2024 Public Health Laboratory Annual Report 
Tracking How Well cCMV Screening is Working

In early 2022, Minnesota became the first state to add Congenital Cytomegalovirus (cCMV) to its newborn screening panel, the list of medical conditions screened for at birth. Since then, thousands of Minnesota newborns have been screened for cCMV, and more than 100 have been diagnosed with the infection.

Being the first to screen for a condition carries extra responsibility. A program must devise both a procedure for testing newborns for the condition and a system for working with health care providers to provide treatments and follow-up. The Minnesota Newborn Screening Program worked hard to arrange both before screening for cCMV began in early 2023. (For more information about initiating cCMV screening, see the article in last year’s Annual Report, Minnesota is the First in the Nation to Screen all Newborns for cCMV.)

To test the effectiveness of its system, the Minnesota Newborn Screening Program has been tracking how well the blood test identifies cases of cCMV and, when a family gets a positive result, how often are they get the recommended follow-up. These questions must be answered before other states can emulate Minnesota’s program and begin screening their newborns for cCMV.

Effectiveness of Tests for cCMV

As with most conditions on the Minnesota Newborn Screening Panel, tests for cCMV involve analyzing blood samples taken from babies soon after birth. However, cCMV is unique in that it is an infectious disease, not a genetic one. It is “congenital” in that it is passed from mother to child through the placenta. This makes it more difficult to detect in a blood sample than a disease with well-defined genetic markers.

Before beginning screening for cCMV, the Minnesota Newborn Screening Program collaborated with the University of Minnesota and the Centers for Disease Control and Prevention (CDC) to produce a study on the effectiveness, or “sensitivity,” of available blood tests for the disease. The result suggested that around 75% of cCMV cases would be flagged by the tests then available. This is a low rate; most newborn screening identifies 99% of cases. 

The Newborn Screening Program is constantly working to improve cCMV tests, but gauging sensitivity was difficult. It needed data of “false negatives,” the cases of babies who had the disease but were not identified by screening. It asked health care providers to report any such cases, but only three were found in more than a year, likely a significant undercount.

Recently, cCMV was added to the Communicable Disease Rule. Health care providers, laboratories, and other mandated reporters must now inform the Minnesota Department of Health of every case involving cCMV. Much of the data will now come automatically through electronic lab reporting. This promises to greatly improve the quality of data needed to fine-tune testing procedures.

Tracking Health Outcomes for Newborns with cCMV Diagnoses

Around 20% of children diagnosed with cCMV will develop hearing loss or other symptoms. At this writing, 11 babies who have been screened and tested positive for cCMV have permanent hearing loss. That number will surely rise, as this represents just one year’s worth of data and symptoms from cCMV can develop up to 6 years after birth. 

It is vital to closely monitor each child who has been diagnosed with cCMV. The standard follow-up is substantial, entailing three evaluations: audiology, ophthalmology, and imaging of the head.

An estimated 75% of the babies diagnosed with cCMV in Minnesota have received all three standard follow-up appointments. The rest tend to come from economically disadvantaged families.

Longitudinal follow-up will be critical for assessing the effectiveness of cCMV screening. It will be years before conclusions can be made. The Minnesota Newborn Screening Program is investing tremendous time and effort in creating the best possible screening program for cCMV, both for the benefit of Minnesotan children and for the children of all states who adopt its procedures in the future.

Return to the main 2024 Annual Report page.