(CNN) It's that time of year when nobody, especially children, seems to stay healthy.
Of course, nobody likes to be sick, and there's no question that children should be vaccinated and spared scourges such as measles, whooping cough and diphtheria. For common diseases for which there are no vaccines, such as strep throat, parents should try to protect their children from exposure by keeping them away from infected individuals.
But are there some diseases that might actually be good for children to get? Viruses or bacteria that cause only mild infection in young people, but give them immunity from the same or more serious infections later in life?
The answer is yes, but the list is short. The common cold and ear infections may be among the not so bad -- and possibly even good -- illnesses.
"It's not good for children to get most infections," said Neal Halsey, pediatrician and professor in the Johns Hopkins University School of Medicine and Bloomberg School of Public Health. "But we do understand that trying to protect them from all infections is not necessarily beneficial to the child, because there is some pretty good evidence now that the hygiene hypothesis is correct."
This hypothesis posits that children who grow up without exposure to common bacteria and viruses in the environment could be more likely to develop allergies and autoimmune diseases.
However, experts argue that even bugs that cause seemingly harmless infection are not always so benign.
"I've seen children develop devastating and even fatal disease from (cold and ear infections)," said Dr. Mark R. Schleiss, professor of pediatric infectious diseases and immunology at the University of Minnesota Medical School.
"In all cases, it would be better to have a vaccine, and (the cold, ear infections, fifth disease) all have vaccines in research and development."
In the end, parents should try to protect their children from diseases, because in almost every case (except perhaps the cold), prevention is possible, even if there is no vaccine yet. But if your child gets sick, despite your best efforts, there could be some upsides.
Nobody likes the runny nose, sneezing, fever and cough that come with the cold. Preschool-age children and kindergartners get about nine to 12 colds a year, respectively, compared with teens and adults, who get about seven. "You don't want to try to protect your child against every common cold because you can't," Halsey said.
On the bright side, the recurring sniffles that inevitably plague young children do help prevent sickness when they are older. We develop immunity against the cold virus when we are infected and that keeps us from getting sick with the same virus again, at least for a few years.
Sadly, though, we will probably never be totally immune to the common cold. There are about 200 different strains of viruses -- many of which are a type of rhinovirus or adenovirus -- that cause the cold. So while we may get fewer colds as we age, there are probably still some out there that can get us.
Day care can be a breeding ground for ear infections. Research suggests the onslaught of ear infections hits children when they are in a large group setting for the first time, whether it is in day care or later, when they go to kindergarten. Experts have argued it is better for children to get these infections over with early, before they are further along in school and need to be present to learn to read or take on other important subjects.
"The vast majority of kids get some ear infections, some get multiple infections ... but you want to reduce the risk," because they can cause temporary hearing problems, Halsey said. Bacteria, such as pneumococcus, cause most ear infections, so experts recommend the pneumococcal vaccine as well as the flu vaccine. (The flu virus can spread into the ear.) But if a child gets an ear infection, parents and pediatricians should monitor them rather than rush to treat with antibiotics. Many infections can clear up on their own, and antibiotics can have side effects, such as disrupting the good bacteria of the gut, Halsey said.
Although it is better to prevent ear infections in the first place, having one may help prevent pneumonia down the road. The pneumococcal vaccine protects against 13 types of pneumococcus, but there are 80 others out there. If the infection is caused by one of those, it could help the child develop additional immunity and possibly protect them against pneumonia, said Dr. Margaret K. Hostetter, professor and chair of pediatrics at Cincinnati Children's Hospital Medical Center.
Fifth disease usually causes no more harm than a fever and mild rash in children and adults. About 20% of people who get infected with parvovirus B19, the virus responsible for fifth disease, do not even develop symptoms. However if there is fallout from infection, it tends to be more serious in adults.
Fifth disease gets its name because it is one of five childhood viral infections associated with rash. Whereas children are more likely to develop a rash on their faces and bodies, adults can develop more serious, flu-like symptoms and women are especially at risk of having joint pain and swelling. Although the joint problems typically go away in less than a month, they become chronic in about 10% of adults.
Fortunately, people infected with fifth disease develop immunity that is usually lifelong.
There is a misconception that it's good to expose children to chickenpox, such as by sending them to chickenpox parties, to keep them from getting sick as adults.
"That made sense before we had a vaccine ... but it is so much better to induce that immunity (with a vaccine) without going through the risk of infection and complications of the disease, " Halsey said. "That's the magic of vaccines."
Possible complications of chickenpox infection in children include skin infections, pneumonia and encephalitis, which is inflammation of the brain that can cause fatigue, weakness and even paralysis.
The Centers for Disease Control and Prevention does not recommend the chickenpox vaccine for children younger than 12 months, so parents should do everything they can to avoid exposing babies to the virus, Halsey said. Babies who get infected have a higher risk of developing painful shingles during childhood.