SGS unveils RSV A-strain challenge agent for vaccine research
SGS has launched a novel Respiratory Syncytial Virus (RSV) A-strain challenge agent designed to accelerate clinical validation of RSV vaccines and therapeutics through controlled human infection models (CHIM).
The fully-validated, GMP-manufactured RSV-NICA challenge agent is derived from an A-strain isolated in 2015, making it more recent than commonly used strains and better representative of currently circulating RSV viruses. The agent demonstrates enhanced ability to reproduce natural infection symptoms, a critical requirement for high-quality CHIM studies.
Proof-of-concept study achieves 100% attack rate
In October 2025, SGS conducted a proof-of-concept study at its Clinical Pharmacology Unit in Antwerp, Belgium, inoculating 12 healthy participants with the RSV A-strain challenge agent. Participants remained in a controlled quarantine environment for 11 days post-inoculation, during which standardised daily assessments of solicited symptoms and nasal swabs for qPCR and viral culture were performed. One participant was excluded from analysis due to a confirmed rhinovirus co-infection. Among the remaining 11 participants, nine developed clinically relevant symptoms and all demonstrated RSV detection by qPCR confirmed by viral culture, resulting in a 100% attack rate.
The study validates the current inoculation titre as suitable for CHIM use. The observed potency of the RSV-NICA agent suggests that dose titration may be feasible without compromising statistical power, enabling optimisation for future challenge studies.
Addressing a significant disease burden
RSV causes an estimated 64 million infections and 3 million hospitalisations annually worldwide, representing one of the leading causes of severe respiratory infections in infants, immunocompromised adults and the elderly. The development of effective vaccines and therapeutics remains a priority for health systems facing yearly RSV outbreaks.
Jelle Klein, Medical Director at SGS, said: “As a leading European partner in infectious disease and vaccine research, we are delighted to have fulfilled our ambition to accelerate the route to clinical validation of novel RSV therapies and vaccines, bridging preclinical insights to human data through the development of this RSV-A strain challenge agent, the first of its kind worldwide.”
Klein added: “There is an urgent need to ensure that vaccines and therapeutics remain effective, available and affordable for patients. Today’s announcement reinforces SGS’s position as a trusted partner, delivering high-quality, decision-enabling data for both pharma-ceutical and biotech companies in their pursuit of effective RSV treatment and prevention.”
Expanding CHIM portfolio in Europe
With the addition of RSV, SGS now offers one of the most comprehensive CHIM portfolios in Europe, including influenza, rhinovirus, malaria and RSV. The company can now support partners in accelerating the development pathway for RSV vaccines and therapeutics.
For more information, visit: www.sgs.com
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