By Stephanie Chester, Manager, Influenza Program, APHL
“Oh, it’s just a cold,” seems to be a common phrase heard in office spaces and schools alike during the winter months. But is it just a cold? Are we belittling our coughs and sneezing by grouping them under one tiny umbrella term? While the common cold is, in fact, common it is by no means simple. Your sniffles are never just a cold.
So how common is the cold? The viruses behind the common cold impact all of us at an average of two to three illnesses per year for adults and six to eight illnesses per year for young kids. And despite there being a cold season, these viruses are not actually confined to the winter months. There are differing theories on why people seem to catch colds more frequently during the winter but most agree that the viruses transmit more readily when people are clustered together in schools and offices. “Environmental conditions may be a factor in which cold viruses are circulating,” said Kirsten St. George, MAppSc, PhD, chief of viral diseases at The Wadsworth Center, the New York State Department of Health’s public health laboratory . “It is not well understood, but certain viruses seem more stable in specific temperature and humidity conditions.”
There are more than two hundred viruses behind the common cold, and there may be many more still that have not been identified. Rhinoviruses are the traditional cause of the common cold, but there are at least 100 rhinovirus serotypes (distinct variations of the virus). A close relative of rhinoviruses are the enteroviruses which you probably heard about with the fall 2014 enterovirus D68 outbreaks; in a normal year they typically cause mild respiratory illness. Other cold causing viruses include human parainfluenza viruses and human metapneumoviruses.
There is a veritable alphabet soup of virus names – but why does the specific virus matter to us if they all just cause a cold?
As you can probably imagine, the fact that there are hundreds of cold-causing viruses, each with several different strains and serotypes, creates many challenges for scientists, healthcare providers and public health practitioners. For starters, it makes it nearly impossible to predict which viruses will be dominant in a given season. “There may be a swell of dominance for one virus, but then it will fade and another will take its place,” explained Dr. St. George.
So if we can’t predict it, why don’t we just prevent it? Why is there not a vaccine for the common cold much like there is for influenza? Again, the sheer volume of viruses and their ability to change and evolve over time is a huge hindrance to this process. To create an effective flu vaccine, said Dr. St. George, researchers must change the vaccine composition annually, or nearly annually, to keep pace with the variants of the virus in circulation. In contrast, she said, “With the cold, there are a myriad of types within a single group, dozens of types circulating all of the time.” This diversity would make the creation of a vaccine very expensive and difficult. It is more likely that researchers will focus on ways to stimulate the immune system to respond more productively to infection and on medications to relieve symptoms.
One area where science is making progress is in the diagnostics and surveillance of the common cold and other respiratory viruses with the advent of new molecular tests. “A lot of these viruses were difficult to identify with classical virology laboratory methods such as culture,” said Dr. St. George. “They just don’t always grow well – or at all – in culture. With new technology, especially the commercially available molecular kits, they are readily detectable.” This advance may not save us from the coughing and congestion, but it provides researchers, physicians and public health practitioners with improved data about what is circulating and causing severe illness. And that information has a multitude of benefits!
For starters, data from these tests may ultimately help researchers and physicians learn if certain demographics or risk factors increase a person’s chance of more severe illness. This may allow for prevention and mitigation strategies, or may lead to a physician being more aggressive with treatment and supportive therapy. Though, as Dr. St. George explained, serious reactions are not limited to those higher risk populations such as those with underlying health conditions. “We have seen very severe manifestations in otherwise healthy people who ended up in intensive care.” Even still, understanding if it is the virus or the host that predisposes a person to more severe illness is incredibly helpful.
Additionally, school officials may decide to cancel classes (or not) if they know the current outbreak of sniffles and coughs is caused by a more troublesome virus. Hospitals can use this data to cluster and isolate patients when needed so respiratory outbreaks don’t spread throughout the entire facility.
While understanding the different viruses that cause the common cold is valuable to public health, we also keep a close eye on how cold treatment may be contributing to a larger health concern: antibiotic resistance. Antibiotics are overprescribed for many things including the common cold. Cold viruses do not respond to antibiotics because they are viruses; antibiotics are only effective for bacterial infections. “Often the thought process is that when you get sick, you should go to the doctor, get some antibiotics and get better,” said Lisa McHugh, MPH, influenza surveillance coordinator and supervisor for the regional epidemiology program at the New Jersey Department of Health. “There is not a clear understanding [among the public] of the difference between bacteriology and virology, and what the standard treatments are for each.” She went on to emphasize that it is critical for the public to understand the difference and that antibiotics are not be the remedy for every ailment. Dr. St. George agreed. “Clinical judgment is important. People need to trust their doctors. They are pretty good at telling when your illness is viral. We are in a time where we need to look carefully at antibiotic use and keep them in reserve.”
Next time you hear someone say, “Oh, it’s just a cold,” you can let them know they may actually be sick from one of hundreds of viruses. Regardless of which one (or several) has struck your family this year, remember to cover your coughs and sneezes with your elbow, wash your hands and stay home when necessary to prevent sharing your virus with others. While scientists work to broaden their understanding of this complex group of viruses, we can help make the common cold a little less common.