If Vaccines Work, Why Are Vaccinated Kids Still Getting Sick?

If vaccines work, why do vaccinated children still get sick?

It’s one of the most common questions parents ask—and one that often causes confusion and doubt.

In this episode of Healthy Beginnings, Dr. Edgar Kalimba explains how vaccines actually work, why no vaccine is 100% perfect, and why vaccinated children can still develop some illnesses.

Vaccines are designed to protect children from the most dangerous infections and complications—not necessarily every cough, fever, or illness. Understanding this difference is key to making sense of childhood sickness.

In this episode we discuss:

•  Why vaccinated children can still get sick 
•  What vaccines are designed to prevent 
•  Why some illnesses are milder after vaccination 
•  How immunity develops in children 
•  The role of herd immunity and community protection 
•  Why vaccines still remain one of the most effective tools in medicine 

This episode is designed to help parents understand vaccines with more clarity, less fear, and greater confidence.

Healthy Beginnings offers clear and evidence-based conversations about children’s health, family wellbeing, and the systems that shape our lives. 

New episodes every Monday 

Have a question? Email: healthybeginningspodcast@gmail.com

Produced by LF Media

Transcript

SPEAKER_01 0:00

A very happy Monday to all our listeners. I'm very glad that you've all been listening over the past couple of conversations. I've gotten feedback. People have um sent me comments and uh really telling me that the conversations have been useful and informative. So that's encouraging and uh we'll keep going and we really plan to tackle as many health topics that really impact uh the earliers of our children. As parents, all we want is to see our children grow well, be healthy, thrive, and do well in life. And I hope that as we go along with more and more conversations, we will together be able to achieve this. So today I would like to discuss what I would call our final episode on vaccines. The last two episodes have unpacked uh different angles and different common scenarios and questions regarding vaccines. And um I noticed that from a couple of feedbacks that there's a question that I should address today, which you know, sometimes as healthcare providers, we take for granted. But it's I think a good question. And the question is if vaccines work, why do children still get sick? Right? Very good question. And um many parents quietly wonder about it even without asking a direct question about this. If my child is vaccinated, why do they still get sick? Very fair question and an important one. Because understanding the answer helps you to see what vaccines really do and why they remain one of the most powerful tools that we have to protect our children, as I mentioned in our previous conversation. So today, in the next 20 or so minutes, we'll walk through a quick recap on how vaccines work and why immunity differs from child to child, and why vaccines are not 100% effective. Indeed, why do vaccinated children still get sick? I'll speak briefly about hard immunity as well and what it means for your family. And again, we'll recap on why completing full vaccine schedule and doses matters. So a quick recap on how vaccines work. And at the core, vaccines are really training tools for the immune system. So what they do is we introduce a harmless part or a weakened version of a microbe or a germ into the body, and this allows your baby's immune system to recognize the germ, learn how to fight it, and remember it for the future. And this is important so that when the real infection shows up later, the body can actually respond faster and more effectively compared to an innate or um a child's immune system that is dealing with this particular microbe for the first time. So you could think of it like a fire drill. You know, you practice before the emergency. You know, people who are firefighters are always practicing. If a fire springs up, these are the steps. This is what we do, this is how we respond to make sure that we are effective and victorious in conquering this fire. And that's exactly what vaccines do. They prepare the immune system before the real threat appears. And this takes me to the other item, which is why immune responses differ. Why are some children presumably more sick than others? Why, even with getting vaccines, um what is it that really makes the responses differ? And there's several factors. You know, I would almost give an example of um, you know, the fact that every baby is unique. They are unique in their features, they are unique in their DNA imprint, they are unique even in weight and height and all of that. So, in a way, our immune systems are also quite unique. No immune system or immune response of an individual would be uh exactly the same as the other individual. Even in um identical twins, they are still uh unique as individuals. So several factors do influence how we respond and how strong our immune response would be. Uh, first of all, it's age. So we know, for example, that younger babies uh may not respond as much as older babies or may not respond the same way. And parents who've had preterm babies or babies born before the right time, born small, you might have noticed that we generally wait for them to attain a certain weight and a certain age to be able to actually initiate uh vaccines, the routine vaccination calendar. Exactly the same reason why we don't give all these vaccines immediately when the baby is born. You know, we we stagger them. Some are given at six weeks, others ten weeks, fourteen weeks, six months, nine months, fifteen months, and on and on. So age is a factor. The second thing is nutritional status. So nutritional status um also does matter. Um, underlying health conditions, so for example, there are some babies that are born with what we call primary immune deficiencies or who do not respond as much as uh their peers do. So the general health of the baby, some environmental factors, but also very importantly the genetics. The genetics are a little bit complex, but again, when you go to the genetic makeup, there's uh a uniqueness that really is part of what drives how we respond in terms of the immunity. So understandably, some children develop very strong immunity after vaccination. Others develop good but slightly lower protection. This does not mean that the vaccine failed, it just means that the immune system responded, um, but to different degrees and not in the same way from child to child. This is a normal uh biological variation, and again, it's what makes every child unique. So, in essence, vaccines are not 100%. We don't have any vaccine that has efficacy of 100%. Most have very good efficacy, uh, typically between 85 and 95%. Uh, you're if you remember back in the COVID days, they used to talk about efficacy, saying that you know, uh such and such a vaccine has 80% efficacy or 90% efficacy. And what it means is really that if you take 100 people, for a vaccine that has a 90% efficacy, it means that 90 out of these 100 people will actually respond to a good and acceptable immune response. They would be protected. There will, however, be 5 to 10% that would have responded, but not maybe not as good and not as much as the others. So this invariably means that a small percentage may still get infected, even though they got vaccinated. But here is the key point that I really want to make clear. You know, vaccinated children who do get sick, who get sick, which they will, usually have much milder illness. So instead of very severe complications, or instead of needing to be hospitalized and admitted for, let's say, prolonged intravenous antibiotics, your child might get sick and then they take an oro antibiotic and they are well because the immune system actually did prevent the disease from becoming very severe. And that clearly has a protection against long-term damage. So they are more likely to experience mild symptoms, faster recovery, and a lower risk of spreading the disease. So, again, this is the point where we remind ourselves that vaccines don't just reduce infection, they reduce severity. And that is pretty much life-saving. Now, this takes me to the discussion around herd immunity. I did mention this concept briefly in my previous conversation, but I would like to zoom out from the individual child to the community. Herd immunity happens when enough people in the population are vaccinated, making it harder for a disease to spread. And this is important. It means that we are each other's keeper. It means the more children are vaccinated, the broader the protection within that particular community. And so, for example, we do not give all these very many vaccines to a baby immediately after birth. So, meaning there's a period of time where as babies go through the vaccination calendar, they are not entirely protected from what is circulating in the community. Obviously, newborns usually get antibodies from their mothers. A healthy mother would have transferred a good lot of antibodies that protect against a lot of different infections. But when herd immunity, when a community has very high levels of vaccination, newborns who are too young for some of the vaccines also get protected. The same thing with older people, because the extremes of ages both provide relative vulnerability. So it also protects children who have weakened immune systems. If they have a primary immune deficiency, maybe they were born with a problem in the immune system, or if they have what we call a secondary immune deficiency for one reason or the other, uh, they also get protected from the herd immunity. And there's always people for one health reason or another that did not develop full immunity, including adults. And this is where hard immunity actually plays a key role. So you can think of it like a building, uh like a building a wall where each vaccination, each vaccinated person is a brick. The more bricks we have, the harder it is for the disease to pass through this wall. But if too many bricks are missing, the wall weakens and outbreaks can happen. This is why we've seen um outbreaks of vaccinated, widely vaccinated diseases come back. Outbreaks of measles, outbreaks of um chickenpox, we've had small outbreaks of polio, particularly in uh in countries that are going through conflict. So it's history has really taught us this, and it's important that uh when your child is vaccinated, it doesn't just protect them, it helps to protect others around them. I believe this is very clear now, and um this is the key uh message that I wanted to deliver today in this conversation. Um, what should be noted is that vaccines are really not just about getting a shot, they're about getting the right doses at the right times. And this is why many vaccines require multiple doses and booster shots. Because again, immunity builds in stages. The first dose, as I previously mentioned, introduces the immune system to this particular antigen, microbe, uh, infective agent, and then later doses strengthen and extend protection. If doses are missed or delayed, protection may be incomplete and immunity may fade sooner. That's why it's important to stick to the recommended schedule, catch up if you fall behind, and do your best to complete the full series of the recommended calendar. So before I answer some of the questions from the listeners, and as we close this vaccine series, let's try and bring everything together. Number one, vaccines train the immune system before real disease strikes. Number two, each child responds differently, but must underline the word must gain strong enough protection. No vaccine is perfect, but they dramatically reduce severe illnesses. Again, vaccines are comparable to all the other medications, the same way we respond differently when we take medication, the same way our bodies respond differently and metabolize the products differently, it's exactly applicable to the vaccines. And importantly, hard immunity protects the most vulnerable among us. And completing the full schedule ensures the best possible protection. So when a vaccinated child gets sick, it doesn't mean vaccines don't work. I hope that this is clear. And choosing to vaccinate is not just a medical decision, it's an act of protection, not only for your child, but for all of us collectively as a community. Before we leave, I would like to answer some of the questions that were sent to us by the listeners.

SPEAKER_00 16:30

First question from Veronica from Kampala. My toddler struggles with constipation and it makes him uncomfortable and irritable. Could it be diet-related? And how do you manage it safely?

SPEAKER_01 16:41

Constipation is a very common complaint. In fact, it's probably one of the most common complaints that comes to us. Because constipation, it might sound mild, but at the core, it can be a very painful condition. If your baby hasn't passed stool for two weeks and they're struggling and they have very hard poop, it becomes very traumatizing and can be really, really a nuisance and a huge discomfort in the family. So there's two main things that I would speak about with regard to constipation. The first one is dietry. And unfortunately, I've I've noticed over the years, and I think we actually spoke about this in some of our earlier conversations. Um I think given the environment, given how busy parents are, um, our diet has changed quite dramatically. It's very common nowadays that some parents choose the easier route, meaning uh refined carbs or things like pastries and breads, uh, where you know your child gets eats refined carbs for breakfast, has white bread, packs that, or packs other pestries in the course of the day, barely has uh a decent amount of fruit. And when they are back home from school, naturally uh it's not a lot of children that are very happy to eat sufficient amounts of vegetables and legumes, they tend to prefer uh the alternative. Um, so that really is the most frequent cause of constipation, dietary. So, not eating sufficient amounts of fruit and vegetables and fiber and things that really help the digestive system to work well. So, at the core of it, it really calls to being very intentional as a parent. Um, all of us, including my children, it's not easy, but you have to model it yourself. That's one. We've discussed this before. It's important to at least have one meal a day where you sit together around the table, where you build good habits, but also demonstrate and model what should be put on the plate. Secondly, um hydrating sufficiently. Again, uh we differ from person to person, but it's not uncommon for um some of the children where you find that when you're not intentional, they're actually not hydrating enough, they're not drinking sufficient amounts of fluid, whether it's water or other um healthy uh other healthy drinks. So dietary, making sure that the choices, the options are sufficient to cover the the needs for fiber intake and and and making it easier and avoiding constipation, and secondly, to hydrate enough. Now there's something we call uh actually two medical conditions. One is not particularly a medical condition, but about 10% of the population have a long colon or a long part of the intestine. What that means is that when you eat, food particles stay longer and they get drier. And when they get drier, then you get constipated. So it's not uh a disease, but it's a nuisance, and that's why some people are more constipated than others. It's that natural biological difference. And that again requires more effort in terms of the dietary choice and in terms of um hydrating, the examples I gave. Some people will argue that, you know, I give my child fruit and they also eat reasonable amounts of vegetables. But on top of that, you also add a lot of wheat products and they have um crepe. Crepe is a common one in our setup where some kids eat that almost every day, and they've had snacks in between, and they've had white breads. So you kind of cancel out the good stuff that you you you gave. So it's interesting that sometimes when I tell parents to uh choose whole grain or whole wheat bread. Brown bread, they say, oh, that's for that's a dietary bread. That's for people who are not well. I'm like, no, no, no, no, no. That is actually what we all need. That's what we should all eat for those who love vestries and wheat products. Um, and then so that's the one thing where naturally some people have longer intestines, um, also called a redundant colon. And then there's another much rarer condition where part of your intestine actually doesn't have enough nerve supply. When there doesn't have enough nerves, nerve supply, it doesn't function as it should. Um, and the only way to tell if it's just constipation that needs a bit more of dietary discipline, or if you have a redundant colon, or if you have Hashpranx disease, which is a colon that doesn't function, everything goes and gets stuck there, uh, you would need to seek um uh a medical opinion. One thing that tells you that your intestines are probably fine and it's just dietary choices, if your baby was very well the first couple of months before you started solids, they used to poop two, three times a day or once in three days, which is also acceptable. Uh, that tells you that there are no problems. The intestine is actually fine. And since you started giving certain items, that's when you started running into problems.

SPEAKER_00 23:39

Last question from Linda 40 living in Kigali. Once my toddler discovered sweets and snacks, it became a daily demand. If we say no, it turns into a meltdown. How much sugar is too much at this age?

SPEAKER_01 23:52

So the two-year mark or uh children around that age, uh a lot of people like to refer to temper tantrums. So those are normal. You know, two-year-olds are going to have tantrums regardless. It's part of growth and development, it's part of them asserting themselves and challenging authority and having a voice. I think the key here is to um, as a parent, to stay a parent and to stay with authority. You know what's good for your child. Having uh sugary, high sugary treats every day is a big no. It's nutritionally empty, it doesn't help, and it's a very bad practice. So obviously, you're not going to give in to that. If your child goes for a birthday party once in two months and he has a treat or she has a treat, that is perfectly fine. I think that's reasonable. We all deserve that, even adults. But don't make it a daily thing. And you need to be practical. If you have a strong-willed child who will demand and scream and not give up, why buy it in the first place? Don't bring it at home. They're not going to see it, they're not going to demand it. But if you come home with a pack of lollipops and sweeties and all kinds of chocolate and all these things on a daily basis, then you're going to find yourself in trouble. So I always say that, and this is something I've practiced in my own house. Um, if I don't want to encourage something, it's not gonna come up in my home. So we'll have plenty of fruit, we'll have plenty of healthy snacks, um, and I'm not going to buy pack juices. We have water, drinking water available. And so, you know, your children learn to actually take what is available, uh, they learn to adapt and even like it, and the rest is treated as a treat, which it should be. Thank you for listening to Healthy Beginnings. If you have any questions you'd like answered in the next episode, you can submit them to our email, healthybeginningspodcast at gmail.com. You can also follow us on all social media platforms. You can find us on YouTube as well as the audio platforms of your choice. See you next week.

SPEAKER_00 26:30

This podcast is for general informational and educational purposes only. Do not make health decisions without consulting your doctor. This podcast is brought to you by LF Media, home of Great African podcasts.