Children often suffer from colds at least 6-7 times a year. In their first year of preschool, children experience illness at a rate over 50% higher than those cared for at home.
The common cold is an illness caused by viruses, presenting symptoms such as a runny nose, nasal congestion, along with systemic symptoms and other signs like muscle pain and fever, which may be absent or mild. The illness is often referred to as rhinitis; however, it also involves the mucous membranes of the sinuses, thus it is also called rhinosinusitis. The most common infectious agent is rhinovirus, but many other types of viruses can also cause colds.
Colds are more common in cold seasons
Colds occur year-round, but the highest incidence is from early autumn to late spring, reflecting seasonal viral infections associated with the clinical presentation of colds. The peak incidence of colds occurs in early autumn (August to October) and in late spring (April to May). The seasonal prevalence of parainfluenza virus is generally highest in late autumn, while infections from respiratory syncytial virus (RSV) and influenza virus peak from December to April.
Children typically catch colds 6-7 times a year, with about 10-15% of children experiencing colds more than 12 times annually. The frequency of colds decreases with age; adults typically catch colds 2-3 times a year. In their first year of preschool, children have a 50% higher illness rate compared to those cared for at home. However, the illness rate in groups of children decreases over time as they are cared for in preschools.
Transmission of cold viruses
Cold-causing viruses are often transmitted via small aerosol droplets, larger droplets, or through direct contact. Although the pathogenesis of colds generally follows these transmission mechanisms, each virus has its own specific transmission routes. Studies on rhinovirus and RSV indicate that their main transmission route is through contact, although transmission via larger droplets can occur. In contrast to rhinovirus and RSV, influenza virus typically spreads through small aerosol droplets.
Respiratory viruses have different mechanisms of pathogenesis to evade the host’s immune defenses. Rhinovirus and adenovirus infections generate specific immunity in the serum. Humans can be reinfected with these viruses due to the existence of many serotypes. Similarly, influenza can mutate its surface antigens, resulting in numerous serotypes. The interaction between coronaviruses and host immune responses is not well understood, but it is likely that different strains of coronaviruses can also induce short-term immunity. In contrast, parainfluenza virus and RSV have fewer serotypes. Reinfections with these viruses occur because immunity against them is often not established after infection. While reinfections are not prevented by the host’s response to the virus, the illness is usually not severe due to prior immunity.
Symptoms of cold virus infection
Clinical symptoms of colds typically appear 1-3 days after virus infection. The first symptom is a sore or scratchy throat, followed by nasal congestion and a runny nose. Sore throat symptoms usually resolve quickly, while nasal congestion and runny nose may worsen on days two and three. Cough occurs in about 30% of cold cases and usually appears after nasal symptoms. Fever and other symptoms of colds are more common with infections caused by influenza viruses, RSV, and adenovirus than with rhinovirus or coronaviruses. Generally, colds last for about a week, with only about 10% of cases extending to two weeks.
The clinical manifestations of colds are typically limited to the upper respiratory tract. Nasal discharge is usually easily noticeable. The color and consistency of nasal discharge can change throughout the course of the illness and do not indicate a diagnosis of sinusitis or upward infection. Examination of the nasal sinuses may reveal symptoms of swelling and congestion, but these findings are not specific for diagnosis.
Symptomatic treatment for colds
Fever: The fever associated with colds usually does not cause complications, and the use of antipyretics is generally not indicated.
Nasal congestion: Adrenergic agents, both oral and topical, can effectively reduce nasal congestion. Topical adrenergic agents such as xylometazoline, oxymetazoline, or phenylephrine are available as drops and sprays. These medications are also produced in lighter formulations (with weaker effects) for use in children, but their use is not approved for children under 2 years old. Oral imidazoline medications (like oxymetazoline and xylometazoline) rarely cause side effects like tachycardia, low blood pressure, and coma. Long-term use of topical adrenergic agents should be avoided as it may lead to rhinitis medicamentosa, causing rebound congestion with continuous use. Oral adrenergic medications are less effective than sprays and can have complications such as central nervous system stimulation, hypertension, and palpitations.
Runny nose: First-generation antihistamines can reduce runny nose symptoms by 25-30%. The effectiveness in reducing runny nose may be more related to their anticholinergic properties rather than their antihistamine effects, which is why second-generation antihistamines (non-drowsy) do not help with cold symptoms. The primary side effect of antihistamines is drowsiness, but there is evidence that this side effect is milder in children than in adults. Runny nose can also be treated with ipratropium bromide, an anticholinergic nasal spray. This medication is similarly effective as antihistamines but does not cause drowsiness. Common side effects of ipratropium include nasal irritation and nosebleeds.
Sore throat: Sore throat symptoms in colds are usually mild, and analgesics are indicated to alleviate symptoms, especially when accompanied by muscle aches and headaches. Acetaminophen in rhinovirus infections may suppress the neutralizing antibody response, though this is not clinically significant. Aspirin should not be given to children with upper respiratory infections due to the risk of Reye’s syndrome.
Cough: Generally, cough treatment is not necessary for children with colds. Cough symptoms in some cold-infected children may result from upper respiratory irritation from nasal discharge. Cough symptoms are more pronounced when nasal symptoms peak, and treatment with first-generation antihistamines can yield good results. Some patients may cough for several days to a week from the onset of illness and may require bronchodilators. Studies using codeine and dextromethorphan hydrobromide have shown no effect on cold-related cough symptoms. Expectorants like guaifenesin are ineffective against cough.
Preventing colds
Overall, preventive measures and immunization against colds are not routinely used. Immunization or antiviral medication against influenza may be effective for colds caused by influenza viruses. Vitamin C and echinacea have been reported to prevent colds; however, detailed research has not confirmed their efficacy in cold prevention.
Colds can be prevented by stopping the spread of the virus through contact. In hospitals, preventing the spread of respiratory viruses is effective by wearing masks (or head and face coverings) to block transmission from hands to eyes and from hands to noses. Preventing virus transmission through direct contact can be effectively achieved by washing hands among those infected or at risk of infection.
