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BackgroundWhile dialysis patients are at greater risk of serious SARS-CoV-2 complications, stringent infection prevention measures can help mitigate the risk of infection and transmission within dialysis facilities. We describe an outbreak of 14 cases diagnosed in a 13-day period in the second quarter of 2021 in a hospital-based ESRD facility, and our coordinated use of epidemiology, viral genome sequencing, and infection control practices to quickly end the cycle of transmission.MethodsSymptomatic patients and staff members were diagnosed via RT-PCR tests. Facility-wide screening was conducted using rapid SARS-CoV-2 antigen tests. SARS-CoV-2 genome sequences were obtained from residual diagnostic PCR specimens.ResultsOf the 106 patients who received dialysis in the facility, 10 were diagnosed with SARS-CoV-2 infection, as was one patient support person. Of three positive staff members, two were unvaccinated and had provided care for six and four of the affected patients, respectively. Sequencing demonstrated that all the 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.ConclusionsPrompt 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.

A modified two-tiered testing algorithm (MTTT; ZEUS Scientific) for Borrelia burgdorferi was recently FDA-cleared. We evaluated the MTTT algorithm to confirm Lyme disease and compared the findings in parallel with those obtained using standard two-tiered testing (STTT). Medical records from patients who submitted sera for laboratory confirmation of Lyme-like disease were reviewed. Three hundred twenty patient samples were run by the STTT and MTTT approaches and the results compared. Positive STTT samples were also positive by MTTT (94%). The MTTT confirmed the illness in 116 subjects (36%, P = 0.007), and 30 (26%) were negative by the STTT. Increased MTTT sensitivity was seen (P = 0.0005) during early infection. MTTT was insufficiently sensitive to identify other non-Borrelia spp. infections. Routine adoption of MTTT would improve sensitivity for early Lyme disease attributable to B. burgdorferi, but may not capture illness attributed to B. mayonii and B. miyamotoi.

The implementation of monoclonal antibody therapeutics during the COVID-19 pandemic altered the selective pressures encountered by SARS-CoV-2, raising the possibility of selection for resistant variants. Within-host viral evolution was reported in treated immunocompromised individuals but whether this signifies a real risk of onward transmission is unclear. We used a regional SARS-CoV-2 sequencing program to monitor lineages with clinically relevant variants in identified patients, which facilitated analysis of parameters potentially relevant to new variant emergence. Here we describe a newly acquired spike E484K mutation detected within the B.1.311 lineage. Multiple individuals in two households of the same extended family were infected. The timing and patterns of spread were consistent with de novo emergence of this E484K variant in the bamlanivimab-treated index patient. Our study suggests that the selective pressures introduced by the widespread administration of these antibodies may warrant increased genomic surveillance to identify and mitigate spread of therapy-induced variants.

The implementation of monoclonal antibody therapeutics during the COVID19 pandemic has altered the selective pressures encountered by SARS-CoV-2, raising the possibility of selection for variants resistant to one or more monoclonal antibodies and subsequent transmission into the wider population. Early studies indicated that monoclonal antibody treatment in immunocompromised individuals could result in within-host viral evolution preferentially affecting epitopes recognized by these antibodies, although whether this signifies a real risk of transmissible antibody resistant virus is unclear.In this study we have taken advantage of a regional SARS-CoV-2 genomic surveillance program encompassing regions in Wisconsin, Minnesota and Iowa to monitor the introduction or de novo emergence of SARS-Cov-2 lineages with clinically relevant variants. Here we describe a newly acquired E484K mutation in the SARS-CoV-2 spike protein detected within the B.1.311 lineage. Multiple individuals in two related households were infected. The timing and patterns of subsequent spread were consistent with de novo emergence of this E484K variant in the initially affected individual who had been treated with bamlanivimab monotherapy. The subsequent transmission to close contacts occurred several days after the resolution of symptoms and the end of this patient’s quarantine period. Our study suggests that the selective pressures introduced by the now widespread administration of these antibodies may warrant increased genomic surveillance to identify and mitigate spread of therapy-induced variants.

BackgroundThe COVID-19 pandemic of 2020 poses a particularly high risk for End Stage Renal Disease (ESRD) patients and led to a need for facility-wide control plans to prevent introduction and spread of infection within ESRD facilities. Rapid identification of clusters of contemporaneous cases is essential, as these may be indicative of within-facility spread. Nevertheless, in a setting of high community COVID-19 prevalence, a series of ESRD patients may test positive at around the same time without their shared ESRD facility being the nexus for disease spread. Here we describe a series of five cases occurring within an eleven-day period in November 2020 in a hospital-based 32-station ESRD facility in southwest Wisconsin, the subsequent facility-wide testing, and the use of genetic sequence analysis of positive specimens to evaluate whether these cases were linked.MethodsFour patient cases and one staff case were identified in symptomatic individuals by RT-PCR. Facility-wide screening was initiated at the request of local public health and conducted using Abbot BinaxNOW antigen tests. SARS-CoV-2 genome sequences were obtained from residual diagnostic test specimens using an amplicon-based approach on an Ion Torrent S5 sequencer.ResultsResidual specimens from 4 of 5 cases were available for sequence analysis. Each sequence was very clearly genetically distinct from the others, indicating that these contemporaneous cases were not linked. Facility-wide screening of 47 staff and 107 patients did not identify any additional cases.ConclusionsThese data indicate that despite the outward appearance of a case cluster, the facility did not experience within-facility spread nor serve as the epicenter of a new outbreak, suggesting that the enacted rigorous infection control procedures (screening, masking, distancing) practiced stringently by patients and staff were sufficient to permit dialysis to proceed safely in a very high-risk population under pressure from increasing community spread. These data also demonstrate the utility of rapid turnaround SARS-CoV-2 sequencing in outbreak investigations in settings like ESRD facilities.

College reopening decisions during the SARS-CoV-2 pandemic represent a trade-off between competing risks to students, faculty and staff, and college finances. Additionally, risks taken in reopening colleges can impose significant burdens on individuals living in surrounding communities. Many colleges that reopened for in-person instruction have reported frequent SARS-CoV-2 outbreaks. La Crosse County, Wisconsin experienced a substantial SARS-CoV-2 outbreak (2,002 cases in September 2020) that coincided with the return to in-person instruction at three local academic institutions. Genomic sequencing of SARS-CoV-2 cases in La Crosse during that period found rapid expansion of two viral substrains. Although the majority of cases were among college-age individuals, from a total of 111 genomes sequenced we identified rapid transmission of the virus into more vulnerable populations. Eight sampled genomes represented two independent transmission events into two skilled nursing facilities, resulting in two fatalities. Our study highlights the very significant risks imposed by college administrator reopening decisions, not just on college-associated populations, but on vulnerable individuals in surrounding communities.

SARS-CoV-2 spread has proven to be especially difficult to mitigate in high risk settings, including nursing homes, cruises, prisons and various industrial settings. Among industrial settings, meat processing facilities in the United States have experienced particularly challenging outbreaks. We have sequenced SARS-CoV-2 whole viral genomes from individuals testing positive in an integrated regional healthcare system serving 21 counties in southwestern Wisconsin, northeastern Iowa and southeastern Minnesota, providing an overview of SARS-CoV-2 introduction and spread in a region spanning multiple jurisdictions with differing mitigation policies. While most viral introductions we detected were contained with only minor transmission chains, a striking exception was an outbreak associated with a meatpacking plant in Postville, IA. In this case, a single viral introduction led to unrestrained spread within the facility, affecting many staff and members of their households. Importantly, by surveilling viral sequences from the surrounding counties, we have documented the spread of this SARS-CoV-2 substrain from this epicenter to individuals in 13 cities in 7 counties in Iowa, Wisconsin and Minnesota, a region spanning 185 square miles. This study highlights the regional public health consequences of failures to rapidly act to mitigate viral spread in a single industrial setting.