why do we get colds

The common cold is caused by viral infections, primarily by viruses from the rhinovirus family, which account for about half or more of cold cases. There are over 200 different viruses that can cause colds, including coronaviruses and adenoviruses. The cold virus enters the body through the mouth, eyes, or nose, often spread by droplets from coughing or sneezing, or by touching contaminated surfaces then touching the face. Once the virus infects the upper respiratory tract (nose and throat), the body's immune system reacts, causing symptoms such as runny nose, sore throat, coughing, and sneezing. Symptoms arise mainly as the immune system fights off the virus. People can catch colds several times a year because many different viruses cause colds, and immunity to one does not protect against others. Factors such as genetics, environment, immune system strength, stress, lack of sleep, and poor hygiene can influence susceptibility to colds. Children tend to get colds more frequently because their immune systems are still developing.