Background

While licensed COVID-19 vaccines are highly efficacious at reducing severe disease for the majority of vaccinated individuals, there remains an unmet need to reduce SARS-CoV-2 transmission, particularly in children who are typically asymptomatic carriers, and in the elderly, who are susceptible to outbreaks in aged care facilities and severe disease.

SARS-CoV-2 immune imprinting - the tendency for a novel SARS-CoV-2 variant to stimulate memory B cells to produce antibodies against a previously encountered viral (or vaccine) strain - can lead to a poorer ability to fight SARS-CoV-2 variants such as omicron (BA.5). In today’s heavily-vaccinated or previously-infected population, immune imprinting means SARS-CoV-2 variant-specific vaccines reduce disease severity but not infection and transmission.