The Tennessee Department of Health (TDH) identifies infants who have been perinatally exposed to HCV by linking HCV test results to birth certificates. All antibody-positive, RNA-positive, and RNA-negative HCV test results are reportable in Tennessee. Although antibody-negative HCV test results are not reportable, the TDH requests that the infant’s clinician provide these results if antibody testing is performed. For infants born to pregnant persons with hepatitis C from January 1, 2018 to July 31, 2020, we collected select sociodemographic information (eg, race, ethnicity, county, and insurance type) from birth certificate information and linked it with infant HCV test results as of July 31, 2023.

We defined HCV RNA testing at 2 to 36 months of age or antibody testing at 18 to 36 months of age as guideline-adherent to include guideline changes during the study period;^3,4 testing conducted outside these ages was defined as not guideline-adherent. The TDH defines perinatal hepatitis C cases as confirmed if RNA is detected at 2 to 36 months of age, probable if the patient is antibody-reactive from 18 to 36 months of age, and excluded if the patient is RNA-negative at 2 to 36 months of age or antibody-negative before 36 months of age. Counties of residence were categorized as large metropolitan, small or medium metropolitan, and nonmetropolitan.⁷ Sociodemographic factors associated with guideline-adherent testing and case status were descriptively analyzed by using SAS version 9.4 (SAS Institute, Cary, NC) and a 1-sample proportions test was conducted to estimate the undiagnosed perinatal HCV infection number. This activity was reviewed and approved by the TDH Institutional Review Board and the Centers for Disease Control and Prevention.

Among 3020 infants perinatally exposed to HCV, 776 (26%) had guideline-adherent HCV testing, 177 (6%) had testing that was not guideline-adherent, and 2067 (68%) did not have testing reported to the TDH. The proportion of infants with guideline-adherent testing increased during the study period. Infants born to Black or Hispanic persons had lower odds of receiving guideline-adherent testing, compared with white (odds ratio [OR] = 0.33 [95% confidence interval (CI): 0.20–0.53]) or non-Hispanic (OR = 0.27 [95% CI: 0.11–0.68]) persons. Infants had higher odds of receiving guideline-adherent testing if they were born to a person residing in a metropolitan county categorized as small or medium, compared with large (OR = 2.94 [95% CI: 2.32–3.72]), or if public insurance was used at birth, compared with private insurance (OR = 1.64 [95% CI: 1.23–2.18]) (Table 1).

Perinatal hepatitis C case status was determined for 776 infants with guideline-adherent testing and 22 infants with negative antibody test results before 18 months of age. Of 798 infants, 159 (20%) had the earliest results from HCV RNA testing at a median age of 14 months (interquartile range = 6–20 months). The remaining 639 infants (80%) had antibody testing initially at a median age of 20 months (interquartile range = 19–25 months). Among these 798 infants, 51 (6.4% [95% CI: 4.9–8.3]) were classified as having confirmed (n = 45) or probable (n = 6) perinatal hepatitis C. Among these infants, the odds of HCV infection were not statistically different by assessed sociodemographic factors (Table 2). Using a 6% transmission rate, we would expect 181 (95% CI: 157–208) perinatal HCV infections among our total population; therefore, ~130 infants remain undiagnosed.

Despite recommendations that every infant perinatally exposed to HCV be tested, only 26% were tested according to guidelines in Tennessee, although underestimation might have occurred because of voluntary reporting for negative antibody test results. The authors of previous reports have identified similar frequencies of testing.^5,6 Black and Hispanic infants were less frequently tested and, therefore, likely over-represented among infants with undiagnosed HCV infections. With curative HCV treatment recommended for children as young as 3 years,³ children with undiagnosed infections might be less likely to receive timely curative treatment and be disproportionately affected by HCV complications.

In addition to the TDH, Eastern Tennessee health departments and the TennCare public insurance program increased clinician outreach during this study period, which might explain why small and medium metropolitan counties and public insurance were associated with increased testing. Recent guidelines emphasizing RNA testing at 2 to 6 months of age might increase testing by facilitating testing when infants frequently access health care (eg, well-child visits).^4,8 Systemic processes to improve testing are also needed, such as electronic medical record prompts. Equitable implementation of these measures is necessary to avoid compounding racial and ethnic disparities in pediatric HCV diagnosis and treatment.