A severe acute respiratory coronavirus virus 2 (SARS-CoV-2) nosocomial cluster with inter-facility spread: Lessons learned

BACKGROUND

Despite infection control guidance, sporadic nosocomial coronavirus disease 2019 (COVID-19) outbreaks occur. We describe a complex severe acute respiratory coronavirus virus 2 (SARS-CoV-2) cluster with interfacility spread during the SARS-CoV-2 δ (delta) pandemic surge in the Midwest.

SETTING

This study was conducted in (1) a hematology-oncology ward in a regional academic medical center and (2) a geographically distant acute rehabilitation hospital.

METHODS

We conducted contact tracing for each COVID-19 case to identify healthcare exposures within 14 days prior to diagnosis. Liberal testing was performed for asymptomatic carriage for patients and staff. Whole-genome sequencing was conducted for all available clinical isolates from patients and healthcare workers (HCWs) to identify transmission clusters.

RESULTS

In the immunosuppressed ward, 19 cases (4 patients, 15 HCWs) shared a genetically related SARS-CoV-2 isolate. Of these 4 patients, 3 died in the hospital or within 1 week of discharge. The suspected index case was a patient with new dyspnea, diagnosed during preprocedure screening. In the rehabilitation hospital, 20 cases (5 patients and 15 HCWs) positive for COVID-19, of whom 2 patients and 3 HCWs had an isolate genetically related to the above cluster. The suspected index case was a patient from the immune suppressed ward whose positive status was not detected at admission to the rehabilitation facility. Our response to this cluster included the following interventions in both settings: restricting visitors, restricting learners, restricting overflow admissions, enforcing strict compliance with escalated PPE, access to on-site free and frequent testing for staff, and testing all patients prior to hospital discharge and transfer to other facilities.

CONCLUSIONS

Stringent infection control measures can prevent nosocomial COVID-19 transmission in healthcare facilities with high-risk patients during pandemic surges. These interventions were successful in ending these outbreaks.

Abstract 3378: Rapid and efficient sample preparations for cell free DNA

The analysis of cell-free DNA (cfDNA) as a sensitive biomarker for cancer prognosis, diagnosis and monitoring resulted in a need for efficient and fast cfDNA isolation. The traditional cfDNA purification methods using chaotropic solvent to separate nucleic acids from plasma through column or magnetic bead purification processes are usually laborious and time consuming, involving multiple washing steps, and the residual organic solvent could be carried over to the elution solution that could cause downstream PCR inhibition. Herein, we developed a novel particle surface chemistry that can biochemically bind rapidly (<1min) and release nucleic acids rapidly (<1min) under different buffer conditions without needing chaotropic solvent. We further optimized the binding and elution buffer solutions that allow to isolate cfDNA from plasma within 5-10 minutes in the sample volumes from 1 ml to 4 ml. The real-time quantitative PCR indicated DNA extraction yields were comparable or slightly better than the traditional methods for both small and large volumes. The novel bead chemistry and the optimized binding and elution buffers are not only compatible to high throughput format but could also be applied to a variety sample types for rapid sample preparations.

Citation Format: Zhiyang Zeng, Andrew Taft, Kasen Riemersma, Connor Fitzgerald, Mike Scurria, Spenccer Hermanson, Wenhui Zhou. Rapid and efficient sample preparations for cell free DNA [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3378.

Gain without pain: Adaptation and increased virulence of Zika virus in vertebrate host without fitness cost in mosquito vector

Zika virus (ZIKV) is now in a post-pandemic period, for which the potential for re-emergence and future spread is unknown. Adding to this uncertainty is the unique capacity of ZIKV to directly transmit between humans via sexual transmission. Recently, we demonstrated that direct transmission of ZIKV between vertebrate hosts leads to rapid adaptation resulting in enhanced virulence in mice and the emergence of three amino acid substitutions (NS2A-A117V, NS2A-A117T, and NS4A-E19G) shared among all vertebrate-passaged lineages. Here, we further characterized these host-adapted viruses and found that vertebrate-passaged viruses also have enhanced transmission potential in mosquitoes. To understand the contribution of genetic changes to the enhanced virulence and transmission phenotype, we engineered these amino acid substitutions, singly and in combination, into a ZIKV infectious clone. We found that NS4A-E19G contributed to the enhanced virulence and mortality phenotype in mice. Further analyses revealed that NS4A-E19G results in increased neurotropism and distinct innate immune signaling patterns in the brain. None of the substitutions contributed to changes in transmission potential in mosquitoes. Together, these findings suggest that direct transmission chains could enable the emergence of more virulent ZIKV strains without compromising mosquito transmission capacity, although the underlying genetics of these adaptations are complex.