More than two hundred viruses can give you a cold
The common cold is humanity’s most frequent infection: adults average two or three a year, children six to eight, mostly in winter. Over two hundred viral strains can cause it—especially rhinoviruses, plus coronaviruses and adenoviruses—so no single vaccine can keep up.
A cold is a viral infection of the upper airway, settling in the moist lining of the nose, throat, sinuses and voice box. It tends to open with tiredness, chills, sneezing and a headache, then a runny nose and cough a couple of days later. Symptoms can begin as soon as sixteen hours after exposure, usually peak within two to four days, and fade in a week to ten days. About half of sufferers cough, about half ache, and roughly four in ten get a sore throat. Green or yellow mucus says nothing about whether a virus or a bacterium is to blame.
Rhinoviruses cause up to 40% of colds and come in more than 100 serotypes, alongside coronaviruses, adenoviruses, parainfluenza and RSV. Much of the misery is the immune system's reaction rather than direct viral damage. That variety, plus rapid mutation, is why no vaccine exists.
The viruses travel in droplets released by breathing, talking and coughing, or via hands that touch contaminated surfaces and then the face. Schools and daycare centres are hotspots because children crowd together with little immunity and patchy hygiene, then carry infections home. There is no evidence that recycled cabin air on airliners spreads colds. Animals are an unlikely source: when a British research base on Adelaide Island had an outbreak after seventeen weeks of isolation, investigators suspected a contaminated object or a symptom-free person, not the sled dogs.
Prevention comes down to physical measures: proper hand washing, which helps especially among children, respirators, better indoor air and staying away from the sick. There is no cure. Rest, fluids and warm salt-water gargles are sensible. Ibuprofen can ease aches, short courses of decongestants may help adults a little, and antihistamines give only a day or two of relief with drowsiness as a cost.
Source: Common cold
