Bronchiolitis is already experiencing its first winter with the ‘vaccine’ against RSV

Respiratory syncytial virus (RSV) was discovered in 1956 and a year later was implicated as the main cause of bronchiolitis. Globally, it is the second cause of death in the world in children under one year of age, after malaria – the vast majority occurs in low- and middle-income countries. In Spain there is active surveillance of infections, but this year a “vaccine” has come into play that promises to change the epidemiology of the virus in our country. RSV is the main cause of lower respiratory tract infections in children under one year of age, including bronchiolitis and pneumonia. Also important in adults over 65 years of age and in people with risk conditions. It is known that between 60 and 70% of bronchiolitis cases are due to this virus, although there are others that can also cause bronchiolitis (rhinovirus, metapneumovirus, adenovirus, bocavirus…). Related News standard No Flu and covid epidemic: 10 essential tips from nurses to avoid contagion ABC Health The peak of infections is expected to arrive after the Three Kings holiday Most infants with RSV infection will only have mild symptoms and a cold-like illness that resolves quickly. Sometimes, after three or four days of runny nose and cough, it can cause difficulty breathing and wheezing, low-grade fever, loss of appetite, vomiting with mucus, and difficulty eating. 50% of newborns with serious illness are younger than 3 months. Most of them are previously healthy, so it is unpredictable which neonates will develop serious cases. Older people are also affected by this infection. They are at higher risk of severity due to immunosenescence (aging of the immune system) and other diseases. In addition, it can worsen other pathologies, such as chronic obstructive pulmonary disease (COPD), asthma or heart failure. It will also cause serious complications, such as pneumonia, hospitalization, and even death. Globally, there are an estimated 787,000 hospitalizations and 47,000 deaths related to RSV annually in high-income countries alone. Furthermore, it should be noted that RSV infection has been linked to recurrent wheezing, bronchial asthma, and other long-term sequelae. Why is this year different? As in many viral infections, treatment is only symptomatic. That is, aimed at reducing symptoms (management of secretions, oxygen therapy, hydration and adequate nutrition, etc.). Antibiotics, cough syrups or mucolytics do not work. In severe cases, resort to supportive therapy. Until now, measures to prevent this infection focused on those available for any other respiratory virus, such as frequent hand washing and the use of disposable tissues. Also avoid adults with respiratory infections near the child, avoid tobacco smoke and crowded environments. After many years of research, for the first time, we have measures with a direct impact on the incidence of this disease. While during the 2022/23 season the term “tripledemia” became popular – in reference to the simultaneous circulation of RSV, flu and covid-19 -, in this season we have achieved an 83% reduction in hospitalizations due to RSV in neonatology, and 50% due to other respiratory infections (pneumococcal infections, otitis media, etc.). This is due to the popularly called “RSV vaccine” for children. It is actually not a vaccine, but a “monoclonal antibody” called nirsevimab (Beyfortus). These types of therapies are known as passive immunization. They provide faster protection, since the antibody against the pathogen is administered directly to the baby, without having to wait for the baby to generate it himself in response to a vaccine. Nirsevimab was approved by the European body responsible for regulating this type of medicine, the European Medicines Agency (EMA), on November 4, 2022. Its approval derives from the efficacy and safety results of two clinical trials: Phase IIb and Phase II I (MELODY) for prevention in full-term and preterm infants exposed to their first season of RSV. Studies showed that a single dose maintains adequate protective levels. Thus, it reduces conditions requiring medical attention and hospitalization by 76%, and infections by 78%, in the 150 days following its administration. In our country it is indicated for the prevention of lower respiratory tract disease caused by RSV in neonates and infants during their first RSV season. As of now, it is not approved for adults. Spanish Association of Pediatrics. Vaccine Advisory Committee. What results have we seen after its implementation? Nirsevimab began administration in late September 2023 and overall adherence has been very favorable. On those dates, in the majority of Spanish Autonomous Communities (following the guidelines of the Ministry of Health) very powerful campaigns and a very ambitious immunization schedule were carried out, which was very well received by the parents of children who met the criteria to receive . the drug. Spain is practically a pioneer at an international level and, in view of the results, it should be a source of pride. Coverage is being high this 2023-24 campaign. In Andalusia it exceeds 90% in all age groups. In Galicia it exceeds 85%. This broad coverage has led to a clear decrease in cumulative hospitalization rates in infants who received nirsevimab compared to previous seasons and to infants who did not receive the drug. The decrease has been up to 73% in week 48, the one with the highest hospitalization rate, compared to the average of the same week of the three previous seasons in the pre-covid era in children under 6 months of age (96 cases per 100,000 inhabitants 339 cases per 100,000 inhabitants), and 80% (108 cases per 100,000 inhabitants vs. 515 cases per 100,000 inhabitants) in children under 2 months. An advantage of this molecule is that it has a longer half-life (duration of its effect) than others previously used. This has allowed it to last the entire RSV epidemic season in immunized infants with a single administration. The results observed this year with the introduction of a new medication for the prevention of severe cases of RSV infection have been very positive. They have meant a sharp and significant drop in hospitalization and mortality, which this virus can cause in younger children. It is therefore necessary to monitor the results it offers in the following epidemic waves, while continuing to invest in science to offer alternatives for this and other vulnerable population groups in case of decreased effectiveness. Article published in La Conversación. Antonio Gutiérrez Pizarraya. Epidemiologist. Health Technology Assessment. Virgin Macarena Hospital. Junta de Andalucía., University of Seville Desktop Code Image for mobile, amp and app Mobile code AMP Code APP Code Elena Salamanca Rivera. Doctor. MD, PhD. Infectious Diseases Service. Virgin Macarena Hospital. Junta de Andalucía., University of Seville