This week, the US Food and Drug Administration (FDA) approved the world’s first respiratory syncytial virus (RSV) vaccine. The shot, named Arexvy, is approved for adults aged 60 years and older and was developed by GlaxoSmithKline (GSK).
GSK says the RSV vaccine will be available for older adults before this year’s RSV season, which usually starts before the winter months. Arexvy is administered through a single intramuscular injection.
RSV is a negative-strand RNA virus that was first identified in 1955. It is a highly contagious virus that can cause respiratory infections, such as bronchiolitis or pneumonia, in people of all ages. The virus is transmitted through droplets or direct contact and infects the epithelial cells of the respiratory mucosa, leading to lower respiratory tract infections, bronchiolitis, or pneumonia.
Symptoms of RSV infection include flu-like symptoms, such as coughing, sneezing, runny nose, fever and wheezing.
Research has shown that RSV can interfere with the function of dendritic cells, which are important in initiating an antiviral response. This interference can lead to a reduction in the antiviral T-cell response, or in some cases, the activation of unwanted pro-inflammatory T-cells, which can result in severe lung infections.
While most people recover within a couple of weeks, infants and older adults are at a higher risk of severe complications. The US Centers for Disease Control and Prevention (CDC) reports that RSV causes 60,000 to 120,000 hospitalizations and 6,000 to 10,000 deaths among adults 65 years of age and older in the US each year.
“Older adults, in particular those with underlying health conditions, such as heart or lung disease or weakened immune systems, are at high risk for severe disease caused by RSV,” said Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research (CDER), in the FDA’s press release.
“Today’s approval of the first RSV vaccine is an important public health achievement to prevent a disease which can be life-threatening and reflects the FDA’s continued commitment to facilitating the development of safe and effective vaccines for use in the United States,” added Marks.
Who Should Get the RSV Vaccine Arexvy?
Arexvy is approved by the US regulators to prevent lower respiratory tract disease (LRTD) caused by RSV in individuals aged 60 years and older. This age group is at a higher risk of developing severe complications if infected with the virus, which can result in conditions such as chronic obstructive pulmonary disease (COPD), asthma and chronic heart failure.
Therefore, it is important for older individuals to seek medical advice regarding RSV vaccination and to seek medical attention if they experience any symptoms of RSV infection.
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Efficacy and Safety of the RSV Vaccine
The FDA’s approval of Arexvy was based on GSK’s rigorous Phase III clinical trial AReSVi-006 (Adult Respiratory Syncytial Virus). In the trial, around 12,500 participants received Arexvy and 12,500 participants received placebo.
The trial results showed that Arexvy significantly reduced the risk of developing RSV-associated LRTD by 82.6 percent and the risk of developing severe RSV-associated LRTD by 94.1 percent.
Furthermore, the RSV vaccine was found to be 94.6 percent effective in older adults who had at least one pre-existing medical condition of interest, such as certain cardiorespiratory and endocrine-metabolic conditions.
The study identified injection site pain, fatigue, myalgia, headache and arthralgia as the most common side effects. It was reported that ten individuals who received Arexvy and four individuals who received a placebo developed atrial fibrillation by day 30 after vaccination.
In two separate studies, Arexvy was administered to around 2,500 participants aged 60 and above. In one of these studies, where participants received Arexvy along with an FDA-approved influenza vaccine, two individuals developed acute disseminated encephalomyelitis (ADEM) at seven and 22 days after vaccination. ADEM is a rare autoimmune disease marked by sudden inflammation of the brain and spinal cord. One of these participants passed away. In the other study, one participant developed Guillain-Barré syndrome nine days after receiving Arexvy. Guillain-Barré syndrome is a rare disorder where the immune system mistakenly attacks healthy nerve cells, leading to muscle weakness and, in severe cases, paralysis.
As a result of these findings, the FDA has mandated GSK to conduct a postmarketing study to assess any signals of Guillain-Barré syndrome and ADEM. GSK has also volunteered to include an evaluation of atrial fibrillation in the postmarketing study, despite it not being required by the FDA.
What is the Price of Arexvy?
While the cost of the RSV vaccine has not yet been disclosed, GSK executives have suggested that the price of Arexvy is expected to be between $60 and $185 per dose, which reflects the prices of their influenza and shingles vaccines, respectively. In addition, GSK is working with insurance companies to try to make the RSV vaccine accessible and eligible for reimbursement.
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Other RSV Vaccines that Could Arrive Soon
Several RSV vaccine candidates are currently in advanced stages of clinical development. In a Phase III trial, Pfizer’s maternal RSV vaccine candidate RSVpreF showed 81.8 percent efficacy against severe lower respiratory tract illness due to RSV in infants through the first 90 days of life. The efficacy went down to 69.4 percent through the first six months of life. An efficacy of 85.7 percent was observed in participants 60 years of age or older. Pfizer is anticipating the FDA’s decision for RSVpreF in August 2023.
Moderna also reported positive Phase III results for its RSV vaccine hopeful, mRNA-1345, showing an efficacy of 83.7 percent against RSV lower respiratory tract disease in adults 60 years or older across 22 countries, with no significant safety concerns identified.
These promising results from RSV vaccine candidates provide hope for the prevention of RSV infections, especially for vulnerable populations such as infants and older adults.
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