BACKGROUND AND OBJECTIVES: Many neonatal intensive care units (NICUs) do not give rotavirus vaccines to inpatients due to a theoretical risk of horizontal transmission of vaccine strains. We aimed to determine incidence and clinical significance of vaccine-strain transmission to unvaccinated infants in a NICU that routinely administers pentavalent rotavirus vaccine (RV5). METHODS: This prospective cohort study included all patients admitted to a 100-bed NICU for 1 year. Stool specimens were collected weekly; real-time quantitative reverse-transcription polymerase chain reaction was used to detect any RV5 strain. Incidence of transmission to unvaccinated infants was calculated assuming each unvaccinated patient's stool contributed 1 patient-day at risk for transmission. Investigations and geospatial analyses were conducted for suspected transmission events. RESULTS: Of 1238 infants admitted, 560 (45%) were premature and 322 (26%) had gastrointestinal pathology. During observation, 226 RV5 doses were administered. Overall, 3448 stool samples were tested, including 2252 from 686 unvaccinated patients. Most (681, 99.3%) unvaccinated patients never tested positive for RV5 strain. Five (<1%) tested RV5 strain positive. The estimated rate of transmission to unvaccinated infants was 5/2252 stools or 2.2/1000 patient-days at risk (95% CI: 0.7-5.2). No gastroenteritis symptoms were identified in transmission cases within 7 days of collection of RV5-positive stool. Of 126 patients for whom the RV5 series was initiated before the discharge date, 55% would have become age-ineligible to start the series if vaccination was allowed only at discharge. CONCLUSIONS: Transmission of RV5 strain was infrequent and without clinical consequences. Benefits of allowing vaccine-induced protection against rotavirus disease in infants through in-NICU RV5 vaccination appear to have outweighed risks from vaccine-strain transmission.

Hepatitis C virus (HCV) infections are public health problem across the globe, particularly in developing countries. Pakistan has the second highest prevalence of HCV infection worldwide. Limited data exist from Pakistan about persons who inject drugs (PWID) and are at significant risk of exposure to HCV infection and transmission. Serum specimens (n = 110) collected from PWID residing in four provinces were tested for molecular markers of HCV infection. Next generation sequencing (NGS) of the hypervariable region (HVR1) of HCV and Global Hepatitis Outbreak and Surveillance Technology (GHOST) were used to determine HCV genotype, genetic heterogeneity, and construct transmission networks. Among tested specimens, 47.3% were found anti-HCV positive and 34.6% were HCV RNA-positive and belonged to four genotypes, with 3a most prevalent followed by 1a, 1b and 4a. Variants sampled from five cases formed phylogenetic cluster and a transmission network. One case harbored infection with two different genotypes. High prevalence of infections and presence of various genotypes indicate frequent introduction and transmission of HCV among PWID in Pakistan. Identification of a transmission cluster across three provinces, involving 20% of all cases, suggests the existence of a countrywide transmission network among PWIDs. Understanding the structure of this network should assist in devising effective public health strategies to eliminate HCV infection in Pakistan.

Many kindergarten through grade 12 (K-12) schools offering in-person learning have adopted strategies to limit the spread of SARS-CoV-2, the virus that causes COVID-19 (1). These measures include mandating use of face masks, physical distancing in classrooms, increasing ventilation with outdoor air, identification of close contacts,* and following CDC isolation and quarantine guidance(†) (2). A 2-week pilot investigation was conducted to investigate occurrences of SARS-CoV-2 secondary transmission in K-12 schools in the city of Springfield, Missouri, and in St. Louis County, Missouri, during December 7-18, 2020. Schools in both locations implemented COVID-19 mitigation strategies; however, Springfield implemented a modified quarantine policy permitting student close contacts aged ≤18 years who had school-associated contact with a person with COVID-19 and met masking requirements during their exposure to continue in-person learning.(§) Participating students, teachers, and staff members with COVID-19 (37) from 22 schools and their school-based close contacts (contacts) (156) were interviewed, and contacts were offered SARS-CoV-2 testing. Among 102 school-based contacts who received testing, two (2%) had positive test results indicating probable school-based SARS-CoV-2 secondary transmission. Both contacts were in Springfield and did not meet criteria to participate in the modified quarantine. In Springfield, 42 student contacts were permitted to continue in-person learning under the modified quarantine; among the 30 who were interviewed, 21 were tested, and none received a positive test result. Despite high community transmission, SARS-CoV-2 transmission in schools implementing COVID-19 mitigation strategies was lower than that in the community. Until additional data are available, K-12 schools should continue implementing CDC-recommended mitigation measures (2) and follow CDC isolation and quarantine guidance to minimize secondary transmission in schools offering in-person learning.