RSV in children and infants

RSV in children and infants

Long before the outbreak of COVID-19, there existed a respiratory virus named RSV (Respiratory Syncytial Virus), that went around during the winter months, every year.
The RSV virus causes a respiratory infection that is actually one of the most common infections in children. In fact, by the age of 2 years, almost every child will have already contracted the virus, at least once. Therefore, it would be a real blessing to be able to prevent this infection in all kids.
The good news is that in most cases, the illness comprises of a fever, a runny nose and cough all of which resolve spontaneously, within a few days. And the bad news is… well, I’ll explain everything in this post.

What is the RSV? Where does the name come from?

RSV stands for Respiratory Syncytial Virus, which is the full name of the virus that causes the illness we are about to discuss. RSV is a respiratory virus that has 2 different strains, each of which have several sub strains and they all like to go around and get little kids sick every winter season.
The root of the words syncytial, by the way, stems from “syncytium” which is Latin for the effect that the virus causes on respiratory cells in the lab. It causes many little cells to stick together and form large cells – which is what this word means. It’s pretty cool to know this stuff, don’t you think?

Who is at risk of getting RSV?

Everyone, from young kids to oldies.
Almost all babies under the age of 2 will already get RSV at least once. If it doesn’t happen in their first winter, it will happen during their second. In addition, just like in most other respiratory viruses, you’ll be glad to find out that you can get RSV several times in your lifetime (because of all the different strains and sub strains that exist). However, usually recurrent infections will be milder.
Note that RSV can also cause illness in elders, as well as older kids with chronic illnesses, especially those that are immunosuppressed, those with chronic lung diseases and those with chronic cardiac issues. See more about this below.
So, lets summarize this. Who can get RSV? Everyone.
Who is more prone to it? Babies or older kids with underlying illnesses on their first encounter with the RSV virus and older adults who have lots of underlying diseases.

How does RSV transfer?

No surprises with this one.
The virus infects humans only, and since this is a respiratory virus one can catch it if they come in close contact with respiratory secretions (mucosal discharge and saliva), with drops of saliva from a child who has RSV, or by touching objects that another child with RSV had put in their mouth. Additionally, the virus may survive well for several hours on surfaces, including hands of people who have touched infected objects.
The incubation period of this virus is usually about 4-6 days.

When is RSV most common?

Up until the outbreak of COVID, this question was straight forward and was easy to answer. RSV would usually break out during the winter months each year. There was not a single case of RSV during the winter months when COVID first broke out, but then we started seeing cases in summer (of 2021). In countries that have RSV vaccine, this led to vaccines being given over the summer months, as well. Recently, however, we have to started seeing RSV cases in the winter again, and it seems like nature is coming back to its roots…

What kind of symptoms does RSV cause?

RSV is a respiratory virus that causes an illness in the respiratory tract. It is the most common cause of respiratory illness in children under the age of 1 in the winter months and it is the culprit behind most hospital admissions and doctor visits among pediatricians during this time. Before we continue, I hope you have already read my post about winter illnesses in children. I feel that it provides the basis for this post, and it contains all the definitions of upper and lower respiratory tract illnesses, etc. Anyway, if you haven’t already done so, I suggest you read it.

So, what does RSV lead to in children?

RSV causes an upper respiratory tract illness (URTI).
In most cases children will develop an illness of the upper respiratory tract including a runny nose and cough. Often, they will have fever and difficulty feeding because of their congestion. It is supposedly a mild illness but can be very irritating because of how difficult it makes it for infants to eat and get by with their daily life activities.
RSV can cause a lower respiratory tract illness (LRTI), too.
In 20-30% of children, the virus transfers from the upper tract to the lower tract (what some people refer to as – “made its way down to the lungs”, do me a favor and refrain from using this phrase), and may lead to a viral pneumonia. How does this pneumonia manifest clinically? Similarly to the way an asthma attack would present in older children, with shortness of breath and wheezing.
This sort of illness is referred to as “bronchiolitis”, which describes an inflammation of the narrow respiratory airways in the lungs that get filled up with mucous and inflammatory tissue.
Bronchiolitis typically lasts 3-5 days and consists of fever, a runny nose, a cough and respiratory difficulties. The symptoms peak around the 4th day of illness. These typically lasts for 2 more days before they start improving. An irritating cough may last for 2-3 weeks before it gradually begins to improve.
Often, the breathing difficulties lead to a reduction in oxygen saturation levels in the blood and the child is admitted for supportive oxygen therapy and fluids.
What else? These kids with bronchiolitis are usually under the age of 1, and they usually visit their doctor a couple times throughout the course of their disease. They may be given inhalers and nebulizers, or even antibiotics – which are completely redundant, as we will learn below.
What do I really want to say? Prevention of RSV can save both parents and the pediatricians from all of these shenanigans, and from many redundant visits and treatments.

Apnea (a cessation of breathing)

In babies, RSV can cause irritability, lethargy, difficulties feeding and less commonly apnea and cyanosis. These symptoms require hospital admission for observation.
So, if you have a newly born little one in the house, under the age of one ore even two months and their older brother/sister are not feeling well, try to prevent them from contracting their sibling’s infection.

Secondary bacterial infections

Sometimes, but not very often, some kids with a viral infection (RSV or any other infection) develop a secondary bacterial infection in their ear (read more about this here) or in their lungs (more here). The source of such secondary infections are bacteria that settle on top of the viral infection.

Some important points regarding mortality and bronchiolitis
– RSV is not the only virus that can cause bronchiolitis in infants and children, but it is the most common one.
– Remember, most children will RSV will not get bronchiolitis but only an upper respiratory tract infection.
– Remember that most children with bronchiolitis will not need to be hospitalized, and are able to manage without any special treatment (only about 1-3% require hospitalization).
– There are several groups of people that are at higher risk of developing severe illness and will need hospitalization and respiratory support (some of these groups of children are also given the RSV vaccination as part of their routine vaccine schedule, as you will see below):
o Healthy babies – especially in the first 6 months of their life, and more so in the first 3 months of their life.
o Babies that were born small and prematurely.
o Children with chronic lung disease.
o Children with cardiac diseases – cyanotic heart disease, heart failure and pulmonary hypertension.
o Children who suffer from immunosuppression.
o Children with difficult neurologic illnesses and neuro-muscular diseases that make it difficult for them to swallow respiratory secretions and saliva.
o Elders over the age of 65, especially those with underlying illnesses as mentioned above. But, lets stick to children for now. By the way, if you are an adult over the ae of 65, I suggest you read the chapter about pneumonia vaccines in adults, here.

How is bronchiolitis diagnosed?

The diagnosis is made by pediatricians and it is clinically-based.
The child with RSV will be at an age consistent with the infection and will have a medical history that includes a runny nose, cough and fever. Physical examination will usually reveal fast breathing and diffuse crackles and wheezing are heard upon auscultation by the pediatrician. All these signs and symptoms suggest an RSV infection, and there is no need for any further testing. In the past I used to test these kids for RSV (rapid-antigen testing) at my clinic. But with time I have found that there is no need for this.
At the rare times when a secondary bacterial pneumonia is suspected, blood work and chest x-ray may be carried out to aid with diagnosis. It is important to note that since the virus itself may cause a viral pneumonia, it is very difficult to distinguish between a viral pneumonia and a bacterial pneumonia (a result of a complication), on x-ray.
Or, in other words, if a pediatrician decided to order a chest x-ray for every other child, he will probably end up prescribing antibiotics because there is almost always an involvement of the lungs and it is difficult to tell whether it is viral or bacterial.
As I have previously mentioned, in most cases there is no need for further workup as such workup will not affect management and the illness will resolve spontaneously, regardless. In hospitalized children a PCR test can be carried out (together with PCR testing for other pathogens – you all know so much about PCR testing now). However, even then, a positive result will not affect the management of the child. Management is affected mostly by the child’s respiratory state.

What are the red flags that indicate severe bronchiolitis? What signs should we observe and follow up on?

As I mentioned above, bronchiolitis typically reaches its peak, in terms of severity of symptoms, around the 3-5th day of illness.
Here are some of the important signs that indicate the need for an immediate medical assessment:
1. Worsening shortness of breath – the child is breathing at a fast rate, even after his fever goes away. How can you tell that your child is putting a lot of effort into breathing? Observe the use of his muscles to try and get more air in. You will be able to see his nostrils flare up with every breath. Also, there is an emphasis of the space between his ribs, under his ribcage and above the main bone in his chest. Sometimes, you can really hear him wheezing and a lengthening of the expiratory phase of his breathing. In severe cases, you will be able to hear him grunting and in very severe cases there will be a temporary cessation of breathing and his skin will turn blue.
2. A substantial decrease in the amount of food intake – generally speaking, it is okay for a sick child to eat less. It is very normal. The runny nose, the secretions and the breathing difficulties make it harder for the child to feed. How much of a decrease is still okay? Usually, if the child is eating approximately one half of what he normally eats, then that is a good enough amount for him to remain hydrated. But if the amount is reduced to about two-thirds, you should take extra care and follow up on him. Check to see how much of his bottle he is able to take in and follow up on the number of wet diapers you are changing per day. If both of these are significantly reduced in comparison to his normal self, you need to see a doctor. Urine output varies depending on age. But, as a rule of thumb, if your child hasn’t given any urine for more than 12 hours then you should really see a doctor.
3. On examination by a physician (in addition to all of the above) – some primary care physicians have devices that check for oxygen saturation levels at their clinic. A decrease in the oxygen saturation levels indicate a decrease in the ability of the lungs to provide oxygen for all the tissues in the body. This is a simple test and it is not painful. The way it works is that the device is attached to the child’s fingernail, toenail or ear and it measures the number of red blood cells that carry oxygen in the blood, optically, using infra-red rays. It may require some patience as it takes a few minutes until it gives a reliable measurement (the baby needs to be still). Values below 90% require oxygen supplementation, medical observation and follow up measurements. Remember that saturation levels fall when we are asleep due to an accumulation of secretions in our respiratory tract and a reduction in our breathing effort. So, it is very important to measure the saturation levels when the child is asleep if they are borderline normal when they are awake.

Okay, so how do we treat RSV?

Most children do not require any treatment apart from antipyretics for their fever and making sure they are feeding well enough so that they do not get dehydrated.
Assessment and follow-up by an experienced pediatrician is always good to have.
Most of the time, all you have to do is wait for the ‘peak’ to pass before the child starts getting better slowly.
The hardest thing for a pediatrician to do is try and convince parents that their child’s illness is ‘viral’ and there is ‘no real treatment for it’.
All of the following are NOT useful in RSV infections:
Cough syrup – there aren’t too many syrups that are suitable for children under the age of two, anyway, but regardless, these aren’t useful.
– Humidifiers – in the past parents would place humidifiers in their children’s rooms. These cause more harm than good because they can burn kids if they get too close. These days, some parents place cold humidifiers – not useful either.
Nasal drops for congestion – these make no difference to the course of illness
Suction of nasal discharge – I was once offered to have this suction tube that connects to a vacuum, imported to the country. Looks like nasal discharge suction in children is a sport in some countries. It does not work!!!
Nebulizers – read about the difference between nebulizers and inhalers in children here. Not only do we refrain from using nebulizers in kids these days (we always prefer inhalers), neither of these work in bronchiolitis! I’ll talk more about bronchodilators below.
Hypertonic saline nebulizers – every time there is an infection that has no real treatment, the market starts offering all sorts of things that haven’t been proven to be medically useful. This is one of them. It is not harmful, but it just doesn’t change anything. Hypertonic saline nebulizers are good for parents that want to feel like they are doing something for the child, and for the pediatrician to buy some more waiting time.
Steroids – not in any form. Not as inhalers, and not by mouth.
Leukotriene inhibitor drugs – these are only given to certain people to prevent asthma attacks.
Antibiotics – big no!!! It is simply useless in bronchiolitis. And this was researched thoroughly in lots of scientific studies.

So, what can we do at home in addition to antipyretics and observation?

I really do understand how difficult it is to just sit there and watch your kid suffer. So, I have put together some of my recommendations:
Saline nasal sprays and nose drops may help reduce the thickness of the nasal discharge and allow for suction with a rubber pump. Be sure to be gentle, it is not always very helpful and for some kids it is just more irritating than the discharge itself. In addition, all that you have suctioned out usually refills within half an hour because of the irritation that the pump causes to the mucous membrane of the nose.
In children with a history of wheezing/asthma – i.e this is not the first episode of wheezing in the child. Only in those children can inhalers, bronchodilators and steroids be useful. Just as they would have, had the child had a different viral infection. Honestly though, these aren’t very helpful in most cases of RSV. When a pediatrician hears wheezing in these kids, he can’t be certain it is bronchiolitis. So, a trial for two days can be carried out to see if there is any improvement with symptoms. Read more here of bronchodilators use in children.
I’d like to make a few things clear with regards to this clause:
The hospital does not have any ‘magic’ treatment for bronchiolitis in healthy children either. I have treated thousands of kids admitted due to bronchiolitis. The therapy usually includes respiratory support (anything from oxygen supplementation to intubation and mechanical ventilation, rarely, intensive care is required too), fluids for children who are having difficulties with feeding, observation and reassurance for the parents.
Lots of children suffer an irritating cough that may last 2-3 weeks after RSV infections. It is annoying, yes, for both the child and the parents but it is part of the natural history of the illness, and no syrup of any sort, be it colour, flavor, natural or herbal is useful; only patience.

Can RSV infections lead to asthma?

The million-dollar question.
It is hard to tell. On the one hand, all children are infected up until the age of 2 and very few suffer severe disease. On the other hand, those who experience a severe infection are more prone to developing asthma later in their life. However, other viruses may cause the same symptoms too, so it is difficult to tell which one of them is the culprit for the asthma or whether it is simply genetics that cause the child to develop severe bronchiolitis and later develop asthma.
That is, it is hard to tell whether the child who got severe RSV and later developed asthma did so because of the virus, or whether he experienced a difficult viral infection because of his tendency to develop asthma and his recurrent episodes of wheezing. Another claim against the correlation between RSV and asthma is that when premature babies and infants who were vaccinated for RSV were followed up on, they were not found to have less cases of wheezing, asthma or changes in their respiratory function tests at the ages of 3 and 6 years.

Can RSV be prevented?

COVID-19 has taught us how difficult it is to prevent the transfer of respiratory illnesses. Almost all children under the age of 2 will get RSV. Nonetheless, there are two kinds of prevention methods:
1. Prevention of exposure as much as possible, especially in children at risk of developing severe infection. Try to avoid exposure to sick children and ensure good hand hygiene. The RSV virus is usually brought into the house by children who go to kindergarten. They only suffer a runny nose. But, if you have a baby in the house, take extra precautions and ensure good hand hygiene during the RSV season.
2. Vaccines.

What kind of vaccines do we have for RSV and who qualifies for them?

One of the vaccines available for RSV is Palivizumab (Abbosynagis).
This is a passive vaccine, which means the body receives antibodies that are already active against the virus and does not produce antibodies itself, like in most of the other routine childhood vaccines. Palivizumab (Abbosynagis) is an antibody targeted against one of the proteins that surround the virus. It prevents the virus’ attachment to the cells in the respiratory system, and by doing so it prevents its replication inside the body.
The vaccine is given as an intramuscular injection, once a month, for 5 months during winter. In 2021, due to the outbreak of RSV during the summer months after the outbreak of COVID, some countries decided to vaccinate children during the summer months as well. This was an exception.
The vaccine does not prevent the infection but was found to decrease the number of admissions due to RSV, especially in high-risk groups. Different countries have different criteria for eligibility for vaccination. Some of these criteria may include:
– Premature babies in their first year of life, born before 32 weeks, 6 days’ gestation
– Premature babies in the first six months of their life, born before 34 weeks, 6 days’ gestation
– Children in their first year of life, who weighed less than 1 Kg at birth.
– Premature babies in their first year of life who have BPD (broncho-pulmonary dysplasia): a lung disease that manifests with a typical chest X-ray at a corrected age of 36 weeks’ gestation and who required one of the following therapies: oxygen, diuretics, steroids or bronchodilators.
– Premature babies in the first 2 years of their life who have a chronic lung disease and require permanent oxygen supplementation.
– Children in their first year of life who have a congenital heart defect, including those with heart failure who are on medication, those with moderate to severe pulmonary hypertension and those with cyanotic heart disease.
Note how the list above does not include children who are immunosuppressed nor those with neurologic diseases, etc. The reason behind this is the lack of scientific research proving a reduction in admission rates, mortality and morbidity in such groups as opposed to the cost of the vaccine (it is quite expensive).
Nonetheless, in some countries physicians can request that their patient be considered for eligibility for the vaccine, if they believe he/she could benefit from it.
There are no side effects that have been associated with the vaccine except for mild local symptoms at the site of injection. It is also not intended for treatment of bronchiolitis, rather for prevention.
Refer to your national health regulation websites to find out whether your child qualifies for the vaccine.

What does the future hold for vaccines against RSV?

A research study published in July 2022 in the prestigious New England Journal of Medicine studied the efficacy of a newly produced, passive antibody against the protein coating of the RSV virus. This antibody can be given once at the beginning of the RSV season instead of monthly for 5 months. The link to this paper can be found here. In this study the vaccine was given to 969 premature babies born between 29 -34 weeks while 484 received a placebo. In the group that received the vaccine there was a 70% reduction in the number of bronchiolitis cases and a 78.4% reduction in admissions throughout the 150 days following the vaccine administration. It is interesting that among those children who were hospitalized due to RSV infection, all those who required intensive care or ventilation where those who had received the placebo and there were less children who had received the vaccine and suffered severe symptoms who required oxygen therapy. The side effects were mild and insignificant.

This new vaccine named Beyfortus (Nirsevimab) in now available in some countries over the workd, read all about it here. Moreover, a newer article shows an efficacy of 83%, read more here.
In addition, several other vaccines are being developed for RSV, some of which are in their preliminary pre-clinical stages. None of these have been approved yet.

To summarize, I think RSV is a reminder of one of the most common viral infections during infancy and it is a leading reason behind doctor visits during the winter months (even though there are other viruses out there…). I have seen children hospitalized due to severe RSV infections ten times over severe COVID-19. The good news is that despite it being so common, most of the time its symptoms are mild and only include a fever and runny nose, which do not require anything beyond antipyretics and observation at home before resolution within a few days.
Remember that RSV can lead to a viral pneumonia referred to as bronchiolitis, and that this could present similarly to asthma. Bronchiolitis too, resolves spontaneously in most children without any treatment (despite all the different types of useless therapies given by pediatricians). Being aware of the typical red flags will allow parents to refer to medical help when needed, in the rare times when the child symptoms are severe. It is important to make sure that children in high-risk groups, who qualify for the vaccine, receive it, so as to provide them with the maximum protection they can receive against severe infection and hospitalization.
Wishing us all an easy and virus-free winter!




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