SG-APSIC1204: Time-based deisolation of generally asymptomatic immunocompetent COVID-19 patients on day 8 of infection to clean wards is safe

Objectives: The National University Hospital (NUH) is a tertiary-care teaching hospital in Singapore with 60% of patients in 6–8-bed cubicles. NUH recently changed to a time-based deisolation criterion for immunocompetent COVID-19 patients in cohort wards who are afebrile and improved but did not meet the antigen rapid test negative criteria at day 5–6 and who required continued hospital care. The MOH guidelines and studies of viral load trajectory from the SARS-CoV-2 δ (delta) variant suggest that by day 8 of infection, viral loads drop and the risk of transmission is low. We defined a cycle threshold (Ct) value ≥25 as the point at which virus cultures are negative. We assessed whether a time-based deisolation at day 8 correlated with Ct ≥25 during the SARS-CoV-2 ο (omicron) variant pandemic surge. Methods: Data for patients and staff with confirmed positive COVID-19 PCR between January to March 2022 were collected. These data comprised a convenience sample collected retrospectively by the epidemiology team and the obstetrics and gynecology team and were used to deisolate patients. Nasopharyngeal (NP) swabs were sent for PCR for all admissions, to confirm diagnosis, for deisolation and/or transfer, and for staff suspected to have COVID-19 as part of hospital staff policy. Results: Overall, 403 observations were obtained. For 145 NP swabs tested by SARS-CoV-2 PCR on day 1, the median Ct value was 19.55 (IQR, 9.01). The median Ct for 87 observations on day 2 was 15.95 (IQR, 3.45). The median Ct value for 14 observations on day 8 was 24.22 (IQR, 5.19). From day 9 to day 37, with 47 observations, the Ct was generally >25. Conclusions: During the SARS-CoV-2 ο (omicron) surge, NP swabs sent on day 8 had a median Ct value of 24.22. After day 8, the median Ct was >25. The discontinuation of isolation precautions on day 8 balances the use of dedicated COVID-19 beds with risk mitigation of transmission for recovered patients who require ongoing hospitalization. Small sample size and heterogeneous reasons for testing NP swabs after day 5 likely skewed our results and limits the generalizability of our results.

Duration of exposure is the most important risk factor for nosocomial COVID-19 in open multibed wards

Background: The National University Hospital (NUH) is a 1,200 bed tertiary-care hospital with no documented nosocomial transmission of COVID-19 among patients for the first year and a half of the pandemic, despite 65% of the patients being housed in 4- to 8-bedded open cubicles with shared bathrooms. However, this arrangement changed in late September 2021 with large community clusters including in healthcare institutions nationally associated with the spread of the δ (delta) variant of SARS-CoV-2. We conducted a retrospective review of hospital epidemiology data to determine risk factors for SARS-COV-2 transmission during this period. Methods: Index patients were defined as the first patient in an open cubicle with a confirmed positive SARS-CoV-2 PCR test. Contacts were defined as being in the same cubicle as a patient before isolation from 2 days before symptom onset, up to 7 days from positive test if asymptomatic. Clinical and patient movement data were obtained manually from routine clinical records. Proximity of the contact from the index was classified as within, or more than, 2 m away, according to the prevailing definition from the Singapore Ministry of Health. A univariate analysis was performed to identify risk factors for nosocomial acquisition of SARS-CoV-2. The analysis was deemed exempt from ethics review (reference no. NHG-DSRB-2021/01026). Results: From October 1 to November 30, 2021, 30 index cases occurred in open cubicles identified (median, 9 days after admission;IQR, 19 days). Contact tracing yielded 211 contacts, of whom 10 (4.7%) were infected. Linear regression analysis found the duration of contact for each hour spent in the same room as the index case was the only statistically significant risk variable for contracting COVID-19, with an odds ratio 1.02 (Table 1). Conclusions: Patients in open cubicles are at risk for nosocomial transmission of COVID-19 and other infections. The duration of contact appeared to be more important than vaccination status of index or ward ventilation status. Larger multicentered studies are needed to validate this finding, which has significant implications for infection prevention strategies and pandemic planning.Funding: NoneDisclosures: None

Role of Occupational Health Services in Planning and Implementing of Staff COVID-19 Vaccination Clinic: A Tertiary Hospital Experience in Singapore.

CONTEXT: Healthcare workers all over the world were prioritized for vaccination against COVID-19 in view of the high-risk nature of their job scopes when vaccines were first available in late 2020. Vaccine hesitancy was an important problem to tackle in order to achieve a high vaccination rate, especially for vaccines that were developed using mRNA technology. We aimed to use the '3Cs' model to address vaccine hesitancy to ensure maximal uptake of the Pfizer-BioNTech vaccine among healthcare workers in a tertiary hospital in Singapore. METHODS: Various measures were used to reduce the confidence, complacency, and convenience barriers. The staff vaccination clinic was on-site and centralized, with appointments given in advance to ensure vaccine availability and to reduce wait time, providing convenience to staff. Direct and repeated communications with the staff via multiple channels were used to address vaccine safety and efficacy so as to promote confidence in the vaccines and overcome complacency barriers. To further encourage staff to get vaccinated, staff were allowed time off for vaccination when at work. Staff with a high risk of exposure to COVID-19 or those caring for immunocompromised patients were prioritized to take the vaccines first. The collection of data on adverse events was via on-site monitoring and consultation at Occupational Health Clinic (OHC). RESULTS: Nearly 80% of staff had completed vaccination when the vaccination exercise ended at the end of March 2021. With the loosening of the contraindications to vaccination over time, staff vaccination rates reached 89.3% in early July and nearly 99.9% by the end of the year. No major or serious vaccine-related medication or administration errors were reported. No staff had anaphylaxis. CONCLUSIONS: By using the '3Cs' model to plan out the vaccination exercise, it is possible to achieve a high vaccination rate coupled with effective and customized communications. This multi-disciplinary team approach can be adapted to guide vaccination efforts in various settings in future pandemics.

Safety and side effect profile of Pfizer-BioNTech COVID-19 vaccination among healthcare workers: A tertiary hospital experience in Singapore.

INTRODUCTION: Vaccination remains a key strategy to living endemically with COVID-19. The Pfizer-BioNTech COVID-19 vaccine was first granted interim authorisation for use in Singapore in December 2020. With overseas studies published about the safety and side effect profiles of mRNA COVID-19 vaccines focusing mainly on non-Asian populations, we described the side effects of Pfizer-BioNTech COVID-19 vaccination experienced by the healthcare workers (HCWs) in a tertiary hospital in Singapore. METHODS: Data were obtained from the Occupational Health Clinic (OHC) at the National University Hospital in Singapore, which monitored staff for any adverse effects within 30 minutes post vaccination on-site and any adverse effects after that. A cross-sectional study among the vaccinated HCWs was conducted using an online survey, which established basic demographics, histories of allergies or atopic disorders, and adverse events encountered after dose 1 and dose 2 of vaccination. RESULTS: No anaphylaxis was reported. Most common symptom was giddiness (32.7%) experienced by HCWs within 30 minutes. Adverse events attended post-vaccination by OHC were generally mild and self-limiting. From the survey, odds of experiencing an adverse event after dose 2 was significantly higher than after the first dose, especially for fever/chills (odds ratio [OR] 22.5). Fever/chills, injection site reactions, headache, aches and pains, and feeling unwell were significantly more common in HCWs below 60 years compared to those ≥60 years. An allergy to food (adjusted OR 2.7) and a history of eczema/sensitive skin (adjusted OR 2.6) were associated with a skin reaction not at injection site. CONCLUSION: The side effects experienced after Pfizer-BioNTech COVID-19 vaccines are generally self-limiting and mild, with no anaphylaxis reported.