For parents, there are certain sounds that can evoke an almost physical response — crying at 3 a.m. or eerie midday silence. But perhaps the most dreaded sound: 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? Should my child avoid baths before bed? Nipunie S. Rajapakse, M.D., M.P.H., a pediatric infectious diseases specialist at the 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 attending day care or when they start attending school. It’s also normal 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 normal immune system.
Q: If that’s normal, then what’s abnormal? And at what point would you consider a child has something more serious going on, such as an immunodeficiency?
A: This is one of the most common questions pediatricians get in the office, and the first step in answering that question is to take a very detailed patient history. There are certain red flags that will push us to think there may be something outside of the ordinary going on. Doctors start to wonder about problems with a child’s immune system if a child ends up in the hospital every time they’re sick, if they frequently need IV antibiotics to get better, if they develop infections in less common body locations — such as the liver or spleen — or with have infections with unusual organisms. If a child has chronic diarrhea or is getting sick so often that it is impacting their growth — that can be another clue of a bigger problem. If a child just gets frequent colds that last 1 to 2 weeks, that’s much less concerning for 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 my kid to day care mean that my child will get sick more often?
A: Sure. Kids in day care or a group child care setting will typically have a higher frequency of illness, especially in the first year or two of attendance. That’s because they are in close contact with many other children from other households and are therefore exposed to more variety of viruses and bacteria. If a child started day care three months ago and they’ve been sick several times since then, there’s less concern about a compromised immune system. But there are other factors that should be considered too.
Q: What about cold weather? Should parents just expect a lot more colds with their kids in the winter?
A: The temperature outside does not influence how frequently you get sick, but some respiratory viruses tend to circulate on a seasonal basis. Also, when the weather gets cold outside, people tend to spend more time inside where they’re in closer contact with others and viruses can spread more easily. For example, in the Northern Hemisphere, the influenza virus is usually 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, and there’s no link between those and going to bed with wet hair. That is a myth that has now been debunked.
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 infection, but it’s not clear whether supplementation reduces the risk.
Q: So, if my kid eats too many crackers one day, that’s not upsetting their system?
A: No. In the United States and similarly developed countries, it’s rare to see nutritional deficiencies severe enough to have a major impact on the immune system outside of some very rare circumstances.
Q: Breastfeeding comes up often when reading about childhood illness and its impact on 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 that the mother transfers to the baby. Most of those antibodies line the nose, the mouth and the digestive system, and they provide the baby with some additional protection against primarily respiratory illnesses and stomach flu-type illnesses.
Q: Because of relatively recent isolation during 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 decrease over time if you don’t get “boosted” by being exposed to the infection or getting vaccinated. For example, when people were all isolated and masking during the COVID-19 pandemic, there were very mild flu seasons — almost nobody got the flu. So without the flu shot, your antibody protection against the flu coming out of COVID-19 was likely much lower. What infectious disease experts recommend — and recommend every fall — is that you get your flu vaccine. That’s the best way to boost your protection without having to deal with the downsides and complications of getting infected with the flu virus.
Once most people dropped the COVID-19 preventive measures, which also prevented spread of many other types of infections, kids did begin to get sick more frequently. However, this was expected due to the combination of waning immunity and increased exposure to — and increased circulation of — a variety of viruses. In addition to the removal of COVID-19 preventive measures. It’s not due to anything intrinsically wrong with anyone’s immune system.
Q: Along that same vein: Do you have an opinion on the hygiene hypothesis?
A: That’s a complicated topic that scientists are still trying to fully understand. Kids’ immune systems are uniquely designed to identify and respond to new infections and exposures, and 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 actually pretty nuanced. No one is suggesting kids should go eat handfuls of sand from the sandbox or anything like that. But at the same time, living in a fully sterilized environment probably isn’t good for immune systems either. I think there is still a lot needed to study and understand here.
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: Thankfully, we have a very effective vaccination against chickenpox that is routinely given in early childhood now. Prior to that, getting chickenpox as an adult was associated with more-severe illness and a higher risk of complications than in children.
Beyond chickenpox, there are some infections that can be worse if you get them at certain ages. Respiratory syncytial virus (RSV) is especially bad for kids under 12 months old, as they are more likely to require hospitalization for the infection. In comparison, older children or adults will likely just develop mild cold symptoms if they get infected. Pertussis — or whooping cough — is another infection that can lead to more complications and hospitalization in babies and young kids, especially those under 6 months of age. This is one of the reasons certain vaccinations, such as for pertussis, are recommended at specific ages: to protect children when they are most vulnerable to these infections and their complications.
Additionally, vaccinating those who are pregnant in the second or third trimester has been shown to provide great protection for newborns, especially during the first few months of life before they have completed their own vaccination series. This has been demonstrated nicely for influenza, COVID-19, and pertussis and more recently for RSV, which is very exciting.
On the flip side, there are some viruses like Epstein-Barr virus or cytomegalovirus — or viruses that cause mono — that may not even cause symptoms in young kids. However, if you get them as a teenager or adult, they can really knock you out. COVID-19 is another example where older adults tend to be at higher risk of getting sicker and winding up in the hospital or with complications, than do children.
Lastly, there are also infections, such as influenza, that can cause more-severe illness and complications at both extremes of age — both in young children and in older adults. That’s why it’s recommended that anyone over 6 months of age get an influenza vaccine every flu season.
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, it’s known that antibiotics continue to be overprescribed for many common infections — such as colds, coughs, runny noses and most sore throats — which 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 only work against bacteria, but even many bacterial infections like ear infections and sinusitis will get better without an antibiotic. About 90% to 95% of ear infections will usually get better on their own because the child’s immune system will fight off infections even if caused by bacteria.
Antibiotics also can cause side effects, things like yeast infections or diarrhea or rashes, which can sometimes be even worse than the infection you are trying to treat. Taking antibiotics frequently also increases your risk of developing future infections with bacteria that are resistant to antibiotics. That’s why, in general, the approach in medicine is to limit the use of antibiotics to situations where the benefits of antibiotics clearly outweigh the risks. Antibiotics are definitely required and can be lifesaving in the treatment of certain infections. It’s important to preserve their effectiveness for those situations. It’s also important to discuss with your healthcare professional whether an antibiotic is needed or not. 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 parents who are concerned about the frequency of their child’s illnesses, the most important thing they can do is talk to their healthcare professional. They can help differentiate whether a child is experiencing something within the normal 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 routine vaccines up to date. The pneumococcal vaccines, for example, protect kids against many different types of the Streptococcus pneumoniaebacteria, which is the most common bacterial cause of ear infection, sinus infection, pneumonia and meningitis in children. Everyone over 6 months of age should receive the flu vaccine each year. COVID-19 vaccines should be kept up to date based on the most recent Centers for Disease Control (CDC) recommendations. All vaccines are helpful because they will train your child’s immune system to recognize these harmful pathogens without experiencing the actual illness, and this is the best “boost” you can give to your immune system.
Relevant reading
Mayo Clinic Guide to Raising a Healthy Child
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