Risk of transmission of COVID-19 from healthcare workers returning to work after a 5-day isolation, and kinetics of shedding of viable SARS-CoV-2 variant B.1.1.529 (Omicron).

OBJECTIVES: There have been limited data on the risk of onward transmission from individuals with Omicron variant infections who return to work after a 5-day isolation. We evaluated the risk of transmission from healthcare workers (HCWs) with Omicron variant who returned to work after a 5-day isolation and the viable virus shedding kinetics. METHODS: This investigation was performed in a tertiary care hospital, Seoul, South Korea. In a secondary transmission study, we retrospectively reviewed the data of HCWs confirmed as COVID-19 from March 14 to April 3, 2022 in units with 5 or more COVID-19-infected HCWs per week. In the viral shedding kinetics study, HCWs with Omicron variant infection who agreed with daily saliva sampling were enrolled between February and March, 2022. RESULTS: Of the 248 HCWs who were diagnosed with COVID-19 within 5 days of the return of an infected HCW, 18 (7%) had contact with the returned HCW within 1 to 5 days after their return. Of these, 9 (4%) had an epidemiologic link other than with the returning HCW, and 9 (4%) had contact with the returning HCW, without any other epidemiologic link. In the study of the kinetics of virus shedding (n=32), the median time from symptom onset to negative conversion of viable virus was 4 days (95% CI, 3 to 5 days). CONCLUSIONS: Our data suggest that the residual risk of virus transmission after 5 days of isolation following diagnosis or symptom onset is low.

Erratum: Correction of Funding in the Article "Rates of COVID-19 Infection Among Healthcare Workers in Designated COVID-19 Wards and General Wards".

This corrects the article on p. e308 in vol. 37, PMID: 36345254.

Effect of COVID-19 vaccination on transmission among healthcare workers in South Korea

Background: SARS-CoV-2 infection of healthcare workers (HCWs) occasionally occurs via acquisition from their colleagues. Data regarding the infection rates of HCWs with close contact and non–close contacts of HCWs are limited. In addition, the protective effect of COVID-19 vaccination against transmission between HCWs is unknown. We evaluated the infection rates of HCWs with close contact and non–close contact of infected HCWs and the effect of COVID-19 vaccination on transmission among HCWs in a tertiary-care hospital in South Korea. Methods: This study was performed in a tertiary-care hospital in Korea. We analyzed the COVID-19 cases and contacts among HCWs from January to December 2021. We reviewed the vaccination status of confirmed and exposed HCWs, the type of vaccination, and the infection rate according to the contact. We performed subgroup analyses in individuals who had been diagnosed since July 2021 when the δ (delta) variant became the dominant strain in South Korea. Transmission was defined based on their spatiotemporal epidemiologic association. Results: During the study period, 173 HCWs had COVID-19, and 2,693 HCWs were exposed to them. Among them, 18 (1.52%) of 1,186 close contacts and 13 (0.86%) of 1,507 non–close contacts had a positive SARS-CoV-2 test (P = .11). When the index cases had been fully vaccinated, the infection rate of close contacts was 0.85% (7 of 820), whereas the infection rate of close contacts was 3.01% (11 of 366) when the index had not been fully vaccinated (P = .005). However, the infection rate of non–close contacts was not different according to the vaccination status of index (0.83% vs 0.89%;P = .90). During the period of δ (delta) variant being dominant, the infection rate of close contacts was significantly lower when the index case had been fully vaccinated index than in cases with a non–fully vaccinated index case (0.85% vs 5.88%;P < .001). Conclusions: Transmission to colleagues was significantly lower from vaccinated HCWs than from nonvaccinated HCWs, and this finding was more significant in the era of the δ (delta) variant. Our findings support the importance of vaccination in HCWs.Funding: NoneDisclosures: None

Usefulness of universal SARS-CoV-2 PCR testing for inpatients and their caregivers during the omicron era.

Background: Since January 2022, the Omicron variant has become the dominant strain in South Korea, and COVID-19 cases among hospitalized patients and their guardians or caregivers have increased. We evaluated the usefulness of universal periodic screening for SARS-CoV-2 in patients and resident caregivers in a South Korean tertiary care hospital. Methods: We evaluated the reason for testing in COVID-19 confirmed patients and resident caregivers during their hospitalization from March 3 to 31, 2022. The rate of positive PCR universal testing in hospital (or residency) (HD) on days 3 and 7 in asymptomatic patients and caregivers were evaluated. The test for SARS-CoV-2 was done by RT-PCR. Results: During the study period, 677 patients were diagnosed with COVID-19. The reasons for testing were the symptoms (226 (33%)), pre-admission test (183 (27%)), exposure to COVID-19 (124 (18%)), universal testing on HD 3 (94 (14%)), and that on HD 7 (34 (5%)). Caregivers (n = 340) were tested during their residency due to exposure to COVID-19 cases, 103 (30%); universal testing on HD 3, 90 (26%); symptom development, 46 (14%); pre-stay, 39 (11%); and universal testing on HD 7, 29 (9%). The positive test rates of inpatients and caregivers on HD 3 and HD 7 were as follows: 1.4% (93/6553) and 2.1% (55/2646) in inpatients, and 1.3% (79/5989) and 1.7% (35/2106) in caregivers, respectively. Conclusions: Universal testing, regardless of symptom or epidemiologic link, is useful for detecting pre-symptomatic and asymptomatic COVID-19 cases among hospitalized patients and caregivers and preventing a nosocomial outbreak during the Omicron era.

Rates of COVID-19 Infection Among Healthcare Workers in Designated COVID-19 Wards and General Wards.

BACKGROUND: To evaluate the effects of isolating coronavirus disease 2019 (COVID-19) patients in general wards, we compared the rates of COVID-19 infection in nurses and nursing assistants working in COVID-19 designated wards and in general wards of our hospital from 1 October 2021 to 21 April 2022. METHODS: This study was conducted in a 2,700-bed tertiary care hospital in Seoul, Korea. Designated wards comprised single, negative pressure rooms and a 100% outdoor air system. RESULTS: During the study period, a total of 2,698 nurses and nursing assistants were employed at our hospital, of whom 310 (11%) were working in the designated wards, and the remaining 2,388 (89%) in the general wards, and among whom 1,158 (43%) were diagnosed with COVID-19. The healthcare workers (HCWs) in the designated wards were less frequently diagnosed with COVID-19 than those in the general wards (31% vs. 45%, P < 0.001). During the period before patients with COVID-19 were isolated in general wards, and during the period after these cases were isolated in general ward, HCWs in designated wards were less frequently infected with the virus than those in general wards (7% vs. 11%, P = 0.039; and 23% vs. 33%, P < 0.001, respectively). CONCLUSION: HCWs in designated wards have a lower rate of contracting COVID-19 than those in general wards. A lack of exposure to undiagnosed cases and their caregivers, greater care with social distancing outside the hospital, higher rates of 3-dose vaccinations, and the use of isolation rooms with negative pressure may be associated with this finding.

Evaluation of In-Hospital Cluster of COVID-19 Associated With a Patient With Prolonged Viral Shedding Using Whole-Genome Sequencing.

BACKGROUND: Patients with hematologic malignancies may produce replication-competent virus beyond 20 days of SARS-CoV-2 infection. However, data regarding the transmission of SARS-CoV-2 from patients with prolonged viral shedding is limited. METHODS: In May 2022, four additional cases of COVID-19 were reported in a hematologic ward at a tertiary care hospital in South Korea, after an 8-week isolation of a patient with prolonged viral shedding. We performed whole-genome sequencing (WGS) of SARS-CoV-2 to evaluate the possibility of post-isolation transmission from this prolonged viral shedding. RESULTS: A patient (case 1) with acute myeloid leukemia was released from isolation 54 days after the diagnosis of COVID-19 based on rising Ct value of up to 29.3, and moved to a six-patient room. On days 10 and 11 post-isolation, his doctor (case 2) and 2 patients who were his roommates (case 3, 4) had positive SARS-CoV-2 PCR results. Additionally, 16 days post-isolation, another patient (case 5) in a remote room had positive SARS-CoV-2 PCR result. All the three patients were hospitalized for ≥ 14 days when they were diagnosed with SARS-CoV-2 infection. Except for case 3, the remaining 4 cases were available for WGS, which revealed that case 1 exhibited a 7 nucleotides difference in comparison to cases 4 and 5 and case 2 displayed a 20 nucleotides difference compared with case 1, while sequences of cases 4 and 5 were identical. CONCLUSIONS: Despite the possibility of transmission from the patient with prolonged viral shedding, no evidence of the transmission of SARS-CoV-2 from the patient with prolonged positive RT-PCR using WGS was found.

Google Glass-Supported Cooperative Training for Health Professionals: A Case Study Based on Using Remote Desktop Virtual Support.

PURPOSE: Observation of medical trainees' care performance by experts can be extremely helpful for ensuring safety and providing quality care. The advanced technology of smart glasses enables health professionals to video stream their operations to remote supporters for collaboration and cooperation. This study monitored the clinical situation by using smart glasses for remote cooperative training via video streaming and clinical decision-making through simulation based on a scenario of emergency nursing care for patients with arrhythmia. PARTICIPANTS AND METHODS: The clinical operations of bedside trainees, who is Google Glass Enterprise Edition 2(Glass EE2) wearers, were live streamed via their Google Glasses, which were viewed at a remote site by remote supporters via a desktop computer. Data were obtained from 31 nursing students using eight essay questions regarding their experience as desktop-side remote supporters. RESULTS: Most of the participants reported feeling uneasy about identifying clinical situations (84%), patients' condition (72%), and trainees' performance (69%). The current system demonstrated sufficient performance with a satisfactory level of image quality and auditory communication, while network and connectivity are areas that require further improvement. The reported barriers to identifying situations on the remote desktop were predominantly a narrow field of view and motion blur in videos captured by Glass EE2s, and using the customized mirror mode. CONCLUSION: The current commercial Glass EE2 can facilitate enriched communication between remotely located supporters and trainees by sharing live videos and audio during clinical operations. Further improvement of hardware and software user interfaces will ensure better applicability of smart glasses and video streaming functions to clinical practice settings.

Adverse Reactions Following the First Dose of ChAdOx1 nCoV-19 Vaccine and BNT162b2 Vaccine for Healthcare Workers in South Korea.

BACKGROUND: We performed a prospective survey on the adverse reactions following the first dose of two types of vaccines against coronavirus disease 2019 (COVID-19) in healthcare workers (HCWs) in South Korea. METHODS: HCWs at a tertiary referral hospital in Seoul, South Korea, received a chimpanzee adenovirus-vectored vaccine (ChAdOx1 nCoV-19) or an mRNA-based vaccine (BNT162b2) between March 5 and March 26, 2021. The HCWs were asked to report adverse reactions through a mobile self-report questionnaire for three days after vaccination. RESULTS: A total of 7,625 HCWs received the first dose of ChAdOx1 or BNT162b2 vaccine during the study period. Of them, 5,866 (76.9%) HCWs (ChAdOx1, n = 5,589 [95.3%]; BNT162b2, n = 277 [4.7%]) participated at least once in the survey, of whom 77% were female and 86% were younger than 50 years. The overall adverse reaction rate was 93% in the ChAdOx1 group and 80% in the BNT162b2 group (P < 0.001). Both local and systemic reactions were more commonly reported in the ChAdOx1 group, and the difference was larger in systemic reactions such as fever and fatigue. In the ChAdOx1 group, the incidence of adverse reactions was significantly higher in females and those in the younger age groups, while the BNT162b2 group showed such difference according to age. CONCLUSION: In our prospective survey, vaccine-associated adverse reactions were more commonly reported in the ChAdOx1 group than in the BNT162b2 group. Females and younger age groups experienced vaccine-associated adverse reactions more frequently.

Universal Screening of Severe Acute Respiratory Syndrome Coronavirus 2 with Polymerase Chain Reaction Testing after Rally of Trainee Doctors.

There were two rallies of medical students and trainee doctors, where 9,000 participants gathered. We performed polymerase chain reaction (PCR)-based universal screening for the participants using pooling at a tertiary care hospital. Around 609 (94%) of 646 participants underwent PCR tests for severe acute respiratory syndrome coronavirus 2; all of them tested negative. Our data suggested low transmission rates in open air mass gatherings when appropriate personal protective practices were followed.