Immune System

If you catch a cold, it means you have a weak immune system

In some circles, catching a cold is a sign of weakness. Only those with a weakened immune system are thought to be susceptible to colds. So if you come down with something, it is considered a sign that something is wrong with your immune system.

This is not true! First of all, researchers have done many studies where they try to infect people with colds. They put various viruses that cause colds (rhinoviruses, respiratory syncytial viruses, coronaviruses, and so on) directly into the nostrils of healthy volunteers, and then they see who gets sick and who does not. Under normal conditions, with a normal mix of volunteers, many of the people who are exposed to a cold-causing virus will get sick. When you have cold viruses right in your nose, 75 to 90 percent of those exposed will get sick. That means that lots of normal, strong people still get sick when they are exposed to a nasty virus. People with certain immune deficiencies or disorders of their immune system are, indeed, even more likely to get sick, but most people who get colds do not have problems with their immune system. In one study where 394 healthy subjects had cold viruses put right into their noses, there was no difference in the immune systems of those who got infected and those who stayed healthy when they measured things like while cell counts and total immunoglobulin levels.

Another important thing to remember is that it is normal to get quite a number of colds. Children, in particular, frequently get colds. It is normal for a child to have six to ten colds a year, and that seems like a great deal to parents and everyone involved, but it is normal. Having that many colds does not mean that there is a problem with the child’s immune system. Adults do not get quite as many colds either; they get two to four colds a year on average. But it is normal for adults to continue to be exposed to new strains of viruses or to new viruses altogether, and we quite commonly get sick from them. Even if our immune systems are perfectly normal.

That study of 394 volunteers exposed to colds did reveal a different, interesting fact about who was more likely to get sick: having more psychological stress was associated with an increased risk of getting a cold. The more psychological stress a volunteer had, the more likely they were to get infected with the cold virus. Other factors that could have explained the connection between stress and getting sick did not explain it away: in this study, smoking, how much alcohol you drank, your exercise, your diet, how well you slept, and the measures of your immune system did not change whether you got infected compared to your psychological stress. Personality did not matter either. Your level of self-esteem, your personal control, and whether you were introverted or extroverted did not change how likely you were to be infected; it was just your level of psychological stress. It is important to note that smoking by itself renders you significantly more susceptible to colds as well. Based on this study, being under psychological stress does not weaken your immune system in the obvious ways; it does not decrease how many white blood cells you have to fight infections or change the levels of antibodies against infections. But, somehow, those under psychological stress did get infected with colds more often.

While a weak immune system is not to blame, there are a number of interesting factors that are associated with being more susceptible to colds. Psychological stress is one, as we have mentioned. Another issue is not sleeping for very long or not having good quality sleep. People who have a more diverse social network, meaning that they have more friends, family, and work connections, are also less likely to develop colds. How these factors work are not exactly known. The studies are not cause-and-effect studies that tell us how these factors could help or hurt our bodies’ susceptibility to colds. Nonetheless, getting enough sleep and trying to decrease stress might be helpful in protecting yourself from colds.