Nosocomial SARS-CoV-2 transmission in multi-bedded hospital cubicles over successive pandemic waves: Lower mortality but wider spread with Omicron despite enhanced infection-prevention measures.

BACKGROUND: Increased transmissibility of severe-acute-respiratory-syndrome-coronavirus-2(SARS-CoV-2) variants, such as the Omicron-variant, presents an infection-control challenge. We contrasted nosocomial transmission amongst hospitalized inpatients across successive pandemic waves attributed to the Delta- and Omicron variants, over a 9-month period in which enhanced-infection-prevention-measures were constantly maintained. METHODS: Enhanced-infection-prevention-measures in-place at a large tertiary hospital included universal N95-usage, routine-rostered-testing (RRT) for all inpatient/healthcare-workers (HCWs), rapid-antigen-testing (RAT) for visitors, and outbreak-investigation coupled with enhanced-surveillance (daily-testing) of exposed patients. The study-period lasted from 21st June 2021-21st March 2022. Chi-square test and multivariate-logistic-regression was utilized to identify factors associated with onward transmission and 28d-mortality amongst inpatient cases of hospital-onset COVID-19. RESULTS: During the Delta-wave, hospital-onset cases formed 2.7% (47/1727) of all COVID-19 cases requiring hospitalisation; in contrast, hospital onset-cases formed a greater proportion (17.7%, 265/1483; odds-ratio, OR = 7.78, 95%CI = 5.65-10.70) during the Omicron-wave, despite universal N95-usage and other enhanced infection-prevention measures that remained unchanged. The odds of 28d-mortality were higher during the Delta-wave compared to the Omicron-wave (27.7%, 13/47, vs. 10.6%, 28/265, adjusted-odds-ratio, aOR = 2.78, 95%CI = 1.02-7.69). Onward-transmission occurred in 21.2% (66/312) of hospital-onset cases; being on enhanced-surveillance (daily-testing) was independently associated with lower odds of onward-transmission (aOR = 0.18, 95%CI = 0.09-0.38). Costs amounted to $USD7141 per-hospital-onset COVID-19 case. CONCLUSION: A surge of hospital-onset COVID-19 cases was encountered during the Omicron-wave, despite continuation of enhanced infection-prevention measures; mortality amongst hospital-onset cases was reduced. The Omicron variant poses an infection-control challenge in contrast to Delta; surveillance is important especially in settings where infrastructural limitations make room-sharing unavoidable, despite the high risk of transmission.

Environmental contamination and evaluation of healthcare-associated SARS-CoV-2 transmission risk in temporary isolation wards during the COVID-19 pandemic.

BACKGROUND: Temporary isolation wards have been introduced to meet demands for airborne-infection-isolation-rooms (AIIRs) during the COVID-19 pandemic. Environmental sampling and outbreak investigation was conducted in temporary isolation wards converted from general wards and/or prefabricated containers, in order to evaluate the ability of such temporary isolation wards to safely manage COVID-19 cases over a period of sustained use. METHODS: Environmental sampling for SARS-CoV-2 RNA was conducted in temporary isolation ward rooms constructed from pre-fabricated containers (N = 20) or converted from normal-pressure general wards (N = 47). Whole genome sequencing (WGS) was utilized to ascertain health care-associated transmission when clusters were reported amongst HCWs working in isolation areas from July 2020 to December 2021. RESULTS: A total of 355 environmental swabs were collected; 22.4% (15/67) of patients had at least one positive environmental sample. Patients housed in temporary isolation ward rooms constructed from pre-fabricated containers (adjusted-odds-ratio, aOR = 10.46, 95% CI = 3.89-58.91, P = .008) had greater odds of detectable environmental contamination, with positive environmental samples obtained from the toilet area (60.0%, 12/20) and patient equipment, including electronic devices used for patient communication (8/20, 40.0%). A single HCW cluster was reported amongst staff working in the temporary isolation ward constructed from pre-fabricated containers; however, health care-associated transmission was deemed unlikely based on WGS and/or epidemiological investigations. CONCLUSION: Environmental contamination with SARS-CoV-2 RNA was observed in temporary isolation wards, particularly from the toilet area and smartphones used for patient communication. However, despite intensive surveillance, no healthcare-associated transmission was detected in temporary isolation wards over 18 months of prolonged usage, demonstrating their capacity for sustained use during succeeding pandemic waves.

Favorable outcomes of COVID-19 in vaccinated hematopoietic stem cell transplant recipients: A single-center experience.

INTRODUCTION: A high incidence of mortality and severe COVID-19 infection was reported in hematopoietic stem cell transplant (HSCT) recipients during the early phases of the COVID-19 pandemic; however, outcomes with subsequent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, such as the omicron variant, have yet to be reported. Additionally, rollout of COVID-19 vaccinations in subsequent pandemic waves may modify COVID-19 disease severity and mortality in this immunocompromised population. We describe COVID-19 outcomes among a highly vaccinated population of HSCT recipients at a single center during successive waves of community transmission arising from the SARS-CoV-2 delta and omicron variants. METHODS: We retrospectively reviewed medical records of all HSCT recipients at our institution who tested positive for SARS-CoV-2 from May 2021 to May 2022. Descriptive statistics were reported; the chi-square test was utilized to identify factors associated with 90-day all-cause mortality and severity of COVID-19 infection. RESULTS: Over the 1-year study period, 77 HSCT recipients at our center contracted COVID-19 (43 allogenic; 34 autologous). Twenty-six (33.8%) patients were infected with the SARS-CoV-2 delta variant, while 51 (66.2%) had the SARS-CoV-2 omicron variant. Thirty-nine (50.6%) patients required hospitalization. More than 80% had received prior COVID-19 vaccination (57.1% with two doses, 27.3% with three doses). The majority (90.9%) had mild disease; only one (1.3%) patient required mechanical ventilation. Active hematological disease at time of COVID-19 infection was associated with increased odds of mortality [odds ratio (OR) = 6.90, 95% confidence interval (CI) = 1.20-40]. The 90-day all-cause mortality was 7.8% (six patients). Infection with the omicron variant (vs. delta) was associated with less severe illness (OR = 0.05, 95% CI = 0.01-0.47) and decreased odds of mortality (OR = 0.08, 95% CI = 0.01-0.76). Being on immunosuppression (OR = 5.10, 95% CI = 1.10-23.60) and being unvaccinated at disease onset (OR = 14.76, 95% CI = 2.89-75.4) were associated with greater severity of COVID-19 infection. CONCLUSION: We observed favorable outcomes with COVID-19 infection in a cohort of vaccinated HSCT patients. The SARS-CoV-2 omicron variant was associated with both less severe illness and decreased odds of mortality. As COVID-19 moves toward endemicity, early access to treatment and encouraging vaccination uptake is crucial in mitigating the challenge of COVID-19 management among HSCT recipients. Surveillance and assessment of clinical outcomes with new SARS-CoV-2 variants also remains important in this immunocompromised population.

Respiratory surveillance wards as a strategy to reduce nosocomial transmission of COVID-19 through early detection: The experience of a tertiary-care hospital in Singapore.

OBJECTIVES: Patients with COVID-19 may present with respiratory syndromes indistinguishable from those caused by common viruses. Early isolation and containment is challenging. Although screening all patients with respiratory symptoms for COVID-19 has been recommended, the practicality of such an effort has yet to be assessed. METHODS: Over a 6-week period during a SARS-CoV-2 outbreak, our institution introduced a "respiratory surveillance ward" (RSW) to segregate all patients with respiratory symptoms in designated areas, where appropriate personal protective equipment (PPE) could be utilized until SARS-CoV-2 testing was done. Patients could be transferred when SARS-CoV-2 tests were negative on 2 consecutive occasions, 24 hours apart. RESULTS: Over the study period, 1,178 patients were admitted to the RSWs. The mean length-of-stay (LOS) was 1.89 days (SD, 1.23). Among confirmed cases of pneumonia admitted to the RSW, 5 of 310 patients (1.61%) tested positive for SARS-CoV-2. This finding was comparable to the pickup rate from our isolation ward. In total, 126 HCWs were potentially exposed to these cases; however, only 3 (2.38%) required quarantine because most used appropriate PPE. In addition, 13 inpatients overlapped with the index cases during their stay in the RSW; of these 13 exposed inpatients, 1 patient subsequently developed COVID-19 after exposure. No patient-HCW transmission was detected despite intensive surveillance. CONCLUSIONS: Our institution successfully utilized the strategy of an RSW over a 6-week period to contain a cluster of COVID-19 cases and to prevent patient-HCW transmission. However, this method was resource-intensive in terms of testing and bed capacity.

Detection of viable SARS-CoV-2 in deep respiratory specimens despite negative nasopharyngeal SARS-CoV-2 RT-PCR: Occult COVID-19 as an unsuspected cause of pulmonary infiltrates in immunocompromised patients.

Background: Prolonged shedding/relapse of COVID-19 infection has been reported, particularly in patients who received anti-CD20 agents (eg. rituximab). However, cases of occult COVID-19, in which SARS-CoV-2 persistence in lung parenchyma is diagnosed despite clearance from nasopharyngeal (NP) specimens, are uncommon. Case summary: We describe two cases of occult COVID-19 in immunocompromised patients. Both patients had received rituximab previously. Both cases initially presented as ground-glass infiltrates on lung imaging; the diagnosis was originally not suspected due to repeated demonstration of negative SARS-CoV-2 from NP specimens, and alternative etiologies were originally considered. Persistence of SARS-CoV-2 in lung parenchyma, however, was demonstrated on bronchoalveolar lavage (BAL) specimens; additionally, isolation of viable SARS-CoV-2 virus and detection of SARS-CoV-2 nucleocapsid and spike-protein antigen in lung tissue on immunohistochemistry close to 3-months from primary infection strongly suggested ongoing viral persistence and replication as a driver of the lung parenchymal changes, which resolved after antiviral treatment. Discussion: Occult COVID-19 can be a cause of unexplained ground-glass infiltrates on lung imaging; negative NP samples do not rule out SARS-CoV-2 persistence and invasive sampling must be considered. The unsuspected presence of viable virus on BAL, however, highlights that procedurists perfoming aerosol-generating-procedures during an ongoing pandemic wave must also practise appropriate infection-prevention precautions to limit potential exposure.

Dengue and COVID-19: Managing Undifferentiated Febrile Illness during a "Twindemic".

BACKGROUND: During the COVID-19 pandemic, distinguishing dengue from COVID-19 in endemic areas can be difficult, as both may present as undifferentiated febrile illness. COVID-19 cases may also present with false-positive dengue serology. Hospitalisation protocols for managing undifferentiated febrile illness are essential in mitigating the risk from both COVID-19 and dengue. METHODS: At a tertiary hospital contending with COVID-19 during a dengue epidemic, a triage strategy of routine COVID-19 testing for febrile patients with viral prodromes was used. All febrile patients with viral prodromes and no epidemiologic risk for COVID-19 were first admitted to a designated ward for COVID-19 testing, from January 2020 to December 2021. RESULTS: A total of 6103 cases of COVID-19 and 1251 cases of dengue were managed at our institution, comprising a total of 3.9% (6103/155,452) and 0.8% (1251/155,452) of admissions, respectively. A surge in dengue hospitalisations in mid-2020 corresponded closely with the imposition of a community-wide lockdown. A total of 23 cases of PCR-proven COVID-19 infection with positive dengue serology were identified, of whom only two were true co-infections; both had been appropriately isolated upon admission. Average length-of-stay for dengue cases initially admitted to isolation during the pandemic was 8.35 days (S.D. = 6.53), compared with 6.91 days (S.D. = 8.61) for cases admitted outside isolation (1.44 days, 95%CI = 0.58-2.30, p = 0.001). Pre-pandemic, only 1.6% (9/580) of dengue cases were admitted initially to isolation-areas; in contrast, during the pandemic period, 66.6% (833/1251) of dengue cases were initially admitted to isolation-areas while awaiting the results of SARS-CoV-2 testing. CONCLUSIONS: During successive COVID-19 pandemic waves in a dengue-endemic country, coinfection with dengue and COVID-19 was uncommon. Routine COVID-19 testing for febrile patients with viral prodromes mitigated the potential infection-prevention risk from COVID-19 cases, albeit with an increased length-of-stay for dengue hospitalizations admitted initially to isolation.

Linking sporadic hospital clusters during a community surge of the severe acute respiratory coronavirus virus 2 (SARS-CoV-2) B.1.617.2 delta variant: The utility of whole-genome sequencing.

Sporadic clusters of healthcare-associated coronavirus disease 2019 (COVID-19) occurred despite intense rostered routine surveillance and a highly vaccinated healthcare worker (HCW) population, during a community surge of the severe acute respiratory coronavirus virus 2 (SARS-CoV-2) B.1.617.2 δ (delta) variant. Genomic analysis facilitated timely cluster detection and uncovered additional linkages via HCWs moving between clinical areas and among HCWs sharing a common lunch area, enabling early intervention.

Sporadic outbreaks of healthcare-associated COVID-19 infection in a highly-vaccinated inpatient population during a community outbreak of the B.1.617.2 variant: The role of enhanced infection-prevention measures.

Sporadic clusters of health care-associated COVID-19 infection occurred in a highly vaccinated health care-workers and patient population, over a 3-month period during ongoing community transmission of the B.1.617.2 variant. Enhanced infection-prevention measures and robust surveillance systems, including routine-rostered-testing of all inpatients and staff and usage of N95-respirators in all clinical areas, were insufficient in achieving zero health care-associated transmission. The unvaccinated and immunocompromised remain at-risk and should be prioritized for enhanced surveillance.

Utilisation of SARS-CoV-2 rapid antigen assays in screening asymptomatic hospital visitors: mitigating the risk in low-incidence settings.

Retrospective contact tracing, enabled by the use of automated visitor-management systems and digital contact tracing, together with rapid antigen detection (RAD) for SARS-CoV-2 among visitors staying ≥ 30 minutes, identified COVID-19 cases in < 0.01% (6/72 605) of hospital visitors to a large hospital campus over an 8-week study period. The potential for nosocomial transmission of SARS-CoV-2 from hospital visitors was thus very low, and could be further mitigated by universal mask-wearing among staff and visitors.