 years of meteorological data to forecast avalanche hazards, publishing their research in Cold Regions Science and Technology. They believe their models, which categorize different kinds of avalanches, can support forecasting and determine whether the avalanche is natural (caused by temperature changes, wind, additional snowfall) or artificial (triggered by a human or animal).
With smell receptors ranging from 800 million for an average dog, to 4 billion for scent hounds, canines remain key to finding people caught in slides.
With data from two sites in British Columbia and one in Switzerland, researchers built computer simulations of five different avalanche types. “In terms of real time avalanche forecasting, this has potential to fill in a lot of data gaps, where we don't have field observations of what the snow looks like,” says Simon Horton, a postdoctoral fellow with the Simon Fraser University Centre for Natural Hazards Research and a forecaster with Avalanche Canada, who participated in the study. While complex models that simulate snowpack layers have been around for a few decades, they weren’t easy to apply until recently. “It's been difficult to find out how to apply that to actual decision-making and improving safety,” says Horton. If you can derive avalanche problem types from simulated snowpack properties, he says, you’ll learn “a lot about how you want to manage that risk.”
The five categories include “new snow,” which is unstable and slides down the slope, “wet snow,” when rain or heat makes it liquidly, as well as “wind-drifted snow,” “persistent weak layers” and “old snow.” “That's when there's some type of deeply buried weak layer in the snow that releases without any real change in the weather,” Horton explains. “These ones tend to cause the most accidents.” One step by a person on that structurally weak layer of snow will cause a slide. Horton is hopeful that computer simulations of avalanche types can be used by scientists in different snow climates to help predict hazard levels.
Greene is doubtful. “If you have six slopes that are lined up next to each other, and you're going to try to predict which one avalanches and the exact dimensions and what time, that's going to be really hard to do. And I think it's going to be a long time before we're able to do that,” says Greene.
What both researchers do agree on, though, is that what avalanche prediction really needs is better imagery through satellite detection. “Just being able to count the number of avalanches that are out there will have a huge impact on what we do,” Greene says. “[Satellites] will change what we do, dramatically.” In a 2022 paper, scientists at the University of Aberdeen in England used satellites to study two deadly Himalayan avalanches. The imaging helped them determine that sediment from a 2016 ice avalanche plus subsequent snow avalanches contributed to the 2021 avalanche that caused a flash flood, killing over 200 people. The researchers say that understanding the avalanches characteristics through satellite imagery can inform them how one such event increases the magnitude of another in the same area.
Avy dogs trainers hide in dug-out holes in the snow, teaching the dogs to find buried victims
Sarah McLear
Lifesaving combo: human tech and Mother Nature’s gear
Even as avalanche forecasting evolves, dogs with their built-in rescue mechanisms will remain invaluable. With smell receptors ranging from 800 million for an average dog, to 4 billion for scent hounds, canines remain key to finding people caught in slides. (Humans in comparison, have a meager 12 million.) A new study published in the Journal of Neuroscience revealed that in dogs smell and vision are connected in the brain, which has not been found in other animals. “They can detect the smell of their owner's fingerprints on a glass slide six weeks after they touched it,” says Nicholas Dodman, professor emeritus at Cummings School of Veterinary Medicine at Tufts University. “And they can track from a boat where a box filled with meat was buried in the water, 100 feet below,” says Dodman, who is also co-founder and president of the Center for Canine Behavior Studies.
Another recent study from Queens College in Belfast, United Kingdom, further confirms that dogs can smell when humans are stressed. They can also detect the smell of a person’s breath and the smell of the skin cells of a deceased person.
The emerging avalanche-predicting human-made tech and the incredible nature-made tech of dogs’ olfactory talents is the lifesaving “equipment” that Leffler believes in. Even when human-made technology develops further, it will be most efficient when used together with the millions of dogs’ smell receptors, Leffler believes. “It is a combination of technology and the avalanche dog that will always be effective in finding an avalanche victim.”
Living with someone changes your microbiome, new research shows
Some roommate frustration can be expected, whether it’s a sink piled high with crusty dishes or crumbs where a clean tabletop should be. Now, research suggests a less familiar issue: person-to-person transmission of shared bacterial strains in our gut and oral microbiomes. For the first time, the lab of Nicola Segata, a professor of genetics and computational biology at the University of Trento, located in Italy, has shown that bacteria of the microbiome are transmitted between many individuals, not just infants and their mothers, in ways that can’t be explained by their shared diet or geography.
It’s a finding with wide-ranging implications, yet frustratingly few predictable outcomes. Our microbiomes are an ever-growing and changing collection of helpful and harmful bacteria that we begin to accumulate the moment we’re born, but experts are still struggling to unravel why and how bacteria from one person’s gut or mouth become established in another person’s microbiome, as opposed to simply passing through.
“If we are looking at the overall species composition of the microbiome, then there is an effect of age of course, and many other factors,” Segata says. “But if we are looking at where our strains are coming from, 99 percent of them are only present in other people’s guts. They need to come from other guts.”
If we could better understand this process, we might be able to control and use it; perhaps hospital patients could avoid infections from other patients when their microbiome is depleted by antibiotics and their immune system is weakened, for example. But scientists are just beginning to link human microbiomes with various ailments. Growing evidence shows that our microbiomes steer our long-term health, impacting conditions like obesity, irritable bowel syndrome, type 2 diabetes, and cancer.
Previous work from Segata’s lab and others illuminated the ways bacteria are passed from mothers to infants during the first few months of life during vaginal birth, breastfeeding and other close contact. And scientists have long known that people in close proximity tend to share bacteria. But the factors related to that overlap, such as genetics and diet, were unclear, especially outside the mother-baby dyad.
“If we look at strain sharing between a mother and an infant at five years of age, for example, we cannot really tell which was due to transmission at birth and which is due to continued transmission because of contact,” Segata says. Experts hypothesized that they could be caused by bacterial similarities in the environment itself, genetics, or bacteria from shared foods that colonized the guts of people in close contact.
Strain sharing was highest in mother-child pairs, with 96 percent of them sharing strains, and only slightly lower in members of shared households, at 95 percent.
In Italy, researchers led by Mireia Valles-Colomer, including Segata, hoped to unravel this mystery. They compared data from 9,715 stool and saliva samples in 31 genomic datasets with existing metadata. Scientists zoomed in on variations in each bacterial strain down to the individual level. They examined not only mother-child pairs, but people living in the same household, adult twins, and people living in the same village in a level of detail that wasn’t possible before, due to its high cost and difficulties in retrieving data about interactions between individuals, Segata explained.
“This paper is, with high granularity, quantifying the percent sharing that you expect between different types of social interactions, controlling for things like genetics and diet,” Gibbons says. Strain sharing was highest in mother-child pairs, with 96 percent of them sharing strains, and only slightly lower in members of shared households, at 95 percent. And at least half of the mother-infant pairs shared 30 percent of their strains; the median was 12 percent among people in shared households. Yet, there was no sharing among eight percent of adult twins who lived separately, and 16 percent of people within villages who resided in different households. The results were published in Nature.
It’s not a regional phenomenon. Although the types of bacterial strains varied depending on whether people lived in western and eastern nations — datasets were drawn from 20 countries on five continents — the patterns of sharing were much the same. To establish these links, scientists focused on individual variations in shared bacterial strains, differences that create unique bacterial “fingerprints” in each person, while controlling for variables like diet, demonstrating that the bacteria had been transmitted between people and were not the result of environmental similarities.
The impact of this bacterial sharing isn’t clear, but shouldn’t be viewed with trepidation, according to Sean Gibbons, a microbiome scientist at the nonprofit Institute for Systems Biology.
“The vast majority of these bugs are actually either benign or beneficial to our health, and the fact that we're swapping and sharing them and that we can take someone else's strain and supplement or better diversify our own little garden is not necessarily a bad thing,” he says.
"There are hundreds of billions of dollars of investment capital moving into these microbiome therapeutic companies; bugs as drugs, so to speak,” says Sean Gibbons, a microbiome scientist at the Institute for Systems Biology.
Everyday habits like exercising and eating vegetables promote a healthy, balanced gut microbiome, which is linked to better metabolic and immune function, and fewer illnesses. While many people’s microbiomes contain bacteria like C. diff or E. coli, these bacteria don’t cause diseases in most cases because they’re present in low levels. But a microbiome that’s been wiped out by, say, antibiotics, may no longer keep these bacteria in check, allowing them to proliferate and make us sick.
“A big challenge in the microbiome field is being able to rationally predict whether, if you're exposed to a particular bug, it will stick in the context of your specific microbiome,” Gibbons says.
Gibbons predicts that explorations of microbe-based therapeutics will be “exploding” in the coming decades. “There are hundreds of billions of dollars of investment capital moving into these microbiome therapeutic companies; bugs as drugs, so to speak,” he says. Rather than taking a mass-marketed probiotic, a precise understanding of an individual’s microbiome could help target the introduction of just the right bacteria at just the right time to prevent or treat a particular illness.
Because the current study did not differentiate between different types of contact or relationships among household members sharing bacterial strains or determine the direction of transmission, Segata says his current project is examining children in daycare settings and tracking their microbiomes over time to understand the role genetics and everyday interactions play in the level of transmission that occurs.
This relatively newfound ability to trace bacterial variants to minute levels has unlocked the chance for scientists to untangle when and how bacteria leap from one microbiome to another. As researchers come to better understand the factors that permit a strain to establish itself within a microbiome, they could uncover new strategies to control these microbes, harnessing the makeup of each microbiome to help people to resist life-altering medical conditions.