key: cord-326852-gm98s8a3
authors: Teo, Wan-Yee
title: Implications for Border Containment Strategies when COVID-19 Presents Atypically
date: 2020-07-24
journal: Public Health
DOI: 10.1016/j.puhe.2020.07.019
sha: 
doc_id: 326852
cord_uid: gm98s8a3

Abstract Objectives For a large part of COVID-19 pandemic, Singapore had managed to keep local cases in the single digits daily, with decisive measures. Yet we saw this critical time point when the imported cases surged through our borders. The gaps which we can and have efficiently closed, using a public health approach and global border containment strategies, are aptly illustrated through this case. This critical point of imported case surge, has resulted in large spike of daily local cases sustained through community transmission, up to 120/day within a very short time frame. We were able to rapidly bring this under control. Study Design This is a case study of a patient who passed through our borders, with COVID-19 masquerading as a resolved sore throat. Methods The events were prospectively documented. Results We present a case of a 21 year-old student returning from Nottingham. He presented with sore throat as the only symptom the few days prior his return, and on arrival at our border (Day 7 from initial symptoms), his sore throat had already resolved. The events leading up to his COVID-19 diagnosis highlight the gaps of the international screening processes at the global border entry, and the potential consequences of community chain transmission through imported COVID-19 cases. Conclusions An important global border control measure to implement quickly, will be to expand the symptom list to isolated sore throat, and/or a prior history of recent symptoms (resolved). This may capture a larger proportion of imported cases at border entry point, for more effective containment. This piece will be equally relevant to the general physicians, emergency care physicians, otolaryngologists and anaesthetists, who are at higher risk of encountering a throat visualization during intubation and routine examination. This information can be useful to countries with low resources or insufficient COVID-19 testing kits.

In the early months of the COVID-19 pandemic, Singapore had managed to keep the number of local cases down to single figures daily through decisive measures. We identified a critical time point when the number of imported cases surged through our borders that resulted in a large spike of daily local cases, up to 120/day within a very short time frame, that was further sustained through community transmission. Using a public health approach and global border containment strategies, we were able to rapidly bring this under control. This short communication highlights how an atypical presentation of COVID-19 (sore throat) could breach border containment. We present some effective strategies for COVID-19 screening at border entry.

A 21 year old student returning from Nottingham presented with sore throat as the only symptom a few days prior his return. On arrival at our border (Day 7 from initial symptoms), his sore throat had already resolved. Self-taken photographs by the patient during the initial symptomatic phase (Day 5) with the sensation of sore throat, and on Day 7 and 12, when the sensation of sore throat had resolved, revealed persistent pharyngitis. The patient had no fever during his symptomatic phase and had performed temperature checks twice-a-day with a thermometer. He had experienced some nasal congestion initially which was attributed to his underlying allergic rhinitis.

At border entry, this patient had declared his symptom of sore throat, which had resolved. The patient directly moved from the airport to his Stay Home Notice (SHN) hotel to stay in isolation.

Following the instructions on the information sheet from Singapore Global Network (a division in the Singapore Economic Development Board which broadens and deepens the overseas network of Singapore citizens) available online, 2 the patient and his family contacted the People's Association (a government-supported statutory board to promote racial harmony and social cohesion in Singapore) to clarify the symptom of a resolved sore throat, and highlighted patient's contact history with an Italy-returning medical student during a fencing sparring. Italy, at that point, had the most COVID-19 cases globally. Staff at People's Association rapidly facilitated the patient to be picked up in a dedicated ambulance to National Center of Infection Disease, Singapore, where a chest x-ray done was normal, and the swab test was positive for COVID-19 (Day 8 of initial symptoms).

This patient's parents transported him from the airport to his SHN hotel. All 3 individuals (patient and patient's parents) were wearing surgical masks in the enclosed air-conditioned car space (windows were not wound down). The duration of transport was around 1 hour or less. The patient had changed to a new surgical mask, wiped down his suitcase and personal belongings with disinfecting wipes, and washed his hands before meeting his parents and getting into the car. About 36 hours later, the father started experiencing dry throat, dry cough and runny nose. Patient's mother experienced dry throat. Patient's brother (whom did not have any direct contact with the patient, was picked up in the same car but separately from the patient about 1.5 hours after) developed fever of 37.7ᵒC, bodyache, nasal congestion and throat discomfort ~48 hours later from the car ride. It is unclear if a chain transmission occurred through parents at home, to the patient's brother who did not come into contact with the patient, or through the consecutive use of a common transport vehicle. Swab test results were however negative for the rest of the family*. In retrospect, patient recalled unusual/impaired sense of smell for the first 4 days during initial symptoms.

The events leading up to his COVID-19 diagnosis highlight the gaps of the international screening processes at the global border entry, and the potential consequences of community chain transmission through imported COVID-19 cases. Here, we emphasize some effective strategies for COVID-19 screening at the global border entry.

Fever and/or other respiratory symptoms are frequently highlighted at the global border entry as indications for swab tests. However, sore throat alone may be an unclear symptom for individuals to declare. This is a case of COVID-19 with isolated sore throat, which has recovered. We will suggest a detailed breakdown of the symptoms/education posters placed at global border entry points to facilitate declarations and diagnosis.

This patient had declared his symptom of sore throat, which had resolved. Overseas returning persons to Singapore have been placed on a mandatory 14-day Stay Home Notice (SHN) since 20

March 2359h. The availability of the instructions on the information sheet online from Singapore Global Network, 2 and the provision of a hotline assistance from the People's Association (government-supported), were the key factors and contact point which allowed the patient to be identified and rapidly facilitated to be picked up while isolated in his SHN hotel, in a dedicated ambulance to National Center of Infection Disease, Singapore. We highlight the importance and efficiency of a national online COVID-19 network resource for overseas returning persons, facilitation through government agency and a closed loop transportation in the containment of COVID-19 spread.

This patient's parents who transported him from the airport to his SHN hotel, and patient's brother (whom did not have direct contact with the patient, but was picked up in a common transport vehicle afterwards) developed symptoms despite negative swab test results*. A study on environmental contamination by symptomatic COVID-19 patients in airborne infection isolation rooms, demonstrated that air samples were negative despite the extent of environmental contamination. 3 However, swabs taken from the air exhaust outlets tested positive, suggesting that small virus-laden droplets may be displaced by airflows and deposited on vents. 3 

In retrospect, patient recalled unusual/impaired sense of smell for the first 4 days during initial symptoms. Some new reports suggest loss of smell or taste as COVID-19 symptoms. [4] [5] [6] Loss of smell and loss of taste occurred between 68-85.6%, and 71-88% respectively in two European cohorts reported very recently. [5] [6] But this knowledge was not available at the earlier phase of the COVID-19 pandemic when the patient was symptomatic, and these symptoms may not be readily offered by a non-suspecting patient. Physicians need to actively probe for this history. Our frontline physicians worldwide also need a high index of suspicion encountering at least 3 geographic variants of COVID-19 that have been reported so far. While loss of smell and taste were reported in two large European cohorts, 5-6 a report 7 published mid-April 2020 on 393 patients in New York City indicated gastrointestinal symptoms of diarrhea (23.7%), nausea and vomiting (19.1%) appeared to be more common than in China (where these symptoms occurred in 4 to 5% of patients). Coupled with the knowledge that COVID-19 can spread asymptomatically, these unusual symptoms may be the initial manifestation of the illness.

We hope that global collaborative efforts at border screening can contain and slow down the rapid spread of COVID-19 internationally. Availability of a government-supported go-to online resource can unite efforts between returning persons and national directions in containing this pandemic.

Another strategy to ease the border point screening and declaration logistics, can be to set up an online pre-arrival declaration by government agency, where returning persons/students can selfreport any symptoms or resolution of symptoms, contact history, which can be reviewed prior arrival. Returning individuals can then be pre-issued an electronic QR code/tagged queue number through email, which allows the suspect cases to be channelled to a separate queue or screening area with physical distancing precautions. This will allow suspect cases to be effectively prioritized during declaration screening. As of 17 March 2020, our Ministry of Foreign Affairs in Singapore has issued a statement to encourage Singaporean students studying overseas to consider returning home soon. 8 We will expect an increase in the number of imported cases from this group. A high index of suspicion for COVID-19 when identifying an isolated sore throat on clinical examination, will be equally relevant to the general physicians, emergency care physicians, otolaryngologists and anaesthetists, 9 who are at higher risk of encountering a throat visualization during intubation and routine examination (Fig. 1) . This information can be useful to countries with low resources or insufficient COVID-19 testing kits.

Our Ministry of Health released the figures -90% of Singapore's imported cases over 3 days (18-21

March) did not show any symptoms at border entry. 10 An important global border control measure to implement quickly, will be to expand the symptom list to isolated sore throat, and/or a prior history of recent symptoms (resolved). This may capture a larger proportion of imported cases at border entry point, for more effective containment. Majority 70.8% (34/48) imported cases (cohort from 23 March, Fig. 2) were returning from the United Kingdom. 8 This is an important message to deliver to the larger global community in our efforts to control the rapidly escalating pandemic. 

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The author thanks the patient and his family for providing the information, case history and images.
