A global push is in the development of a vaccine to slow the spread of Covid-19, and experts hope several will be ready by 2021. Yet even with one, the coronavirus is likely to stay with us for years and take a long effort to find a cure for those who are still getting sick.
In the millennia-long struggle of mankind against viruses, prevention with vaccines was far more successful than treatment with drugs. In fact, modern medicine has found a real cure for just 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 apparent simplicity of our viral enemies.
“You cannot live alone, you are not independent, you cannot process food, you cannot take in oxygen and you cannot reproduce without the master support system to be the parasite in a living cell,” said Paula Cannon, professor the University of Southern California’s Keck School of Medicine.
Why do viruses cause so much trouble to people? Outside the body, intensive hand washing is enough to kill many. Inside, the immune system’s long memory is enough to get most of them done.
When we come across a new virus, the problems begin.
The SARS-CoV-2 coronavirus is the latest in a procession of new infectious diseases that have surprised the world in recent years. The best hope, however, is a vaccine that can stop infections before they take hold.
A vaccine is essentially an acronym for immunity. But when we don’t have immunity and we get sick, things get more complicated. Since viruses cannot survive on their own, they hijack our cells in order to multiply. This parasitic addiction makes it difficult to treat with most traditional medications. A virus is so interwoven with its host that it is difficult to hurt one without hurting the other. SARS-CoV-2 infects the airways and lungs – exactly the things we need to breathe.
That leaves an unattractive choice, according to Cannon. “I can kill the virus, but I’d have to kill you to do it.”
Some vaccines, such as measles, have created sufficient herd immunity that the virus can no longer establish itself in the population. At best, like smallpox, the shots have driven the disease out of the human host population and are threatened with extinction.
Treating an active infection is a different matter. There is a pharmaceutical cure for only one virus: hepatitis C. Because of the “kill virus, kill host” problem, slowing the virus down enough for the body’s defenses to do its job is often the best option.
“If we can’t kill a virus, the best thing we can do is to stop it from replicating,” said Raed Dweik, chairman of the Respiratory Institute at Cleveland Clinic, Ohio. “We can only shorten the duration of the infection and not cure it. Even when the infection is over, the patient is more cured than cured.”
Remdesivir, the only widely used drug that targets SARS-CoV-2 itself, has a negative effect on the virus’ ability to replicate. It causes errors when the virus tries to copy itself. It was also a lucky product: the drug was originally designed to treat Ebola but wasn’t particularly effective, and the declining outbreak in Africa made it difficult for its maker, Gilead Sciences Inc., to conduct studies.
Clinical studies have shown that remdesivir can help Covid-19 patients recover faster in the hospital. But it is not a cure, and it is unlikely to be any soon.
“It will take years to have effective and specific drugs that can stop the coronavirus,” Cannon said. “The vast majority of drug candidates fail.”
In the future, patients are likely to be given a cocktail of therapies that attack the virus and others to help keep them stable. Currently, remdesivir is part of a cocoon of care that includes the only other approved therapy, the steroid dexamethasone, as well as standard tariffs such as fluids, as well as aggressive approaches when needed, including putting patients on ventilators. Other drugs are superimposed: blood thinners and experimental approaches to calming a potentially overactive immune system.
As new approaches hit the market, they are added to the mix. For most people, however, any virus treatment must surpass an already impressive and established approach: the human immune system.
The best defense
It’s no coincidence that many infections last around two weeks, Cannon said. This is how long it takes for the immune system to shift into gear.
“Our immune system is the world‘s best drug maker,” she said. “Whether you had measles as a 5-year-old or Covid as a 50-year-old, our immune system encompasses this extensive library of potential antiviral approaches that offer protection.”
Antibodies, the infection-fighting proteins made to ward off foreign invaders, are biological drugs that we make ourselves, Cannon said. The body has the ability to produce millions and millions of them and activate just the right thing when it binds to a virus – and then mass-produce it over a period of about 14 days.
“This is when the immune system gets the upper hand,” Cannon said. “There are so many antibodies in the blood coating the virus. They neutralize the virus well. After all, the antibodies win the day.”
These antibodies never completely go back to their initial low levels. Instead, they remain in reserve and on patrol for years in case the threat returns. In this case the answer does not take 14 days.
“When you get the same virus, the infection doesn’t clear up because the antibodies turn on,” Canon said. “You don’t even get sick. Therefore, with the vast majority of viruses, you get them once and are immune in the future.”
It is this process that vaccines mimick. The man-made vaccinations offer the immune system some of the virus and provide just enough for the body to activate against a potential threat without actually making the person sick. The immune system is thus alerted and able to prevent an infection instead of having to fight one off.
This is also the approach behind another wave of therapies being developed for more severe Covid-19 patients. Drug manufacturers have figured out how to raise antibodies that mimic the natural antibodies produced by the body, and experimental drugs based on them have come from Regeneron Pharmaceuticals Inc., Roche Holding AG, and Eli Lilly & Co.
But these therapies are likely reserved for the sickest patients in the hospital. And these types of therapies tend to be expensive – thousands of dollars for a single course. For example, Gilead’s hepatitis C drug cost $ 84,000 after it was approved for sale in the United States in 2013. Biotech drugs like those in development for Covid-19 also cost tens of thousands of dollars per course. Vaccines, on the other hand, tend to be cheap – and keep people away from more expensive treatments.
“Because we can’t treat it very well, prevention is always critical,” said Dweik of the Cleveland Clinic. “Once you are infected, there is little we can do other than help or maybe cut it a little bit. That is why it is so important to find a vaccine.”
Incentives for drug manufacturers
There are hundreds of viruses that cause respiratory infections and are generally grouped under the common cold. Some are coronaviruses. The reason we don’t have treatments for them is because each is so individual, and drug development is so expensive, that it often exceeds $ 1 billion per therapeutic agent. Any treatment would have to be tailor-made for a particular pathogen in a way that is so narrow that it would be almost impossible. Thousands have already failed.
And a cold? It usually goes away on its own.
The broader economy has worked against viral infection drugs in the past, leaving a void in the kind of innovation that has appeared in other, more profitable conditions such as cancer and heart disease. The recent virus outbreaks, including SARS and MERS, both novel coronaviruses and Zika, subsided before new treatments could take hold.
“Think about it from a pharmaceutical company perspective,” said James Cutrell, director of the Infectious Disease Scholarship Program at the University of Texas’ Southwestern Medical Center at Dallas. “Infection is usually an acute illness that you will treat for a short period of time. If it is a rare infection, there might not be that many people taking it. When these other viruses initially came out there was a lot of interest in developing treatments, but once they died out there wasn’t enough for clinical trials. “
Economic incentives for drug makers changed with the Covid-19 pandemic, which is so widespread and disruptive that a vaccine is seen as a societal necessity. As part of its Operation Warp Speed program, the US government has entered into contracts with drug companies to develop and manufacture a number of vaccines valued at approximately $ 10 billion. The recordings they make and their successors could be used around the world for years.
It is certainly not the last new virus the world will encounter either.
“Science tells us that this virus isn’t unique, it’s one of many that circulate in animals that can spread to us,” Dweik said. “There is no reason to believe that this will not happen again.”
(Except for the headline, this story was not edited by GossipMantri staff and published from a syndicated feed.)