CASCADIA: A prospective community-based study protocol for assessing SARS-CoV-2 vaccine effectiveness in children and adults utilizing a remote nasal swab collection and web-based survey design (preprint)

ABSTRACT

Introduction: Although SARS-CoV-2 vaccines were first approved under Emergency Use Authorization by the FDA in late 2020 for adults, approval for young children 6 months to < 5 years of age did not occur until 2022. Understanding real world vaccine effectiveness in the setting of emerging variants is critical. The primary goal of this study is to evaluate SARS-CoV-2 vaccine effectiveness (VE) against infection among children aged >6 months and adults aged <50 years. Methods: CASCADIA is a four-year community-based prospective study of SARS-CoV-2 VE among adult and pediatric populations aged 6 months to 49 years in Oregon and Washington. At enrollment and regular intervals, participants complete a sociodemographic questionnaire. Individuals may provide a blood sample at enrollment and annually thereafter, with additional, optional blood draws after infection and vaccination. Participants complete weekly self-collection of anterior nasal swabs and symptom questionnaires. Swabs are tested for SARS-CoV-2 and other respiratory pathogens by RT-PCR, with results of selected pathogens returned to participants; nasal swabs with SARS-CoV-2 detected will undergo whole genome sequencing. Participants who report symptoms outside of their weekly swab collection and symptom survey are asked to collect an additional swab. Participants who test positive for SARS-CoV-2 undergo serial swab collection every three days for three weeks. Serum samples are tested for SARS-CoV-2 antibody by binding and neutralization assays. Analysis: Cox regression models will be used to estimate the hazard ratio associated with SARS-CoV-2 vaccination among the pediatric and adult population, controlling for demographic factors and potential confounders, including clustering within households.