For the First Time Ever, there will be an RSV (Respiratory Syncytial Virus) Vaccine Available this Fall for Older Americans
Respiratory Syncytial (pronounced “sin-sish-uhl”) Virus (RSV) is a common respiratory virus that for most people is little more than a bad cold resolving on its own within a week or two, but for infants (and some older children) and the elderly, it can be quite serious and even deadly. We generally see RSV activity from October to May each year in the U.S.
We divide how people present to our offices or emergency rooms with respiratory infections as upper respiratory tract infections (URIs) (those whose signs and symptoms are predominantly involving the throat and above – runny nose, nasal congestion, sore throat, and/or non-productive cough) and lower respiratory tract infections (those with signs and symptoms relating to the lungs – chest tightness, shortness of breath, wheezing, cough with sputum production, abnormal breath sounds when we listen with a stethoscope, and/or abnormal changes on the chest x-ray).
RSV is the major cause of lower respiratory tract infections in children. RSV is the most common cause of bronchiolitis (inflammation of the small airways) and pneumonia in children in their first year of life, and a common cause for hospitalization of young children during the cold and flu season. RSV is one of the respiratory infections that can cause croup (a protracted, barking-like cough and sometimes accompanied by a high-pitched creaking or whistling sound when the child breaths in).
Almost everyone will be infected with RSV within the first few years of their life. However, people do not develop a robust immune response and memory to RSV, so reinfections are common. (That is one of the reasons it has been so difficult to develop a vaccine against RSV.)
People generally develop symptoms within 4 – 6 days after being infected and symptoms generally include a runny nose, coughing, sneezing, wheezing and fever. Infants may stop eating or nursing due to the difficulty of doing so while working so hard to breathe.
RSV was first isolated and identified from chimpanzees with colds in 1956. Shortly thereafter, the same virus was identified in young children with respiratory illnesses. RSV is an RNA virus, as are influenza and SARS-CoV-2. By now, everyone is aware that the spike protein of SARS-CoV-2 is important in binding to the ACE-2 receptor on cells to enable the virus to infect the cell and is an important immune target for developing neutralizing antibodies (neutralizing antibodies bind the protein in such a way as to inhibit the virus’ ability to attach to the cell receptor and infect the cell). RSV is a completely different virus than SARS-CoV-2 and has a different structure and a different cell receptor it binds to.
Rather than the S (spike) protein of SARS-CoV-2, RSV has an F (fusion) protein that is important for fusing together the membranes of the virus and the cell to allow the virus to enter and take over the cell’s machinery to make new viruses directed by its RNA genetic code. During the process of infecting a cell, the F protein morphs from its pre-fusion structure, which has a number of sites that provide the body’s immune system with neutralizing antibodies to a post-fusion form, which provides the body with fewer and weaker neutralizing antibody targets.
There are two strains of RSV – A and B – but there are many subtypes of each.
On May 3, 2023, GSK’s RSV vaccine (Arexvy) using the prefusion form of the F protein was approved as a single dose vaccine for those 60 years of age and older for the prevention of lower respiratory tract disease from RSV infection. This vaccine was studied through two full RSV seasons. Lower respiratory tract disease was distinguished from upper respiratory tract disease by at least 1 lower respiratory sign or if no respiratory signs, at least 3 lower respiratory symptoms, lasting for at least 24 hours. (A symptom is something that a patient feels and reports, but generally we cannot objectively measure – e.g., sore throat, stuffy nose or shortness of breath, whereas a sign is something that we can observe or measure and the patient may not even be aware of– e.g., rapid breathing or low oxygen levels).
The vaccine effectiveness (VE) for Arexvy was 82.6% during the first RSV season following vaccination, 80.9% when measured mid-way through the second season, and 56.1% by the end of the second season. However, the VE against severe lower respiratory tract disease was better (as expected) and more durable (VE 94.1%, 86.8% and 64.2%, respectively). Interestingly, giving a second dose of vaccine in advance of the second season did not improve the VE.
The studies also showed that it was safe and effective to administer flu vaccine at the same time as the RSV vaccine (this is important for patient convenience so that they can make fewer trips given this population may have more mobility issues and difficulty driving or arranging for transportation).
On 5/31/2023, the FDA gave approval for Pfizer’s Abrysvo vaccine for persons age 60 and over for the prevention of lower respiratory tract infections resulting from RSV. The vaccine uses the F protein of the RSV in its pre-fusion form.
The VE was assessed against symptoms of lower respiratory tract disease symptoms over two RSV seasons (the RSV season of one year, followed by the mid-point of the next season one year later). The VE in preventing 3 or more lower respiratory tract disease (RSV-LRTD > 3 symptoms) was 88.9% for the first year and 78.6% at the mid-point of the second RSV season.
The VE in preventing 2 or more symptoms of lower respiratory tract disease (RSV-LRTD > 2 symptoms) was 65.1% for the first RSV season and 48.9% at the middle of the RSV season in the second year.
Studies of Pfizer’s RSV vaccine did not reveal any safety concerns and demonstrated that it could be safely administered together with the influenza vaccine, without any impairment to its protection against RSV.
This is wonderful that we now have two vaccines available for older adults to protect against a common respiratory infection that can cause respiratory illness serious enough to hospitalize 60,000 – 160,000 seniors each year, with 6,000 – 10,000 deaths expected each year.
However, there are still some challenges:
- It is not always possible to predict the onset of RSV season, and we have recently experienced some earlier upticks in disease than expected.
- None of the studies evaluated the safety and efficacy of administering RSV vaccine, influenza vaccine and the COVID booster shot that many older adults are going to want to receive this fall.
- Both new vaccines are approved for adults ages 60 and over, but what about those under age 60 who are immunocompromised?
If you are age 60 or older and are on the fence about whether to get this vaccine, I would use any of the following factors to push you over the fence to the side of getting the vaccine:
- You will be around young children during the cold and flu seasons (e.g., a grandparent of young grandchildren (especially 2 and under), working in a daycare setting, volunteering as a Sunday school teacher for young children, etc.)
- You have underlying lung problems (asthma, bronchitis, emphysema, etc.)
- You have significant underlying heart disease
- You reside in a skilled nursing facility or long-term care facility
- You are immunocompromised
If you have other underlying chronic medical conditions, be sure to discuss whether you would likely benefit from RSV vaccination with your doctor or other regular care provider.
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