COVID-19 vaccines for humans number 30, while only three vaccines are available for animals, even though many species have been infected.
“Several animal species have been predicted and found to be susceptible to SARS-CoV-2,” says Suresh V. Kuchipudi, interim director of the Animal Diagnostic Laboratory at the Huck Institutes of Life Sciences. But the risk remains unknown for many animals in several parts of the world, he says. “Therefore, there is an urgent need to monitor the SARS-CoV-2 exposure of high-risk animals in different parts of the world.”
In June, India introduced Ancovax, its first COVID-19 vaccine for animals. The development came a year after the nation reported that the virus had infected eight Asiatic lions, with two of them dying. While 30 COVID-19 vaccines for humans have been approved for general or emergency use across the world, Ancovax is only the third such vaccine for animals. The first, named Carnivac-Cov, was registered by Russia in March last year, followed by another vaccine four months later, developed by Zoetis, a U.S. pharmaceutical company.
Christina Lood, a Zoetis spokesperson, says the company has donated over 26,000 doses of its animal vaccine to over 200 zoos – in addition to 20 conservatories, sanctuaries and other animal organizations located in over a dozen countries, including Canada, Chile and the U.S. The vaccine, she adds, has been administered to more than 300 mammalian species so far.
“At least 75 percent of emerging infectious diseases have an animal origin, including COVID-19,” says Lood. “Now more than ever before, we can all see the important connection between animal health and human health."
The Dangers of COVID-19 Infections among Animals
Cases of the virus in animals have been reported in several countries across the world. As of March this year, 29 kinds of animals have been infected. These include pet animals like dogs, cats, ferrets and hamsters; farmed animals like minks; wild animals like the white-tailed deer, mule deer and black-tailed marmoset; and animals in zoos and sanctuaries, including hyenas, hippopotamuses and manatees. Despite the widespread infection, the U.S. Centres for Diseases Control and Prevention (CDC) has noted that “we don’t yet know all of the animals that can get infected,” adding that more studies and surveillance are needed to understand how the virus is spread between humans and animals.
Leyi Wang, a veterinary virologist at the Veterinary Diagnostic Laboratory, University of Illinois, says that captive and pet animals most often get infected by humans. It goes both ways, he says, citing a recent study in Hong Kong that found the virus spread from pet hamsters to people.
Wang’s bigger concern is the possibility that humans or domestic animals could transmit the virus back to wildlife, creating an uncontrollable reservoir of the disease, especially given the difficulty of vaccinating non-captive wild animals. Such spillbacks have happened previously with diseases such as plague, yellow-fever, and rabies.
It’s challenging and expensive to develop and implement animal vaccines, and demand has been lacking as the broader health risk for animals isn’t well known among the public. People tend to think only about their house pets.
In the past, other human respiratory viruses have proven fatal for endangered great apes like chimpanzees and gorillas. Fearing that COVID-19 could have the same effect, primatologists have been working to protect primates throughout the pandemic. Meanwhile, virus reservoirs have already been created among other animals, Wang says. “Deer of over 20 U.S. states were tested SARS-CoV-2 positive,” says Wang, pointing to a study that confirmed human-to-deer transmission as well as deer-to-deer transmission. It remains unclear how many wildlife species may be susceptible to the disease due to interaction with infected deer, says Wang.
In April, the CDC expressed concerns over new coronavirus variants mutating in wildlife, urging health authorities to monitor the spread of the contagion in animals as threats to humans. The WHO has made similar recommendations.
Challenges to Vaccine Development
Zoetis initiated development activities for its COVID-19 vaccine in February 2020 when the first known infection of a dog occurred in Hong Kong. The pharmaceutical giant completed the initial development work and studies on dogs and cats, and shared their findings at the World One Health Congress in the fall of 2020. A few months later, after a troop of eight gorillas contracted the virus at the San Diego Zoo Safari Park, Zoetis donated its experimental vaccine for emergency use in the great ape population.
Zoetis has uniquely formulated its COVID-19 vaccine for animals. It uses the same antigen as human vaccines, but it includes a different type of carrier protein for inducing a strong immune response. “The unique combination of antigen and carrier ensures safety and efficacy for the species in which a vaccine is used,” says Lood.
But it’s challenging and expensive to develop and implement animal vaccines, and demand has been lacking as the broader health risk for animals isn’t well known among the public. People tend to think only about their house pets. “As it became apparent that risk of severe disease for household pets such as cats and dogs was low, demand for those vaccines decreased before they became commercially available,” says William Karesh, executive vice-president for health and policy at EcoHealth Alliance. He adds that in affected commercial mink farms, the utility of a vaccine could justify the cost in some cases.
Although scientists have made tremendous advances in making vaccines for animals, Kuchipudi thinks that the need for COVID-19 vaccines for animals “must be evaluated based on many factors, including the susceptibility of the particular animal species, health implications, and cost.”.
Not every scientist feels the need for animal vaccines. Joel Baines, a professor of virology at Cornell University’s Baker Institute for Animal Health, says that while domestic cats are the most susceptible to COVID-19, they usually suffer mild infections. Big cats in zoos are vulnerable, but they can be isolated or distanced from humans. He says that mink farms are a relatively small industry and, by ensuring that human handlers are COVID negative, such outbreaks can be curtailed.
Baines also suggests that human vaccines could probably work in animals, as they were tested in animals during early clinical trials and induced immune responses. “However, these vaccines should be used in humans as a priority and it would be unethical to use a vaccine meant for humans to vaccinate an animal if vaccine doses are at all limiting,” he says.
William Karesh, president of the World Animal Health Organization Working Group on Wildlife Diseases, says the best way to protect animals is to reduce their exposure to infected people.
William Karesh
In the absence of enough vaccines, Karesh says that the best way to protect animals is the same as protecting unvaccinated humans - reduce their exposure to infected people by isolating them when necessary. “People working with or spending time with wild animals should follow available guidelines, which includes testing themselves and wearing PPE to avoid accidentally infecting wildlife,” he says.
The Link between Animal and Human Health
Although there is a need for animal vaccines in response to virus outbreaks, the best approach is to try to prevent the outbreaks in the first place, explains K. Srinath Reddy, president of the Public Health Foundation of India. He says that the incidence of zoonotic diseases has increased in the past six decades because human actions like increased deforestation, wildlife trade and animal meat consumption have opened an ecological window for disease transmission between humans and animals. Such actions chip away at the natural barriers between humans and forest-dwelling viruses, while building conveyor belts for the transmission of zoonotic diseases like COVID-19.
Many studies suggest that the source of COVID-19 was infected live animals sold at a wet market in China’s Wuhan. The market sold live dogs, rats, porcupines, badgers, hares, foxes, hedgehogs, marmots and Chinese muntjac (small deer) and, according to a study published in July, the virus was found on the market’s stalls, animal cages, carts and water drains.
This research strongly suggests that COVID-19 is a zoonotic disease, one that jumps from animals to humans due to our close relationship with them in agriculture, as companions and in the natural environment. Half of the infectious diseases that affect people come from animals, but the study of zoonotic diseases has been historically underfunded, even as they can reduce the likelihood and cost of future pandemics.
“We need to invest in vaccines,” says Reddy, “but that cannot be a substitute for an ecologically sensible approach to curtailing zoonotic diseases.”
NASA astronaut Frank Rubio floats by the International Space Station’s “window to the world.” Yesterday, he returned from the longest single spaceflight by a U.S. astronaut on record - over one year. Exploring deep space will require even longer missions.
Yesterday, NASA astronaut Frank Rubio returned to Earth after over one year, the longest single spaceflight for a U.S. astronaut. But this is just the start; longer and more complex missions into deep space loom ahead, from returning to the moon in 2025 to eventually sending humans to Mars. To ensure that these missions succeed, NASA is increasing efforts to study the biological effects and prevent harm.
The dangers of microgravity are real
A NASA report published in 2016 details a long list of incidents and near-misses caused – at least partly – by space-induced changes in astronauts’ vision and coordination. These issues make it harder to move with precision and to judge distance and velocity.
According to the report, in 1997, a resupply ship collided with the Mir space station, possibly because a crew member bumped into the commander during the final docking maneuver. This mishap caused significant damage to the space station.
Returns to Earth suffered from problems, too. The same report notes that touchdown speeds during the first 100 space shuttle landings were “outside acceptable limits. The fastest landing on record – 224 knots (258 miles) per hour – was linked to the commander’s momentary spatial disorientation.” Earlier, each of the six Apollo crews that landed on the moon had difficulty recognizing moon landmarks and estimating distances. For example, Apollo 15 landed in an unplanned area, ultimately straddling the rim of a five-foot deep crater on the moon, harming one of its engines.
Spaceflight causes unique stresses on astronauts’ brains and central nervous systems. NASA is working to reduce these harmful effects.
NASA
Space messes up your brain
In space, astronauts face the challenges of microgravity, ionizing radiation, social isolation, high workloads, altered circadian rhythms, monotony, confined living quarters and a high-risk environment. Among these issues, microgravity is one of the most consequential in terms of physiological changes. It changes the brain’s structure and its functioning, which can hurt astronauts’ performance.
The brain shifts upwards within the skull, displacing the cerebrospinal fluid, which reduces the brain’s cushioning. Essentially, the brain becomes crowded inside the skull like a pair of too-tight shoes.
That’s partly because of how being in space alters blood flow. On Earth, gravity pulls our blood and other internal fluids toward our feet, but our circulatory valves ensure that the fluids are evenly distributed throughout the body. In space, there’s not enough gravity to pull the fluids down, and they shift up, says Rachael D. Seidler, a physiologist specializing in spaceflight at the University of Florida and principal investigator on many space-related studies. The head swells and legs appear thinner, causing what astronauts call “puffy face chicken legs.”
“The brain changes at the structural and functional level,” says Steven Jillings, equilibrium and aerospace researcher at the University of Antwerp in Belgium. “The brain shifts upwards within the skull,” displacing the cerebrospinal fluid, which reduces the brain’s cushioning. Essentially, the brain becomes crowded inside the skull like a pair of too-tight shoes. Some of the displaced cerebrospinal fluid goes into cavities within the brain, called ventricles, enlarging them. “The remaining fluids pool near the chest and heart,” explains Jillings. After 12 consecutive months in space, one astronaut had a ventricle that was 25 percent larger than before the mission.
Some changes reverse themselves while others persist for a while. An example of a longer-lasting problem is spaceflight-induced neuro-ocular syndrome, which results in near-sightedness and pressure inside the skull. A study of approximately 300 astronauts shows near-sightedness affects about 60 percent of astronauts after long missions on the International Space Station (ISS) and more than 25 percent after spaceflights of only a few weeks.
Another long-term change could be the decreased ability of cerebrospinal fluid to clear waste products from the brain, Seidler says. That’s because compressing the brain also compresses its waste-removing glymphatic pathways, resulting in inflammation, vulnerability to injuries and worsening its overall health.
The effects of long space missions were best demonstrated on astronaut twins Scott and Mark Kelly. This NASA Twins Study showed multiple, perhaps permanent, changes in Scott after his 340-day mission aboard the ISS, compared to Mark, who remained on Earth. The differences included declines in Scott’s speed, accuracy and cognitive abilities that persisted longer than six months after returning to Earth in March 2016.
By the end of 2020, Scott’s cognitive abilities improved, but structural and physiological changes to his eyes still remained, he said in a BBC interview.
“It seems clear that the upward shift of the brain and compression of the surrounding tissues with ventricular expansion might not be a good thing,” Seidler says. “But, at this point, the long-term consequences to brain health and human performance are not really known.”
NASA astronaut Kate Rubins conducts a session for the Neuromapping investigation.
NASA
Staying sharp in space
To investigate how prolonged space travel affects the brain, NASA launched a new initiative called the Complement of Integrated Protocols for Human Exploration Research (CIPHER). “CIPHER investigates how long-duration spaceflight affects both brain structure and function,” says neurobehavioral scientist Mathias Basner at the University of Pennsylvania, a principal investigator for several NASA studies. “Through it, we can find out how the brain adapts to the spaceflight environment and how certain brain regions (behave) differently after – relative to before – the mission.”
To do this, he says, “Astronauts will perform NASA’s cognition test battery before, during and after six- to 12-month missions, and will also perform the same test battery in an MRI scanner before and after the mission. We have to make sure we better understand the functional consequences of spaceflight on the human brain before we can send humans safely to the moon and, especially, to Mars.”
As we go deeper into space, astronauts cognitive and physical functions will be even more important. “A trip to Mars will take about one year…and will introduce long communication delays,” Seidler says. “If you are on that mission and have a problem, it may take eight to 10 minutes for your message to reach mission control, and another eight to 10 minutes for the response to get back to you.” In an emergency situation, that may be too late for the response to matter.
“On a mission to Mars, astronauts will be exposed to stressors for unprecedented amounts of time,” Basner says. To counter them, NASA is considering the continuous use of artificial gravity during the journey, and Seidler is studying whether artificial gravity can reduce the harmful effects of microgravity. Some scientists are looking at precision brain stimulation as a way to improve memory and reduce anxiety due to prolonged exposure to radiation in space.
Other scientists are exploring how to protect neural stem cells (which create brain cells) from radiation damage, developing drugs to repair damaged brain cells and protect cells from radiation.
To boldly go where no astronauts have gone before, they must have optimal reflexes, vision and decision-making. In the era of deep space exploration, the brain—without a doubt—is the final frontier.
Additionally, NASA is scrutinizing each aspect of the mission, including astronaut exercise, nutrition and intellectual engagement. “We need to give astronauts meaningful work. We need to stimulate their sensory, cognitive and other systems appropriately,” Basner says, especially given their extreme confinement and isolation. The scientific experiments performed on the ISS – like studying how microgravity affects the ability of tissue to regenerate is a good example.
“We need to keep them engaged socially, too,” he continues. The ISS crew, for example, regularly broadcasts from space and answers prerecorded questions from students on Earth, and can engage with social media in real time. And, despite tight quarters, NASA is ensuring the crew capsule and living quarters on the moon or Mars include private space, which is critical for good mental health.
Exploring deep space builds on a foundation that began when astronauts first left the planet. With each mission, scientists learn more about spaceflight effects on astronauts’ bodies. NASA will be using these lessons to succeed with its plans to build science stations on the moon and, eventually, Mars.
“Through internally and externally led research, investigations implemented in space and in spaceflight simulations on Earth, we are striving to reduce the likelihood and potential impacts of neurostructural changes in future, extended spaceflight,” summarizes NASA scientist Alexandra Whitmire. To boldly go where no astronauts have gone before, they must have optimal reflexes, vision and decision-making. In the era of deep space exploration, the brain—without a doubt—is the final frontier.
Swiss researchers have found a type of brain cell that appears to be a hybrid of the two other main types — and it could lead to new treatments for brain disorders.
A new brain cell: Researchers at the Wyss Center for Bio and Neuroengineering and the University of Lausanne believe they’ve definitively proven that some astrocytes do actively participate in neurotransmission, making them a sort of hybrid of neurons and glial cells.
According to the researchers, this third type of brain cell, which they call a “glutamatergic astrocyte,” could offer a way to treat Alzheimer’s, Parkinson’s, and other disorders of the nervous system.
“Its discovery opens up immense research prospects,” said study co-director Andrea Volterra.
The study: Neurotransmission starts with a neuron releasing a chemical called a neurotransmitter, so the first thing the researchers did in their study was look at whether astrocytes can release the main neurotransmitter used by neurons: glutamate.
By analyzing astrocytes taken from the brains of mice, they discovered that certain astrocytes in the brain’s hippocampus did include the “molecular machinery” needed to excrete glutamate. They found evidence of the same machinery when they looked at datasets of human glial cells.
Finally, to demonstrate that these hybrid cells are actually playing a role in brain signaling, the researchers suppressed their ability to secrete glutamate in the brains of mice. This caused the rodents to experience memory problems.
“Our next studies will explore the potential protective role of this type of cell against memory impairment in Alzheimer’s disease, as well as its role in other regions and pathologies than those explored here,” said Andrea Volterra, University of Lausanne.
But why? The researchers aren’t sure why the brain needs glutamatergic astrocytes when it already has neurons, but Volterra suspects the hybrid brain cells may help with the distribution of signals — a single astrocyte can be in contact with thousands of synapses.
“Often, we have neuronal information that needs to spread to larger ensembles, and neurons are not very good for the coordination of this,” researcher Ludovic Telley told New Scientist.
Looking ahead: More research is needed to see how the new brain cell functions in people, but the discovery that it plays a role in memory in mice suggests it might be a worthwhile target for Alzheimer’s disease treatments.
The researchers also found evidence during their study that the cell might play a role in brain circuits linked to seizures and voluntary movements, meaning it’s also a new lead in the hunt for better epilepsy and Parkinson’s treatments.
“Our next studies will explore the potential protective role of this type of cell against memory impairment in Alzheimer’s disease, as well as its role in other regions and pathologies than those explored here,” said Volterra.
