Grant: Project Grant

More than 1 in 200 babies in North America are born with congenital cytomegalovirus infection (cCMV). Of those infants, ~20% will develop permanent neurologic problems - cCMV causes 13-40% of all childhood hearing loss, and is second only to Down syndrome among causes of intellectual disability. Most newborns with cCMV (90-99%) have either no symptoms or very mild, non-specific symptoms, and for that reason very few cases of cCMV are diagnosed in infancy. Missed cases are important because even those with no symptoms at birth still have a high risk of complications such as hearing loss later in life. There is good evidence that these children's development can be optimized through early interventions (antiviral treatment, hearing monitoring and early use of hearing aids, and speech therapy). For these reasons, universal cCMV screening has been predicted to be both beneficial and cost-effective. Newborn Screening Ontario will introduce an expanded Infant Hearing Program in 2018 to diagnose children at risk of hearing loss by testing all babies for 2 things: genes that cause hearing loss, and cCMV. This will be Canada's first, and the world's largest, universal newborn CMV screening program, using dried blood spots (DBS) collected at birth for metabolic disease screening. Despite the benefits expected, questions remain about how to best implement this program. While sensitivity of CMV testing using DBS has been estimated at up to 85%, sensitivity of CMV testing from saliva approaches 100%; however it requires collecting saliva in addition to DBS. We plan to do CMV testing for 30,000 babies from both DBS and saliva samples to determine the optimal approach. This will involve two aims: 1. Compare the actual sensitivity of DBS versus saliva (we predict 10-20% improved sensitivity using saliva), including for both asymptomatic and symptomatic cases. 2. Determine real-world cost-effectiveness of each cCMV diagnosis approach to inform program implementation.