For parents, certain sounds can evoke an almost physical response — crying at 3 in the morning, eerie midday silence, but perhaps most dreaded: the sniffle. The common cold, ear infections and fever are all surefire ways to upend a carefully orchestrated daily routine, and for some, that may happen a little too often.
When it feels like your child is perpetually sick, questions naturally come to mind: Does my child have a weak immune system, are my child’s clothes warm enough, is it best to avoid baths before bed? Nipunie S. Rajapakse, M.D., M.P.H., a pediatric infectious diseases specialist at Mayo Clinic Children’s Center in Rochester, Minnesota, says it’s understandable to be concerned.
Q: In your opinion, how often will most children get sick?
A: It varies a lot among kids. But most babies, toddlers and preschoolers can have as many as 12 colds a year and still be normal. On average, you’ll probably see between seven and eight infections a year. This number may be higher for children who are in child care or when they start school. It’s also typical for kids to have symptoms lasting up to 14 days. And sometimes a cough can last up to six weeks. That means kids can be sick for a majority of the year and still have a pretty typical immune system.
Q: If that’s typical, then what’s not? And at what point would you consider a child to have something more serious going on, such as an immunodeficiency?
A: This is one of the most common questions we get in the office. Our first step is to take a very detailed patient history. Certain red flags push us to think that something outside the ordinary may be going on. If a child ends up in the hospital after every illness, if a child frequently needs IV antibiotics to get better, if a child develops infections in less common body locations, such as the liver or spleen, or with unusual organisms — those make us wonder about the child’s immune system. If a child gets a cold that lasts 1 to 2 weeks, we’re much less concerned about a major underlying immune system problem.
Other red flags:
- Eight or more ear infections within a year
- Two or more serious sinus infections within a year
- Two or more months on antibiotics with little improvement
- Two or more pneumonia infections within a year
- Recurrent deep skin or organ abscesses
- Persistent thrush in the mouth or elsewhere after 1 year of age
- A family history of primary immunodeficiency
Q: Do certain lifestyle factors play into this? Does sending kids to child care mean they’ll get sick more often?
A: Sure. Kids in child care typically have a higher frequency of illness because they are usually in close contact with many other children from other households. If we hear that a child started child care three months ago and has been sick several times since then, we’re less concerned about a compromised immune system. But other factors should be considered too.
Q: What about cold weather? Should I just expect a lot more colds in the winter?
A: The outdoor temperature itself does not influence how frequently you get sick, but some respiratory viruses tend to circulate on a seasonal basis. When it gets cold outside, people move inside where they’re in close contact and viruses spread more easily. For example, in the Northern Hemisphere we usually see influenza virus circulating from late fall to early spring.
Q: How about wet hair or, more specifically, putting a child to bed with wet hair after a bath?
A: That has no impact. These types of illnesses are caused by respiratory viruses. There’s no link between those and having wet hair.
Q: Can a child’s diet impact the immune system?
A: A lot of research has been done on whether nutritional deficiencies increase the frequency of illness. In cases of severe malnutrition, children are usually profoundly immunocompromised. For a child who has access to food and a varied diet, that’s much less likely. Some studies have demonstrated that lower vitamin D levels might be linked to increased frequency of respiratory infections, but it’s not clear whether supplementation reduces the risk.
Q: If my kid eats too many crackers one day, that’s not upsetting their system?
A: No. In a country like the United States, it’s rare to see severe nutritional deficiencies outside of very particular circumstances.
Q: Breastfeeding comes up often when reading about childhood illness, that it could impact a child’s immune system. Could that be a factor?
A: Breastfeeding is one of the great things that can reduce frequency of illness, primarily early on in life. Breast milk contains protective antibodies from the mother that transfer to the baby. Once in the baby’s body, most of those antibodies line the nose, the mouth and the digestive system. They provide some protection against respiratory illnesses and stomach-flu type illnesses.
Q: A lot of us have just come out of isolation because of the pandemic. Parents may be wondering whether all that time cooped up may have lessened their child’s immune response. Any validity to that?
A: No. Your immune system is constantly being generated and maintained by your body, so being inside and avoiding infection isn’t going to inherently cause any weakening of your immune system. What can happen is your protection against certain infections can drop over time if you don’t get the infection or get vaccinated against infections. For example, since we were all isolated last year, the flu season was very mild — almost nobody got the flu last year. So without the flu shot, your antibody levels are lower. Your protection against the flu this year is going to be much lower. What we recommend is that you get your flu vaccine. That’s the best way to boost your protection without having to deal with the downsides of getting flu itself.
Q: Along that same vein: Do you have an opinion on the hygiene hypothesis?
A: That’s a complicated topic, actually. Kids’ immune systems are uniquely designed to identify and respond to new infections and exposures. They’re constantly being exposed to new things. That’s one way the immune system is trained. So certainly, what you’re exposed to earlier on will train your immune system to recognize what’s dangerous and what isn’t. And so yes, there is some basis to that part of the theory, but it’s pretty nuanced. No one is suggesting that kids should go eat sand from the sandbox or anything like that. But at the same time, living in a fully sterilized society probably isn’t good for people’s immune systems either.
Q: Are there some viral infections that are better to get young, like chickenpox? And conversely, are there any viruses that affect kids more than adults?
A: Yes, there are some infections that are worse if you get them early on. Infection with respiratory syncytial virus (RSV) is especially bad for kids under 12 months. Whooping cough (pertussis) is another that can lead to hospitalization in babies and young kids. On the flip side, viruses such as Epstein-Barr virus and cytomegalovirus — viruses that cause mono — may not even cause symptoms in young kids. But if you get them as a teenager or adult, they can knock you out.
Q: Do you think there’s any merit to giving kids antibiotics less often? Would holding off on them impact a child’s broader immune system?
A: As to your first question, we know that many common infections — such as colds, coughs, runny noses and most sore throats — in children are caused by viruses. Antibiotics do not work against viruses. Taking an antibiotic for a viral infection will not help your child recover faster and can even cause harm. Antibiotics work against bacteria, but even some bacterial infections will get better without needing antibiotics. Ninety to ninety-five percent of ear infections usually get better on their own because the immune system fights off the infection. Antibiotics can also have side effects, such as yeast infections or diarrhea or rashes. So, in general, our approach in medicine is to limit the use of antibiotics to situations where we know the benefits of antibiotics clearly outweigh the risks. But as to whether it would impact your immunity, I would say no.
Q: OK, so maybe my kid doesn’t have a weak immune system, but is there anything I can do to boost immunity anyway?
A: For any parents who are concerned about the frequency of their children’s illnesses, the most important thing they can do is talk to their health care providers. The primary care provider can help differentiate whether a child is experiencing something within the usual realm or something that requires further evaluation. Secondly, it’s important to make sure you as the parent are doing everything you can to prevent infection. One of the best ways to do that is to keep your child’s vaccinations up to date. The pneumococcal conjugate vaccine (PCV13), for example, protects kids against 13 different types of Streptococcus pneumoniae bacteria. These bacteria are the most common cause of ear infections, sinus infections, pneumonia and meningitis in children. The flu vaccine and the COVID-19 vaccine when it’s approved for kids are also great. All vaccines are helpful because they train your child’s immune system to recognize these harmful pathogens without experiencing the actual illness.
Nipunie S. Rajapakse, M.D., M.P.H.
Dr. Rajapakse is a pediatric infectious diseases physician at Mayo Clinic in Rochester, Minnesota. Her clinical focus includes management of pediatric infections. Her primary research interests include studying ways of optimizing antibiotic use in children (antimicrobial stewardship) to decrease antibiotic resistance and other harmful effects. She has worked for the World Health Organization and has an interest in global health and outbreaks of emerging infectious diseases.