Respiratory Syncytial Virus – Old Problem, New Solutions
Respiratory Syncytial Virus, or RSV, has long been a known cause of bronchiolitis in infants and children under age two. Bronchiolitis is an infection of the smaller airways of the lung. It can be caused by several different viruses, but the most well known is RSV. I have discussed bronchiolitis in a previous article, which you can find here.
We are revisiting bronchiolitis, and RSV in particular, due to some new developments in research and treatments with vaccines that have been recently revealed and approved. RSV is one of the most common causes of hospitalization in infants less than a year old, many due to difficulty with keeping oxygen levels up, or due to dehydration if they are struggling to eat and drink adequately through their congestion.
Symptoms of RSV
RSV infections usually begin with fever and typical cold symptoms. These will commonly progress and include wheezing, which is a high-pitched whistling sound produced during expiration (breathing out). This wheezing is caused by narrowing of the small airways in the lungs, as a result of inflammation or swelling. This inflammation, if severe, can lead to difficulty breathing and decreased oxygenation of the blood.
As I described in my previous article on bronchiolitis, I like to think of the lungs like an upside-down tree. The trunk of the tree represents the trachea, or large breathing tube in the throat. The larger branches are the the bronchi, or larger tubes of the airways in the lungs. The smaller branches are the bronchioles, which are smaller airways. The leaves are the alveolae, which are the small sacs in the lungs where oxygen is exchanged. This is why RSV infection can lead to difficulties with keeping the blood oxygen levels stable – it is hard to get oxygen from the alveolae to the blood when they are filled with fluid.
How do we treat RSV?
- Symptomatic care: most infants and toddlers with RSV will only require symptom management. Lots of oral fluid intake, and nasal saline to flush out the mucous and nasal suction to pull it out. Keeping fevers down with medications helps them to feel better as well.
- Supplemental oxygen: decreased oxygen levels in the blood is sometimes found in infants dealing with RSV, and is one of the most common reasons for hospitalization. Most of the time these infants can be treated with supplemental oxygen through a nasal cannula, but sometimes it is more severe and requires higher levels of care. This oxygen support will not be necessary once the infection has resolved.
- Intravenous fluids: another common reason for hospitalization is dehydration. Infants struggle to get enough oral liquids when they have severe congestion, and this leads to dehydration. Sometimes this needs to be treated with intravenous (IV) fluids. Affected infants usually feel much better once the dehydration has improved.
- Palivizumab (“Synagis”): premature infants and those with some congenital heart and lung diseases have been previously treated with Synagis. This is a monthly injection of RSV antibody that helps to prevent infection or severe disease with RSV in this very vulnerable population.
Many studies have been done to look at the effectiveness of treatments and medications that work for other lung diseases, such as asthma or pneumonia, but unfortunately not many have been successful or made much of an impact in the disease process. Breathing treatments with albuterol are only effective in treating wheezing about 25% of the time for bronchiolitis. Oral steroids have not been shown to make a difference at all. Antibiotics do not help because the infection is caused by a virus.
Understanding the New Vaccines
There are two new RSV vaccines as well as a new RSV immunization. While these don’t sound like they would be different, they actually are.
RSV vaccines work like all other childhood vaccines – a part of the virus has been selected to be presented to the immune system to create an immune response without causing the disease itself. There are two RSV vaccines that have been approved by the FDA recently, one specifically for adults over age 60 years and one that can be given to older adults as well as to pregnant mothers between 32 and 36 weeks of pregnancy. This vaccine, RSVpreF, has been shown to decrease hospitalization of infants by 57% in the first six months of life.
RSV immunization is an injection of pre-made RSV antibodies (similar to the Synagis injection mentioned earlier). This new RSV immunization is called Nirsevimab. It has been shown to decrease hospitalizations and office visits by about 80%. Unfortunately, both Nirsevimab and Synagis provide “passive immunity” by providing antibodies to the infant, and this does not stimulate an immune response. Antibodies that are given rather than made by the body have a limited life-span and eventually go away. These antibodies can help protect the infant through the RSV season but cannot provide long-term protection against RSV infection.
Final thoughts
As a Pediatrician who has been battling against RSV for over 15 years, I am excited about these new developments (though I admit to being frustrated that it took the recognition of this disease in older adults for there to be such a strong push for vaccine development). For too long, we have only had a few options for treatment that have proven to actually be effective. Although lots of research has been done to see if any of the treatment methods for other lung diseases would help, such as breathing treatments and steroids, nothing made much of a difference other than time and oxygen and allowing the body to fight off the infection.
Any time we can prevent disease – as opposed to waiting for it to occur and then treating the effects – should be considered a win for both patients and medical providers. Throughout the modern history of medicine, vaccinations have been proven to be a powerful method of prevention of disease. Hopefully these new vaccination options for RSV will demonstrate the same effect and will lessen the burden of respiratory illness on our youngest and most vulnerable patients.
Resources
Healthy Children.org: https://www.healthychildren.org/English/health-issues/conditions/chest-lungs/Pages/RSV-When-Its-More-Than-Just-a-Cold.aspx
Maternal RSV vaccine: https://www.cdc.gov/media/releases/2023/p0922-RSV-maternal-vaccine.html
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