Impact of a Statewide Hearing-Targeted Congenital Cytomegalovirus Screening Mandate: An 11-Year Interrupted Time Series Analysis.

Objective: Congenital cytomegalovirus (cCMV) is a leading cause of potentially treatable non-genetic hearing loss, but many cases are missed at birth. In 2016, Connecticut mandated hearing-targeted cCMV screening for all newborns who fail their initial hearing test. We evaluated its impact on diagnosis rates and long-term outcomes by comparing the 3 years of no screening with the subsequent eight years of mandated screening. Methods: We conducted a retrospective interrupted time series study (2013-2023) within a health system serving ~60% of Connecticut's population. Confirmed cases were defined as positive CMV testing within 21 days of life. Annual diagnosis rates were modeled before and after mandate implementation. Long-term audiologic and neurodevelopmental outcomes were tracked through June 2025. Results: Among 197,177 births, 48 infants had confirmed cCMV. The screening mandate was associated with a 3.6-fold increase in diagnoses (IRR 3.58; 95% CI 1.17-11.0), peaking at 4.09 per 10,000 births. Prior to the mandate, all detected cases were moderately to severely symptomatic. Afterward, 11 clinically inapparent cases were identified, 73% of whom were later found to have significant sequelae. Among those with sensorineural hearing loss at birth, 81% worsened over time. Developmental delays occurred in 61% of children with follow-up. Conclusion: Hearing-targeted screening increased cCMV case detection and identified infants with clinically meaningful disease who would otherwise have been missed. However, many infections likely remain undetected, underscoring both the value and limitations of targeted approaches and highlighting the need to consider universal screening.