Why we can’t squash the common cold, even after 100 years of studying it

Before germs were first spied under a microscope by Robert Koch, a doctor from East Prussia, catching colds was blamed on evil spirits, foul weather, and medical enigmas such as blood impurities. Koch’s findings ignited the medical community in the late 19th century. Many of humanity’s dreaded afflictions soon had microbial faces of a sort and, more importantly, specific organisms for doctors and scientists to study: The cause of  tuberculosis was identified in 1882, cholera in 1883, salmonella and diphtheria in 1884, pneumonia in 1886, and tetanus in 1889. In 1883, Popular Science was among the first publications to forward and promote the emerging and controversial germ theory of disease. Even as some in the medical community resisted mounting evidence for germ theory, the 1880s became known as the golden age of bacteriology. In that same decade, Louis Pasteur, a French chemist, developed the first human vaccine, which successfully prevented rabies in a single-person trial. 

But folklore is stubborn, capable of resisting even the most compelling facts. By 1925, when Popular Science reported the findings of the US Public Health Service’s first-ever survey on the common cold, many still clung to outdated beliefs despite four decades of germ science.

As contributing writer Malcolm MacDonald noted, the myth persisted that colds were typically caused by “bad weather or wet feet.” MacDonald pressed the case for germs as the root cause of the common cold, even though no specific pathogen had yet been identified in 1925. “The common cold, at least some varieties, is extremely contagious,” MacDonald wrote. “Prevention lies in avoiding contact with sufferers.” We’ve learned much about the common cold since 1925—from its underlying viruses to its seasonality. But we still contract it just as frequently as we did a century ago; we still suffer the same symptoms for the same duration; and there’s still no vaccine. In other words, “avoiding contact with sufferers” remains the best prevention even after a hundred years.

It wasn’t until the 1950s that the common cold’s elusive origins began to surface. Inspired by the success of Jonas Salk’s polio vaccine, some researchers set their sights on curing the common cold. But, as Popular Science reported in November 1955, scientists were playing catch-up. It wasn’t clear which viruses caused the common cold, or how many there might be. Robert Huebner, a US Public Health Service virologist, had identified adenovirus in 1953 as a contributor, but it soon became clear that adenovirus was not the only one. By 1956, Winston Price, a Johns Hopkins University virologist, had discovered rhinovirus as another cause. Since then, three species of rhinovirus have been identified (A, B, and C).

The more scientists dug into the common cold, the more they learned that what we thought of as the common cold was just a catch-all for similar upper respiratory symptoms caused by several different viruses, amounting to hundreds of different strains. While rhinoviruses account for as much as 30–50 percent of common cold cases, and non-Covid coronaviruses another 10–15 percent, other causes include adenoviruses, respiratory syncytial viruses (RSV), and parainfluenza (non-flu) viruses. 

Although there are more than a billion cases of the common cold in the US each year—two to four cases on average for each adult, more for children—there has been little progress on a vaccine because of the sheer number of viral strains such a vaccine would need to target. Fortunately, an RSV vaccine is now available for vulnerable populations like infants and the elderly. But RSV only accounts for a fraction of common cold cases. Even a rhinovirus vaccine, which would require more than 100 strains in one dose, would not prevent a majority of cases. 

While a universal common cold vaccine remains elusive, many of MacDonald’s century-old observations about prevention, treatment, and seasonality have stood the test of time. They remain uncannily accurate considering the root cause of the common cold had not yet been identified in 1925. For instance, MacDonald went to great lengths to explain how stifling indoor conditions during the winter months could make us susceptible to colds, writing: “This hot dry air is very irritating to the nerves and injurious to the eyes. It makes the membranes of the nose and throat too dry, which is harmful.” MacDonald was onto something. We now know that while weather is not a direct cause of colds, our environment matters. Dry air—hot or cold—can reduce mucosal defenses, making people more susceptible to infections. We also know that common cold viruses are highly contagious and spread more easily indoors than outdoors through airborne droplets, direct contact, and contaminated surfaces. Fortunately, 21st-century indoor environments tend to be a bit more sanitary than in MacDonald’s day, with improved ventilation systems and air purifiers.

MacDonald also cited the US Public Health Service’s observation about the seasonality of common colds, with the largest peak in October and another smaller peak in January. Similar peaks still exist, especially in northern regions, although they move around a bit. In 1925, just like today, seasonal peaks often coincide with the start of the school year (October or autumn peak) and holiday gatherings (January), when people tend to gather indoors.

MacDonald identified certain risk factors for catching colds, such as being overfed, under-exercised, and constipated. However, in the 21st century, we understand that these factors only pose a risk if they lead to psychological stress, which can lower immune response. Other risk factors include lack of sleep, age, smoking, autoimmune disorders, and other diseases.

For treating a common cold, MacDonald recommended a hot full-tub bath at the onset of symptoms followed by rest in a well-ventilated room and a diet rich in fruits and vegetables. Following these measures, the average length of disability for respiratory disorders was less than 6 ½ days. Today, the advice for treating a cold remains similar, including rest, hydration, healthy eating, and using indoor vaporizers. While we now have decongestants and pain relievers, there is still no cure, and the duration of a cold remains several days to a couple of weeks.

MacDonald’s article underscores the early scientific approach of the 1925 US Public Health Service survey in understanding common colds through population-level data. Building on this science over a century has equipped us with knowledge on the causes, prevention, treatment, and risk factors for colds. Despite advancements, the best advice in 2025 remains much the same as in 1925: avoid contact with infected individuals, rest, and maintain healthy habits. While a universal vaccine may not yet exist, adhering to scientific guidance may bring us closer to that goal before the next centennial of MacDonald’s groundbreaking article. Please rewrite the sentence for me.