Optimized infection control practices augment the robust protective effect of vaccination for ESRD patients during a hemodialysis facility SARS-CoV-2 outbreak

Abstract

Background: While dialysis patients are at greater risk of serious SARS-CoV-2 complications, stringent infection prevention measures can help mitigate infection and transmission risks within dialysis facilities. We describe an outbreak of 14 cases diagnosed in a hospital-based outpatient ESRD facility over 13 days in the second quarter of 2021, and our coordinated use of epidemiology, viral genome sequencing, and infection control practices to quickly end the transmission cycle.

Methods: Symptomatic patients and staff members were diagnosed by RT-PCR. Facility-wide screening utilized SARS-CoV-2 antigen tests. SARS-CoV-2 genome sequences were obtained from residual diagnostic specimens.

Results: Of the 106 patients receiving dialysis in the facility, 10 were diagnosed with SARS-CoV-2 infection, as was 1 patient support person. Of 3 positive staff members, 2 were unvaccinated and had provided care for 6 and 4 of the affected patients, respectively. Sequencing demonstrated that all cases in the cluster shared an identical B.1.1.7./Alpha substrain. Attack rates were greatest among unvaccinated patients and staff. Vaccine effectiveness was 88% among patients.

Conclusions: Prompt recognition of an infection cluster and rapid intervention efforts successfully ended the outbreak. Alongside consistent adherence to core infection prevention measures, vaccination was highly effective in reducing disease incidence and morbidity in this vulnerable population.

Keywords: COVID19; Genomics; Nosocomial transmission; Viral epidemiology.

Fig 1

Outbreak timeline and phylogenetic tree of viral genomes. (A) Cases are identified by an ID (P = Patient, S = Staff), and color-coded by which of 2 non-overlapping dialysis schedules was utilized by patients (Blue = A, Red = B). Staff cases are indicated in Green. (B) Excerpt of the B.1.1.7 clade from our phylogenetic tree showing the outbreak strain, which was distinguished by 2 sequence variants from other cases we had sequenced. Specimens aligned vertically are genetically identical.