CMV Study Finds Over Half of Infected Newborns Missed Without Universal Screening

A large-scale study conducted by Hadassah Medical Center and the Hebrew University has revealed that over half of newborns with congenital Cytomegalovirus (CMV) would go undiagnosed if screening were limited to infants with suspected exposure or symptoms. The research, published in The Lancet Infectious Diseases, highlights CMV as a leading non-genetic cause of hearing loss and a potential contributor to neurological developmental issues, with complications sometimes appearing later in life.

The challenge lies in the fact that most infected infants appear healthy at birth and pass initial hearing tests. The study, led by Professor Dana Wolf of Hadassah and the Hebrew University, along with Professor Smadar Avnet-Friedman of Hadassah and Professor Moran Yassour of the Hebrew University, examined 48,556 newborns between April 2022 and March 2025, representing nearly 95% of births at Hadassah's Jerusalem hospitals. CMV was diagnosed in 176 infants, approximately 3.6 cases per thousand births.

Under current standard practices, only infants failing hearing tests, showing disease signs, or whose mothers contracted the virus during pregnancy are tested. However, the study found that 100 of the 176 diagnosed infants (57%) met none of these criteria. Among these undiagnosed infants, eight later developed moderate to severe symptoms, three experienced hearing loss despite appearing asymptomatic, and 11 received antiviral treatment.

To enable widespread screening, researchers adapted a "pooling" method, originally developed for COVID-19 PCR testing. Saliva samples from multiple infants were combined and tested; only positive pooled results triggered individual testing, with diagnoses confirmed by urine tests. This pooling technique reduced the number of tests by 83% while maintaining high sensitivity.

Furthermore, the study indicated that prior maternal exposure to CMV does not guarantee immunity, as 53% of infant infections occurred from reinfection rather than primary infection, with similar complication rates in both groups. The researchers concluded that their findings support universal newborn CMV screening, achievable through the cost-effective pooling method. However, they cautioned that the study was limited to two hospitals and did not assess the cost-effectiveness of universal screening, recommending further evaluation before widespread implementation.