RSV disease—is there a role for prevention?

Abstract

With the advent of widespread vaccination programmes, the majority of viral infections which repeatedly plagued us throughout the 20th century have been greatly reduced or even abolished. However, the morbidity caused by the respiratory syncytial virus (RSV) to the infant, his family and the healthcare services remains virtually unchanged. During the winter months (December to March in the northern hemisphere) epidemics of RSV infections continue to cause major problems in both primary and secondary care, the virus being the leading cause of lower respiratory tract infections in infants and young children (1). Passively acquired maternal antibody, specific to RSV, declines in the first few months of life but by 1 year of age up to 50% of all babies will have been actively infected by RSV. This figure rises to 90% by 3 years of age (2). In the U.K. approximately 20 000 infants are admitted each year with RSV-positive bronchiolitis, which is approximately 3% of all U.K. yearly births. More than 50% of these admissions are between 1 and 3 months of age, causing major staffing and bed problems for all paediatric units. Assuming the main pathophysiological changes caused by the infection are centred around the small airways with release of inflammatory mediators, intense inflammation, oedema of the mucosa and the production of copious secretions, it is not surprising that pharmacological treatment has been disappointing. Although there is still some dispute between clinicians in different countries the consensus view is that in typical infantile RSV-positive acute bronchiolitis there is little or no place for bronchodilators (3) or steroids (4, 5). Some studies using nebulized adrenaline (6, 7) have suggested some improvement, whereas others (8) have not. Opinion on the use of Ribavarin, a synthetic purine nucleotide derivative, remains divided and large multi-centre, randomized, controlled studies are still needed to assess the benefits (9,10). A recent study (11) showed no benefit from inhaled steroids in infants recovering from bronchiolitis. The only agent which is agreed by all to be beneficial in acute bronchiolitis is oxygen to maintain normal blood oxygen saturation (SaO2) levels. It is not only the acute episode of bronchiolitis which is of concern. There are recognized long-term consequences following RSV infection which have recently been extensively reviewed (12). Approximately 50% of infants with RSV lower respiratory tract infections will have recurrent episodes of wheezing during early childhood. Pre-existing lung function defects may also be related to long-term airway morbidity. The recent study by Stein et al. (13), following up a birth cohort for 13 years, was in agreement with the long-term follow-up of babies hospitalized in Nottingham due to acute bronchiolitis (14). Both studies