Searching for immune correlates in Lassa vaccine development – workshop report

The first workshop dedicated to Lassa virus-specific correlates of protection (CoP) was held in 2024 and was convened by the Coalition for Epidemic Preparedness Innovations (CEPI).Experts from multiple disciplines reviewed existing knowledge and identified gaps in understanding Lassa virusand vaccine-induced immune responses.Discussions covered key areas including epidemiology, immunogenicity, preclinical and clinical research, data science, and regulatory considerations, with the goal of pinpointing opportunities to discover CoP. Importance of Lassa virus-specific immune correlate of protection (CoP)Lassa fever (LF) is a major public health issue in endemic areas of West Africa, causing 100,000-300,000 infection and approximately 5000 deaths yearly 1,2 .These estimates remain imprecise, as disease surveillance is not conducted consistently or uniformly across settings 3 .LF is an acute hemorrhagic fever caused by Lassa virus (LASV), first isolated in Nigeria in 1969 4,5 .The main reservoir is the peri-domestic rodent, Mastomys natalensis 6 .LF is often undiagnosed and symptoms are highly unspecific, mimicking those of other common endemic illnesses including malaria.Among symptomatic infections, 15-20% are severe, with older age and pregnancy associated with increased risk 7,8 .One important sequalae from LASV-infection is hearing loss.There are currently no approved therapeutics or vaccines; all drugs used to treat LF are off-label, thus emphasizing the importance of a vaccine.Vaccine development has been identified as a priority by the World Health Organization (WHO) 9,10 and CEPI.