Having a scientific tool such as a vaccine to prevent severe cases caused by Respiratory Syncytial Virus (RSV) represents a key advance in health. Immunization reduces the risk of hospitalizations and severe cases, especially in vulnerable individuals.
Although SARS is usually associated with infants and older adults, it can also cause serious symptoms in people under 60 with underlying conditions. The approval of the vaccine for this group aims to reduce hospitalizations and respiratory complications.
A broader respiratory threat than previously thought
Respiratory syncytial virus (RSV) is one of the main causes of respiratory infections in infants and older adults. However, recent studies show that it also poses a risk to adults under 60 with chronic diseases such as asthma, diabetes, heart conditions, or immunosuppression.
Until now, the vaccination strategy covered pregnant women and people over 60. But recently, the National Administration of Medicines, Food, and Medical Technology (ANMAT) approved the use of this vaccine for people aged 18 to 59 with risk factors, which expands preventive coverage against a virus that had been underestimated in this group.
The perception of RSV as a virus exclusive to children or the elderly has historically limited its surveillance in adults. However, evidence accumulated in recent years shows that the lack of lasting immunity after natural infection leads to frequent reinfections in adulthood, and that symptoms can be more severe in people with compromised health.
"In a context where acute respiratory infections are on the rise, highlighting the impact of RSV in young adults with underlying conditions is key to improving diagnosis, prevention, and clinical management," said Dr. Miriam Rozenek (MN. 75.773), an infectious disease specialist and geriatrician, member of the Vaccine Commission of the Argentine Society of Infectious Diseases (SADI), and director of the Infectious Diseases and Geriatrics Council of the Argentine Society of Gerontology and Geriatrics (SAGG).
Hospitalizations and severe cases in people with comorbidities
A study conducted in Mexico recorded a hospitalization rate of 53.3% in adults infected with RSV in the 18-59 age group, with levels of intensive care admissions, mechanical ventilation use, and mortality comparable to those observed in infections such as influenza or COVID-19.
In other Latin American countries, hospitalization for RSV-associated pneumonia in adults reached 91.7% and ranged from 40.9% to 69.9% in those with flu-like symptoms. These data reinforce the need to include people with comorbidities in prevention policies.
In Argentina, the National Health Surveillance System reported a sustained increase in RSV detections since epidemiological week 12 of 2025, reaching 295 reported cases in weeks 18 and 19, indicating an upward trend.
Symptoms of RSV
Respiratory syncytial virus (RSV) infection usually begins with upper respiratory symptoms such as a runny nose, congestion, cough, and sneezing.
However, in some cases, the condition spreads to the lower respiratory tract, where it can cause obstruction of the bronchioles and lead to severe complications such as pneumonia, respiratory distress, episodes of apnea, and even fatal outcomes.
Transmission occurs through droplets that are dispersed in the air when talking, coughing, or sneezing, which facilitates its spread between people.
Who is at risk from RSV?
Advanced age is one of the best-known factors, but it is not the only one. Underlying conditions that increase the risk of RSV complications include:
- Chronic lung diseases (asthma, COPD)
- Cardiovascular diseases (heart failure, coronary artery disease)
- Immunosuppression states (cancer, transplants, immunosuppressive treatments)
- Diabetes mellitus
- Liver, kidney, or neuromuscular diseases
"The viral load of RSV is usually lower in adults than in children, which makes it difficult to detect without using molecular tests such as RT-PCR," explained Rozenek.
According to Rozenek, the main problem is underdiagnosis: "In the adult population, RSV symptoms are more nonspecific, which can be confused with other respiratory infections."
Vaccination: a new group added
The Pfizer RSV vaccine is a recombinant protein subunit formulation that has been used in pregnant women and the elderly. The recent approval by ANMAT authorizes its use in adults between 18 and 59 years of age with underlying conditions, consolidating a broader preventive approach.
"Until now, vaccination has focused almost exclusively on the extremes of life, but we know that many young people with comorbidities can also develop severe forms of the disease," Rozenek said.
The approval was based on the results of the MONeT study, a Phase III clinical trial that evaluated the safety, tolerability, and immunogenicity of the vaccine in adults with chronic diseases.
A robust immune response was observed against RSV-A and RSV-B subtypes, with even higher antibody levels in this age group than in adults over 60 years of age.
The adverse effects reported were mild to moderate, such as pain at the injection site, fever, or fatigue, with no serious events associated with the vaccine.
"Vaccination in vulnerable adults not only protects the individual patient, but also alleviates pressure on health services, as these patients often require more resources: prolonged hospitalization, diagnostic tests, and respiratory support," Rozenek explained.
