key: cord-0074033-vyrz5rdf
authors: Wee, Liang En; Conceicao, Edwin Philip; Sim, Jean Xiang-Ying; Venkatachalam, Indumathi; Wijaya, Limin
title: Correspondence on “The Low Yield of SARS-CoV-2 Rapid Antigen Testing in Screening Asymptomatic Hospital Visitors in Low-incidence Settings”
date: 2022-01-27
journal: Int J Infect Dis
DOI: 10.1016/j.ijid.2022.01.049
sha: eafa538115607690d3b3779b122d489653718915
doc_id: 74033
cord_uid: vyrz5rdf

nan

We note the interest by Boddeti et. al. (Boddeti et al., 2022) in our article that reported the use of rapid-antigen detection (RAD) in screening asymptomatic hospital visitors for SARS-CoV-2 at the point-of-entry during the COVID-19 pandemic (Wee et al., 2022) .

During the study period 0.3% (31/9679) of admitted inpatients tested positive for COVID-19. In contrast, retrospective contact tracing together with RAD testing for visitors staying ≥30 minutes identified COVID-19 cases amongst <0.01% (6/72605) of hospital visitors. In June 2021, Singapore was at Level 1 of the US CDC's Travel Health Notice Thresholds (CDC, 2020), with an incidence of <50 cases of COVID-19 over the past 28 days per 100,000 population. Only in end-September 2021 was Singapore raised to Level 3 (100-500 cases over the past 28 days per 100,000 population). As of June 2021, 58.1% of the local population had received a single vaccine dose, with 36.8% of the population having had two doses (MOH, 2021). Only visitors who intended to visit for ≥30 minutes received RAD testing. A single test result was taken as valid for the purposes of entry triage for 24 hours; while frequent visitors would have had serial daily testing, it was infeasible to require two separate negative tests 24-48 hours apart for a single hospital visit. As previously cited, usage of the national digital contact-tracing tool to register entry/exit to hospital premises was made compulsory for all visitors, who had to pass through mandatory perimeter screening regardless of visit duration (Wee et al., 2021) ; allowing retrospective contact-tracing of potential exposures arising from all visitors who subsequently tested positive for COVID-19 elsewhere. While the large majority (82.4%, 10521/12763) of visitors remaining on hospital premises for ≥30 minutes did undergo RAD testing, a small minority were not tested, because they overstayed beyond the initial visit duration that was declared. Only visitors with recent previous PCR-confirmed COVID-19 infection received exemption from RAD testing. No CONSORT flow diagram was included as this was an observational study.

During the study period, a total of six visitors with PCR-confirmed COVID-19 infection were thus identified and the epidemiological details are given in Table 1 . Identifying information for visitors were omitted as the majority of them were not patients at our hospital and this was not relevant for contact-tracing investigations. For the single case of PCR-confirmed COVID-19 infection picked up on RAD screening (Case 6), RAD tests on preceding visits were negative.

The Low Yield of SARS-CoV-2

Rapid Antigen Testing in Screening Asymptomatic Hospital Visitors in Low-incidence Settings

COVID-19 and Your Health

Update on local COVID-19 situation 30 th

Containment of COVID-19 and reduction in healthcare-associated respiratory viral infections through a multi-tiered infection control strategy

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

The authors report no conflicts of interest.

This research was not grant-funded

As this study was conducted as part of outbreak investigation, ethics approval was not required under our institutional review board guidelines.