StemCell Therapy

A global push is on to develop a vaccine to slow the spread of COVID-19, and experts hope several will be ready in 2021. Yet even with one, the coronavirus is likely to remain with us for years, demanding long efforts to find a cure for those who still fall sick.

In humanity's millennia-long struggle against viruses, prevention with vaccines has been far more successful than treatment with drugs. In fact, modern medicine has come up with a true cure for only one viral infection. For many serious infections, the best approaches are a cocktail of drugs that throw speed bumps in front of the infection.

It's a lackluster medical armory, belied by the seeming simplicity of our viral foes.

"They can't live by themselves, they aren't independent, they can't process food, take in oxygen, reproduce themselves without the master support system of being the parasite inside a living cell," said Paula Cannon, a professor at the University of Southern California's Keck School of Medicine.

So why do viruses give humans so much trouble? Outside of the body, a vigorous hand-washing is enough to kill many. Inside, the immune system's long memory is enough to make short work of most.

It's when we run into a new virus that the problems start.

The coronavirus, SARS-CoV-2, is the latest in a procession of new infectious diseases that have surprised the world in recent years. The best hope against it is a vaccine, which can stop infections before they take hold.

A vaccine is, essentially, a shortcut to immunity. But if we don't have immunity and get sick, things get more complicated. Because viruses can't survive on their own, they hijack our cells to multiply. That parasitic dependence makes them hard to treat with most traditional drugs. A virus is so interwoven with its host that it's difficult to hurt one without hurting the other. SARS-CoV-2 infects the airways and lungs the very things we need to breathe.

That leaves an unappealing choice, according to Cannon. "I can kill the virus, but I would have to kill you to do it."

Some vaccines, such as for measles, have created enough herd immunity that the virus can no longer take hold and spread in the population. In the best case, as with smallpox, the shots have driven the disease out of the human host population and into extinction.

Treating an active infection is another matter. There's a pharmaceutical cure for only one virus: hepatitis C. Because of the "kill the virus, kill the host" problem, the best bet is often to slow the virus down enough that the body's own defenses can do their job.

"When we can't kill a virus, the best thing we can do is stop them from replicating," said Raed Dweik, chair of the Cleveland Clinic's Respiratory Institute. "All we can do is shorten the period of infection, not cure. Even when the infection is over, the patient is more recovered than cured."

Remdesivir, the only drug in wide use that targets SARS-CoV-2 itself, works by messing with the virus's ability to replicate. It causes errors when the virus tries to copy itself. It was also a product of luck: The drug was originally developed as a treatment for Ebola, but it wasn't terribly effective and the waning outbreak in Africa made it difficult for its manufacturer, Gilead Sciences Inc., to study.

Clinical trials have shown that remdesivir can help hospitalized COVID-19 patients recover more quickly. But it's not a cure, and it's unlikely there will be one anytime soon.

"It will take years to have potent and specific drugs that can stop coronavirus in its tracks," Cannon said. "The vast majority of drug candidates fail."

In the future, patients will likely get a cocktail of therapies that attack the virus and others that help keep them stable. Currently, remdesivir is part of a cocoon of care that includes the only other cleared therapy, the steroid dexamethasone, as well as standard fare like fluids, plus aggressive approaches when needed, including putting patients on ventilators. Other medicines are layered on top: blood thinners and experimental approaches to calm a potentially overactive immune system.

As new approaches reach the market, they'll be added to the mix. But for most people, any viral treatment will have to outperform an already formidable and existing approach: the human immune system.

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When will there be a COVID-19 cure? Your body is still the best virus-killer - Crain's Cleveland Business

This entry was posted on September 15, 2020 at 10:56 am and is filed under Immune System. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed. |