Mandatory hearing checks for newborns helped clinicians catch four times as many cases of the most common congenital infection. However, the screening system still missed a large proportion of infected infants based on estimated disease prevalence.

The time-series study, published in Pediatrics, strengthens the case for universal screening of congenital cytomegalovirus (cCMV), the authors of an accompanying editorial argued.

“Many children are still missed, especially those who look well early on,” said Aanchal Wats, MD, MPH, postdoctoral associate in pediatric infectious diseases at the Yale School of Medicine in New Haven, Connecticut, who led the study. “We were able to identify infants with milder disease or isolated hearing loss who might otherwise not have been diagnosed.”

cCMV affects hearing but can also lead to behavioral, intellectual, and linguistic complications and is frequently asymptomatic and underdiagnosed. Approximately 16,000 infants are infected annually, with nearly 20% developing related long-term effects such as cerebral palsy, intellectual disability, and vision loss.

Wats and colleagues evaluated the effects of Connecticut’s 2016 law requiring cCMV testing of infants who failed newborn hearing screening to determine whether the policy improved diagnosis and long-term outcomes for these infants.

Prior to the law, clinicians tested infants on a case-by-case basis. Starting in January 2016, clinicians were required to test newborns who did not pass a hearing screening for cCMV via saliva or urine. Positive cases were referred for additional testing, such as bloodwork, head ultrasound, ophthalmologic assessment, and audiologic assessment. Clinicians also continued to test newborns based on clinical suspicion alone.

Investigators analyzed data from nearly 200,000 births within the Yale New Haven Health System between 2013 and 2023, finding 49 confirmed or probable cases of cCMV (45% girls and 47% White). The new screening process led to more than a fourfold increase in diagnoses, from 1.1 per 10,000 births before the law to 4.2 cases immediately after, holding steady until a drop during COVID pandemic.

Before implementation, all diagnosed infants were symptomatic. After implementation, 28% of those diagnosed were asymptomatic or had isolated sensorineural hearing loss.

Almost half of the infected patients passed the initial screening but were referred for testing on the basis of clinician judgment, or their cCMV test was ordered before the hearing results arrived.

“The screening mandate likely raised awareness among clinicians and made cCMV part of the conversation when an infant had concerning findings or a maternal cCMV history,” Wats said.

Among diagnosed infants who initially appeared asymptomatic or had isolated hearing loss, 75% later developed neurodevelopmental complications.

“While hearing-targeted cCMV screening can identify some newborns with mildly symptomatic disease, it falls short of fully recognizing the spectrum of children who would benefit from both an earlier referral to receive developmental services and potentially the administration of antiviral treatment,” wrote Sallie R. Permar, MD, PhD, of the Department of Pediatrics at Weill Cornell Medicine in New York City, and colleagues in an accompanying editorial.

The 4.2 per 10,000 births diagnosis rate remained below Connecticut’s estimated prevalence of about 45 infections per 10,000 births.

“Hearing-targeted screening alone will still miss infants with congenital CMV who have less apparent or asymptomatic infection,” said Leena Mithal, MD, MSCI, attending physician in the Division of Infectious Diseases at Ann & Robert H. Lurie Children’s Hospital of Chicago in Chicago, who was not associated with the study.

The American Academy of Otolaryngology-Head and Neck Surgery and the American Academy of Audiology recommend universal screening. Mithal said doing so would identify many more affected infants during the critical time after birth and give clinicians the opportunity to monitor and intervene.

“To successfully implement hearing-targeted screening policies, hospital systems need to educate providers and establish clear protocols for cCMV testing and follow-up,” Mithal said.

The sources in this article reported no disclosures or conflicts of interest.

Brittany Vargas is a journalist covering medicine, mental health, and wellness.