If you think your toddler's often ill, you're right—what going to nursery means for catching colds and building immunity

There's no nice way to put it: Small children are snotty. A research study that tested children for multiple respiratory viruses every week for a year found that under-fives are carrying one or more viruses 50% of the time. A child aged 15 months will have 12–15 colds per year and eight or nine of those will show symptoms, such as a runny nose. If parents feel their small children are sick with a cold half the time, that's backed up by evidence.