Community RSV Surveillance in the Long‐Acting Monoclonal Antibody Era

The highest rates of respiratory syncytial virus (RSV) lower respiratory tract infection and hospitalisation occur in the first 6 months of life, with disproportionate burden in preterm infants and in those with cardiopulmonary disease and other at-risk conditions [1]. In temperate settings, this translated into an annual peak in emergency presentations and admissions, driven by bronchiolitis and poor feeding, with a broad downstream impact on service capacity and families [2]. For many years, palivizumab was the only available RSV immunoprophylaxis [3]. Although moderately effective, the need for monthly dosing, the complexity of delivery and the associated cost largely restricted its use to selected high-risk infants [3]. The RSV prevention landscape has now shifted. RSV vaccines are now available during pregnancy and in older adults [4]. However, active vaccination in early infancy remains unavailable due to the risk of vaccine-associated enhanced respiratory disease, first observed with formalin-inactivated vaccine candidates and again emerging as a safety signal in recent paediatric mRNA vaccine studies [5]. In contrast, long-acting monoclonal antibodies have made single-dose, season-long infant protection feasible [3]. Two products are now available, nirsevimab and clesrovimab, with nirsevimab introduced in Europe and Australia in 2024 [3]. Real-world effectiveness data for nirsevimab are now widely available [6, 7]. Australian data estimated an 88% effectiveness against RSV-associated acute respiratory infection hospitalisations, consistent with international reports [6, 7]. Community-level data, however, remain comparatively sparse. The report by El-Heneidy et al. used laboratory network data to examine the association between the rollout of nirsevimab in Queensland and RSV detections in the community [8]. As laboratory testing and detections are influenced by clinical practice and the circulation of other respiratory pathogens, the authors incorporated an older comparator group to account for time-varying confounding. Following program introduction in mid-April 2024, RSV test positivity declined by almost 7 percentage points among nirsevimab-eligible infants aged ≤ 3 months. Although the absence of linked immunisation data limits individual-level causal inference, the pattern provides a strong community signal supporting nirsevimab-based prevention beyond hospital-centred endpoints. Laboratory data will continue to anchor monitoring as immunisation programs mature, with susceptibility surveillance becoming increasingly relevant as nersivimab use expands [9]. Durable nersivimab effectiveness depends on virologic stability under increasing selection pressure [3]. Reduced susceptibility has emerged with other RSV monoclonal antibodies [3] while a clinically significant loss of susceptibility has not been demonstrated for nirsevimab to date [9]. Sequencing of clinical samples, complemented by wastewater programs, will strengthen surveillance and provide an early indication of changes that may undermine effectiveness [9]. Taken together, these data support nirsevimab as a practical population strategy to protect young infants and show that routine laboratory surveillance can quantify community impact, guiding program refinement as uptake expands and benefits accrue over the coming seasons. The author has nothing to report. The author declares no conflicts of interest. Data sharing not applicable to this article as no datasets were generated or analysed during the current study.