Its all too common: A toddler starts attending day care or preschool and suddenly it seems like they always have a runny nose, a cough or worse.

Experts estimate that children contract six to eight upper respiratory infections on average each year. As a parent, you may feel helpless in what seems like an endless cycle.

Fortunately knowledge is power. Below, pediatricians explain why little kids tend to get sick frequently after starting day care or preschool, what parents should know about this phenomenon, and how they can help.

Why does this happen?

These days, parents of toddlers are not used to having a sick child, said Dr. Dyan Hes , medical director at Gramercy Pediatrics in New York City. This is because many of their babies were born during a pandemic and these children have essentially spent their lives in a bubble.

She noted that lockdowns, social distancing and masks have decreased childrens exposure to common pathogens over the past two years. And even before the pandemic, toddlers often didnt come into contact with many of these pathogens until starting day care or preschool.

Pre-pandemic, I would reassure parents that children get sick when they start day care because they are exposed to many forms of the common cold and other childhood illnesses, Hes said. Now, two years into the pandemic, I would multiple this by 100! This does not mean that a toddler getting sick is dangerous. It may just happen all at once instead of gradually.

Preschool and day care generally involve groups of children in rooms together, so its inevitable that they will spread contagious illnesses to each other.

Many children will bring viruses with them to preschool and share them with others as they play and explore together, said Dr. Benjamin Levinson , a primary care physician at Nationwide Childrens Hospital. Children with minimal symptoms, which may seem like allergies, can still spread the virus they carry to others. Thus, it is very common for children to get several viral illnesses shortly after beginning preschool as they will be exposed to many viral strains for the first time.

Can parents prevent it?

Really, the only way you can prevent getting a virus or other illness is not to be near someone else with a virus, and thats very difficult if youre going to attend any kind of school, said Dr. Arthur Lavin , a pediatrician at Akron Childrens Hospital. Hand-washing can help slow the spread of viruses like the stomach flu, but for viruses like the common cold that are spread through the air, it can be very difficult.

Lavin recommends teaching your child to wash their hands before eating and after using the bathroom in order to slow the transmission of viruses or infections that spread via touch.

If we really wanted to stop people from getting colds or other sicknesses, wed have to be in a permanent lockdown, Lavin added. When we were in lockdown, that was the first time in recorded history we had no flu epidemic. While that was amazing, no one is willing to live like that, and I wouldnt recommend it.