Why is treating the common cold so challenging?

Clinical studies for pleconaril, a brand-new drug intended to cure the common cold, were conducted in 2000 by a company by the name of ViroPharma. The medication was helpful for several people. But after only a few days of treatment, scientists discovered altered virus variants in 7 of them that were almost completely resistant to pleconaril. Although viruses are always evolving, this one changed so rapidly that it was able to overcome years of study and development in a matter of days.

Without an immune system, a cold would quickly spread deep inside of your lungs if you had one. There would be constant viral replication destroying tissue to the point where your lungs couldn't oxygenate your body enough and you would suffocate. This is a genuine risk, unfortunately, for the millions of people across the world who have immune systems that aren't completely functioning or who take immunosuppressant medications. "Minor" infections can develop into serious or even fatal conditions. However, if you're fortunate enough to have a healthy immune system, a cold will generally only cause you to experience a few minor symptoms.

Over the course of their lives, adults often contract more than 150 colds. And even while the symptoms are identical, the underlying cause may vary from case to case. At least eight separate virus families, each of which can have its own species and subtypes, are responsible for causing the common cold. There are just a few methods for viruses to enter our bodies, one of which is through breathing. Since we must breathe, our immune system deploys a number of frontline defences, which are actually what cause many of the cold's symptoms. Your immune system traps and flushes away viruses through your mucus-filled, runny nose. Your immune system is raising your body temperature to stave off virus replication when you have a fever. And when you're inflamed, your immune system widens your blood vessels and mobilises its army of white blood cells to fight the virus.

Is there ever a chance of a treatment if the common cold is brought on by so many different viruses? One fact works in our favour: rhinoviruses, which account for 30 to 50% of all colds, belong to a single family of viruses. The common cold would be mostly cured if we could get rid of all rhinovirus infections. Vaccines and antiviral medications are the two main strategies for fighting viruses. A successful, albeit transient, rhinovirus vaccination was originally developed. In 1957, William Price administered an inactivated rhinovirus vaccine to 50 children and a placebo to the remaining 50. A rhinovirus outbreak quickly spread among the children after that. Only 3 people in the vaccination group fell ill. 23 people—nearly 8 times as many—were in the placebo group. The immune systems of children who had received vaccinations were successfully recognising and responding to rhinovirus, which was encouraging despite the tiny numbers. However, further vaccine studies revealed absolutely no protection at all. No one at the time understood that the rhinovirus had many subtypes, therefore this wasn't Price's fault. Price's vaccine, which was only effective against one or possibly a few rhinovirus subtypes—out of 169 variants and counting—didn't offer broad protection for unknown reasons.

When we create a vaccination, we sometimes get luck. For instance, the mRNA COVID vaccinations efficiently shield us from the original virus and its variations as well as serious illness and death. However, we have yet to develop a vaccine that can effectively defend against rhinovirus or any other virus that is responsible for the common cold.

How about antiviral medications? It is challenging to create a chemical that is harmful to the virus without also being dangerous to humans since viruses require the cellular machinery of humans to proliferate and propagate. And even if you are successful, the virus could evolve so that the medication is no longer effective. Viruses are cunning creatures. However, we have achieved some remarkable triumphs, such as the eradication of smallpox due to a potent vaccine, the disease's inability to hide in other species, and the disease's relatively low mutation rate. Contrarily, HIV mutates so swiftly that, in theory,any single-letter mutation in the virus' genetic coding might be created in a single day in an untreated individual.Despite decades of effort, we still lack a vaccine. We do, however, have a potent combination of HIV medications that the virus can't just mutate away from. We are now unable to avoid colds, unfortunately.

However, in the previous few decades, there have been some completely game-changing medical advancements, such as mRNA vaccines and CRISPR. Due to its origins as an immune system defense against viruses in bacteria, CRISPR has great promise as an antiviral agent. A study team even demonstrated that a CRISPR technology could destroy coronavirus and influenza genomes in our lung cells early in the COVID-19 pandemic. Prophylactic antiviral CRISPR in human cells is the name of their mechanism. or PAC-MAN for short.