Drugs That Could Slow Aging May Hold Promise for Protecting the Elderly from COVID-19
Although recent data has shown the coronavirus poses a greater risk to young people than previously understood, the ensuing COVID-19 disease is clearly far more dangerous for older people than it is for the young.
If we want to lower the COVID-19 fatality rate, we must also make fortifying our most vulnerable hosts a central part of our approach.
While our older adults have accrued tremendous knowledge, wisdom, and perspective over the years, their bodies have over time become less able to fight off viruses and other insults. The shorthand name for this increased susceptibility is aging.
We may have different names for the diseases which disproportionately kill us -- cancer, heart disease, and dementia among them – but what is really killing us is age. The older we are, the greater the chance we'll die from one or another of these afflictions. Eliminate any one completely - including cancer - and we won't on average live that much longer. But if we slow aging on a cellular level, we can counter all of these diseases at once, including COVID-19.
Every army needs both offensive and defensive capabilities. In our war against COVID-19, our offense strategy is to fight the virus directly. But strengthening our defense requires making us all more resistant to its danger. That's why everyone needs to be eating well, exercising, and remaining socially connected. But if we want to lower the COVID-19 fatality rate, we must also make fortifying our most vulnerable hosts a central part of our approach. That's where our new fight against this disease and the emerging science of aging intersect.
Once the domain of charlatans and delusionists, the millennia-old fantasy of extending our healthy lifespans has over the past century become real. But while the big jump in longevity around the world over the past hundred years or so is mostly attributable to advances in sanitation, nutrition, basic healthcare, and worker safety, advances over the next hundred will come from our increasing ability to hack the biology of aging itself.
A few decades ago, scientists began recognizing that some laboratory animals on calorie-restricted diets tended to live healthier, longer lives. Through careful experiments derived from these types of insights, scientists began identifying specific genetic, epigenetic, and metabolic pathways that influence how we age. A range of studies have recently suggested that systemic knobs might metaphorically be turned to slow the cellular aging process, making us better able to fight off diseases and viral attacks.
Among the most promising of these systemic interventions is a drug called metformin, which targets many of the hallmarks of aging and extends health span and lifespan in animals. Metformin has been around since the Middle Ages and has been used in Europe for over 60 years to treat diabetes. This five-cent pill became the most prescribed drug in the world after being approved by the FDA in 1994.
With so many people taking it, ever larger studies began suggesting metformin's positive potential effects preventing diabetes, cardiovascular diseases, cancer, and dementia. In fact, elderly people on metformin for their diabetes have around a 20 percent lower mortality than age-matched subjects without diabetes. Results like these led scientists to hypothesize that metformin wasn't just impacting a few individual diseases but instead having a systemic impact on entire organisms.
Another class of drug that seems to slow the systemic process of aging in animal models and very preliminary human trials inhibits a nutrient-sensing cellular protein called mTOR. A new category of drugs called rapalogues has been shown to extend healthspan and lifespan in every type of non-human animal so far tested. Two recent human studies indicated that rapalogues increased resistance to the flu and decreased the severity of respiratory tract infections in older adults.
If COVID-19 is primarily a severe disease of aging, then countering aging should logically go a long way in countering the disease.
These promising early indications have inspired a recently launched long-term study exploring how metformin and rapalogues might delay the onset of multiple, age-related diseases and slow the biological process of aging in humans. Under normal circumstances, studies like this seeking to crack the biological code of aging would continue to proceed slowly and carefully over years, moving from animal experiments to cautious series of human trials. But with deaths rising by the day, particularly of older people, these are not times for half measures. Wartimes have always demanded new ways of doing important things at warp speeds.
If COVID-19 is primarily a severe disease of aging, then countering aging should logically go a long way in countering the disease. We need to find out. Fast.
Although it would be a mistake for older people to just begin taking drugs like these without any indication, pushing to massively speed up our process for assessing whether these types of interventions can help protect older people is suddenly critical.
To do this, we need U.S. government agencies like the Department of Health and Human Services' Biomedical Advanced Research and Development Authority (BARDA) to step up. BARDA currently only funds COVID-19 clinical trials of drugs that can be dosed once and provide 60 days of protection. Metformin and rapalogues are not considered for BARDA funding because they are dosed once daily. This makes no sense because a drug that provides 60 days of protection from the coronavirus after a single dose does not yet exist, while metformin and rapalogues have already passed extensive safety tests. Instead, BARDA should consider speeding up trials with currently available drugs that could help at least some of the elderly populations at risk.
Although the U.S. Food and Drug Administration and Centers for Disease Control are ramping up their approval processes and even then needs to prioritize efforts, they too must find a better balance between appropriate regulatory caution and the dire necessities of our current moment. Drugs like metformin and rapalogues that have shown preliminary efficacy ought to be fast-tracked for careful consideration.
One day we will develop a COVID-19 vaccine to help everyone. But that could be at least a year from now, if not more. Until we get there and even after we do, speeding up our process of fortifying our older populations mush be a central component of our wartime strategy.
And when the war is won and life goes back to a more normal state, we'll get the added side benefit of a few more months and ultimately years with our parents and grandparents.
How the body's immune resilience affects our health and lifespan
Story by Big Think
It is a mystery why humans manifest vast differences in lifespan, health, and susceptibility to infectious diseases. However, a team of international scientists has revealed that the capacity to resist or recover from infections and inflammation (a trait they call “immune resilience”) is one of the major contributors to these differences.
Immune resilience involves controlling inflammation and preserving or rapidly restoring immune activity at any age, explained Weijing He, a study co-author. He and his colleagues discovered that people with the highest level of immune resilience were more likely to live longer, resist infection and recurrence of skin cancer, and survive COVID and sepsis.
Measuring immune resilience
The researchers measured immune resilience in two ways. The first is based on the relative quantities of two types of immune cells, CD4+ T cells and CD8+ T cells. CD4+ T cells coordinate the immune system’s response to pathogens and are often used to measure immune health (with higher levels typically suggesting a stronger immune system). However, in 2021, the researchers found that a low level of CD8+ T cells (which are responsible for killing damaged or infected cells) is also an important indicator of immune health. In fact, patients with high levels of CD4+ T cells and low levels of CD8+ T cells during SARS-CoV-2 and HIV infection were the least likely to develop severe COVID and AIDS.
Individuals with optimal levels of immune resilience were more likely to live longer.
In the same 2021 study, the researchers identified a second measure of immune resilience that involves two gene expression signatures correlated with an infected person’s risk of death. One of the signatures was linked to a higher risk of death; it includes genes related to inflammation — an essential process for jumpstarting the immune system but one that can cause considerable damage if left unbridled. The other signature was linked to a greater chance of survival; it includes genes related to keeping inflammation in check. These genes help the immune system mount a balanced immune response during infection and taper down the response after the threat is gone. The researchers found that participants who expressed the optimal combination of genes lived longer.
Immune resilience and longevity
The researchers assessed levels of immune resilience in nearly 50,000 participants of different ages and with various types of challenges to their immune systems, including acute infections, chronic diseases, and cancers. Their evaluation demonstrated that individuals with optimal levels of immune resilience were more likely to live longer, resist HIV and influenza infections, resist recurrence of skin cancer after kidney transplant, survive COVID infection, and survive sepsis.
However, a person’s immune resilience fluctuates all the time. Study participants who had optimal immune resilience before common symptomatic viral infections like a cold or the flu experienced a shift in their gene expression to poor immune resilience within 48 hours of symptom onset. As these people recovered from their infection, many gradually returned to the more favorable gene expression levels they had before. However, nearly 30% who once had optimal immune resilience did not fully regain that survival-associated profile by the end of the cold and flu season, even though they had recovered from their illness.
Intriguingly, some people who are 90+ years old still have optimal immune resilience, suggesting that these individuals’ immune systems have an exceptional capacity to control inflammation and rapidly restore proper immune balance.
This could suggest that the recovery phase varies among people and diseases. For example, young female sex workers who had many clients and did not use condoms — and thus were repeatedly exposed to sexually transmitted pathogens — had very low immune resilience. However, most of the sex workers who began reducing their exposure to sexually transmitted pathogens by using condoms and decreasing their number of sex partners experienced an improvement in immune resilience over the next 10 years.
Immune resilience and aging
The researchers found that the proportion of people with optimal immune resilience tended to be highest among the young and lowest among the elderly. The researchers suggest that, as people age, they are exposed to increasingly more health conditions (acute infections, chronic diseases, cancers, etc.) which challenge their immune systems to undergo a “respond-and-recover” cycle. During the response phase, CD8+ T cells and inflammatory gene expression increase, and during the recovery phase, they go back down.
However, over a lifetime of repeated challenges, the immune system is slower to recover, altering a person’s immune resilience. Intriguingly, some people who are 90+ years old still have optimal immune resilience, suggesting that these individuals’ immune systems have an exceptional capacity to control inflammation and rapidly restore proper immune balance despite the many respond-and-recover cycles that their immune systems have faced.
Public health ramifications could be significant. Immune cell and gene expression profile assessments are relatively simple to conduct, and being able to determine a person’s immune resilience can help identify whether someone is at greater risk for developing diseases, how they will respond to treatment, and whether, as well as to what extent, they will recover.
A new injection is helping stave off RSV this season
In November 2021, Mickayla Wininger’s then one-month-old son, Malcolm, endured a terrifying bout with RSV, the respiratory syncytial (sin-SISH-uhl) virus—a common ailment that affects all age groups. Most people recover from mild, cold-like symptoms in a week or two, but RSV can be life-threatening in others, particularly infants.
Wininger, who lives in southern Illinois, was dressing Malcolm for bed when she noticed what seemed to be a minor irregularity with this breathing. She and her fiancé, Gavin McCullough, planned to take him to the hospital the next day. The matter became urgent when, in the morning, the boy’s breathing appeared to have stopped.
After they dialed 911, Malcolm started breathing again, but he ended up being hospitalized three times for RSV and defects in his heart. Eventually, he recovered fully from RSV, but “it was our worst nightmare coming to life,” Wininger recalled.
It’s a scenario that the federal government is taking steps to prevent. In July, the Food and Drug Administration approved a single-dose, long-acting injection to protect babies and toddlers. The injection, called Beyfortus, or nirsevimab, became available this October. It reduces the incidence of RSV in pre-term babies and other infants for their first RSV season. Children at highest risk for severe RSV are those who were born prematurely and have either chronic lung disease of prematurity or congenital heart disease. In those cases, RSV can progress to lower respiratory tract diseases such as pneumonia and bronchiolitis, or swelling of the lung’s small airway passages.
Each year, RSV is responsible for 2.1 million outpatient visits among children younger than five-years-old, 58,000 to 80,000 hospitalizations in this age group, and between 100 and 300 deaths, according to the Centers for Disease Control and Prevention. Transmitted through close contact with an infected person, the virus circulates on a seasonal basis in most regions of the country, typically emerging in the fall and peaking in the winter.
In August, however, the CDC issued a health advisory on a late-summer surge in severe cases of RSV among young children in Florida and Georgia. The agency predicts "increased RSV activity spreading north and west over the following two to three months.”
Infants are generally more susceptible to RSV than older people because their airways are very small, and their mechanisms to clear these passages are underdeveloped. RSV also causes mucus production and inflammation, which is more of a problem when the airway is smaller, said Jennifer Duchon, an associate professor of newborn medicine and pediatrics in the Icahn School of Medicine at Mount Sinai in New York.
In 2021 and 2022, RSV cases spiked, sending many to emergency departments. “RSV can cause serious disease in infants and some children and results in a large number of emergency department and physician office visits each year,” John Farley, director of the Office of Infectious Diseases in the FDA’s Center for Drug Evaluation and Research, said in a news release announcing the approval of the RSV drug. The decision “addresses the great need for products to help reduce the impact of RSV disease on children, families and the health care system.”
Sean O’Leary, chair of the committee on infectious diseases for the American Academy of Pediatrics, says that “we’ve never had a product like this for routine use in children, so this is very exciting news.” It is recommended for all kids under eight months old for their first RSV season. “I would encourage nirsevimab for all eligible children when it becomes available,” O’Leary said.
For those children at elevated risk of severe RSV and between the ages of 8 and 19 months, the CDC recommends one dose in their second RSV season.
The drug will be “really helpful to keep babies healthy and out of the hospital,” said O’Leary, a professor of pediatrics at the University of Colorado Anschutz Medical Campus/Children’s Hospital Colorado in Denver.
An antiviral drug called Synagis (palivizumab) has been an option to prevent serious RSV illness in high-risk infants since it was approved by the FDA in 1998. The injection must be given monthly during RSV season. However, its use is limited to “certain children considered at high risk for complications, does not help cure or treat children already suffering from serious RSV disease, and cannot prevent RSV infection,” according to the National Foundation for Infectious Diseases.
Until the approval this summer of the new monoclonal antibody, nirsevimab, there wasn’t a reliable method to prevent infection in most healthy infants.
Both nirsevimab and palivizumab are monoclonal antibodies that act against RSV. Monoclonal antibodies are lab-made proteins that mimic the immune system’s ability to fight off harmful pathogens such as viruses. A single intramuscular injection of nirsevimab preceding or during RSV season may provide protection.
The strategy with the new monoclonal antibody is “to extend protection to healthy infants who nonetheless are at risk because of their age, as well as infants with additional medical risk factors,” said Philippa Gordon, a pediatrician and infectious disease specialist in Brooklyn, New York, and medical adviser to Park Slope Parents, an online community support group.
No specific preventive measure is needed for older and healthier kids because they will develop active immunity, which is more durable. Meanwhile, older adults, who are also vulnerable to RSV, can receive one of two new vaccines. So can pregnant women, who pass on immunity to the fetus, Gordon said.
Until the approval this summer of the new monoclonal antibody, nirsevimab, there wasn’t a reliable method to prevent infection in most healthy infants, “nor is there any treatment other than giving oxygen or supportive care,” said Stanley Spinner, chief medical officer and vice president of Texas Children’s Pediatrics and Texas Children’s Urgent Care.
As with any virus, washing hands frequently and keeping infants and children away from sick people are the best defenses, Duchon said. This approach isn’t foolproof because viruses can run rampant in daycare centers, schools and parents’ workplaces, she added.
Mickayla Wininger, Malcolm’s mother, insists that family and friends wear masks, wash their hands and use hand sanitizer when they’re around her daughter and two sons. She doesn’t allow them to kiss or touch the children. Some people take it personally, but she would rather be safe than sorry.
Wininger recalls the severe anxiety caused by Malcolm's ordeal with RSV. After returning with her infant from his hospital stays, she was terrified to go to sleep. “My fiancé and I would trade shifts, so that someone was watching over our son 24 hours a day,” she said. “I was doing a night shift, so I would take caffeine pills to try and keep myself awake and would end up crashing early hours in the morning and wake up frantically thinking something happened to my son.”
Two years later, her anxiety has become more manageable, and Malcolm is doing well. “He is thriving now,” Wininger said. He recently had his second birthday and "is just the spunkiest boy you will ever meet. He looked death straight in the eyes and fought to be here today.”