How did we manage to deal with COVID-19 so quickly, but the common cold still remains a persisting problem?

A week or two of cold and cough can make you conjure up some pretty odd conspiracy theories. The freshest one that I cooked up this week is that 'Big Tissue' wishes to keep everyone sick, and therefore they collaborate with 'The Scientists' to keep them from making a cure.

After all, the world witnessed researchers demonstrate incredible and hasty success in combating COVID-19, and yet, the common cold remains an seemingly elusive target. But far from being an actual conspiracy, there are several real reasons why we haven’t yet cracked the code to curing the cold, despite decades of research. So grab your tissues, folks, and let's get into them.

Viral diversity

One major hurdle in curing the common cold is the sheer diversity of viruses involved. Over 200 viruses can cause cold symptoms, with rhinoviruses responsible for up to 75% of cases. Rhinoviruses alone consist of more than 160 known strains. This viral diversity makes it extremely difficult to develop a universal vaccine or treatment. Unlike SARS-CoV-2, which has one main spike protein target, cold viruses come in a dizzying array of structures and behaviours, requiring a vast array of medical solutions.

In contrast, when COVID-19 emerged, researchers focused primarily on one virus and one major target — its spike protein. That focus allowed for the rapid development of vaccines using mRNA technology, like those from Pfizer and Moderna. For the common cold, a similar solution isn’t feasible due to the multiple viral families involved.

Mutations and adaptations

Another issue is how quickly cold viruses mutate. Rhinoviruses, for example, are known for their high mutation rates. This rapid evolution allows them to evade the immune system, which is why even if you’ve had a cold before, you're not immune to future infections from different strains.
This rapid mutation is akin to how COVID-19 has evolved into variants, but with cold viruses, it happens on an even greater scale. Scientists fear that if they developed a vaccine, new strains would quickly render it ineffective, much like how seasonal flu vaccines must be reformulated annually.

Mildness of the illness

Ironically, one reason the common cold hasn’t been cured is because it’s too mild to warrant massive investment. Most people recover from a cold without medical intervention. While cold symptoms are annoying — runny nose, sore throat, cough — they rarely escalate into serious illness. As a result, pharmaceutical companies and governments have little financial incentive to pour billions into research for a disease that poses no significant threat to public health.

COVID-19, on the other hand, caused severe illness and death on a global scale, spurring massive investment from both the public and private sectors. Governments and companies alike invested heavily in research and fast-tracked vaccines, which led to solutions much quicker than we’ve seen for colds.

Complex, complex immune system

The immune system’s response to cold viruses is also a significant factor. Studies have shown that repeated exposure to cold viruses over a lifetime results in limited immunity. For instance, research from Harvard points out that even though the body produces antibodies after a cold, the immune response isn't strong enough to prevent future infections from slightly different strains. This is in stark contrast to diseases like measles, where one infection can result in lifelong immunity.

COVID-19 benefitted from its novelty. The immune system had never encountered SARS-CoV-2 before, making it easier to target with vaccines that produce a strong and specific immune response.

Here’s an additional fun fact: because there are SO many different strains of common cold-causing viruses, research says that it is unlikely that you will be infected with the same strain of common cold twice throughout your life!

Attempts to develop treatments

There have been attempts to develop treatments for the common cold. Some researchers have targeted the way viruses enter and replicate in human cells. For example, a 2018 study explored inhibiting the protein that cold viruses use to replicate, showing some promise in early trials. However, most of these treatments are in the experimental phase, and none have been widely successful yet.
In recent years, attention has shifted towards using broad-spectrum antiviral drugs that can target multiple viruses at once, similar to how some antibiotics work against a range of bacteria. However, this approach has yet to yield a major breakthrough.

The idea of a universal cure for the common cold remains distant, but advances in genetic research and vaccine technology offer some hope. For example, CRISPR technology may allow scientists to edit out the genetic components that cold viruses rely on to replicate. Additionally, the mRNA technology used for COVID-19 vaccines has opened new possibilities for antiviral treatments, although these applications are still in early stages.

Research continues, but for now, humanity may have to continue battling sniffles and coughs the old-fashioned way: with rest, fluids, and time.