Respiratory Syncytial Virus (RSV) is a common respiratory illness that often causes mild, cold-like symptoms. Historically, preventative measures for RSV have been limited, leaving vulnerable populations susceptible to its more severe effects. The landscape of RSV prevention has recently undergone a significant transformation, with new tools now available to help protect against this pervasive virus.
Understanding Respiratory Syncytial Virus (RSV)
RSV is a contagious virus that infects the lungs and breathing passages. Symptoms typically appear within four to six days after exposure and can include a runny nose, cough, low-grade fever, sore throat, sneezing, and headache. While most people experience mild illness and recover within one to two weeks, RSV can lead to more serious conditions like bronchiolitis and pneumonia, especially in certain populations.
Infants, particularly those younger than six months, and older adults are at increased risk for severe RSV disease. Young infants may exhibit irritability, decreased activity, or breathing difficulties. Each year, RSV causes tens of thousands of hospitalizations among young children and older adults in the United States. RSV infections typically follow a seasonal pattern, with outbreaks most common during the fall and winter months.
The Recent Arrival of RSV Vaccines
The U.S. Food and Drug Administration (FDA) approved the first RSV vaccines and preventative antibodies in 2023, marking a significant advancement. Arexvy (GSK) was the first RSV vaccine approved for individuals 60 years of age and older in May 2023.
Following Arexvy’s approval, Abrysvo (Pfizer) received FDA approval in May 2023 for adults 60 years and older. Abrysvo also gained approval in August 2023 for pregnant individuals to protect their infants from birth through six months of age. For direct protection of infants, Beyfortus (nirsevimab), a monoclonal antibody, was approved by the FDA in July 2023.
How RSV Vaccines Work
The new RSV preventative measures utilize different scientific approaches. Vaccines for older adults and pregnant individuals stimulate the body’s immune system to produce antibodies. These vaccines often target the prefusion F protein of the RSV virus, which is crucial for the virus to infect cells, prompting a strong protective response.
Monoclonal antibodies, such as nirsevimab (Beyfortus), provide passive protection. These laboratory-made antibodies are directly given to the individual, offering immediate defense against the virus. This approach is particularly beneficial for infants, whose immune systems are still developing.
Who is Recommended for RSV Vaccination?
Health authorities, such as the Centers for Disease Control and Prevention (CDC) and its Advisory Committee on Immunization Practices (ACIP), have issued specific recommendations for RSV prevention. Older adults aged 60 years and older are a primary target group. All adults aged 75 and older are recommended to receive a single dose of an RSV vaccine, as are adults aged 60 to 74 years with increased risk for severe RSV disease.
Pregnant individuals are recommended to receive an RSV vaccine during weeks 32 through 36 of pregnancy. This maternal vaccination transfers protective antibodies to the unborn baby, offering defense against RSV from birth through their first six months of life. For infants, a single dose of nirsevimab (Beyfortus) is recommended for those under eight months old who are born during or entering their first RSV season, especially if not protected by maternal vaccination. Children up to 24 months of age who remain vulnerable to severe RSV disease in their second RSV season may also be candidates.
Safety and Considerations for RSV Vaccination
The new RSV preventative measures have undergone rigorous testing. Common, mild side effects for RSV vaccines include pain, redness, or swelling at the injection site, fatigue, headache, and muscle or joint pain. These reactions are typically temporary and resolve within a few days. For monoclonal antibodies like nirsevimab, injection site reactions and a mild rash are common side effects.
Serious side effects are rare, but have been monitored during clinical trials and post-approval surveillance. Very rare cases of Guillain-Barré syndrome have been reported in some older adults after RSV vaccination, though a causal link is still being evaluated. Pregnant individuals receiving the vaccine have also been monitored for potential risks such as preterm birth, with ongoing studies to assess any causal relationship. Individuals should discuss their personal health history and any concerns with their healthcare provider regarding RSV prevention.