Occupational risks for COVID-19 infection

Abstract

Coronaviruses are enveloped RNA viruses found in mammals, birds and humans. At present, six coronavirus species are known agents for illnesses in humans. Four viruses—229E, OC43, NL63 and HKU1—are prevalent and can cause respiratory symptoms. The other two—severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV)—are zoonotic in origin and can cause fatalities [1]. SARS-CoV originated in Guangdong Province, China and was responsible for the severe acute respiratory syndrome outbreaks in 2002 and 2003. It rapidly spread across the globe and resulted in 8098 reported cases and 774 deaths (case-fatality rate, 9.6%) in 37 countries. MERS-CoV originated in the Middle East and caused severe respiratory disease outbreaks in 2012. Since 2012, there have been 2494 reported MERS-CoV cases resulting in 858 deaths (case-fatality rate, 34%) in 27 countries. There were also several rapid outbreaks reported, mainly in hospitals in Saudi Arabia, Jordan and South Korea [2]. On 31 December 2019, the World Health Organization (WHO) China office was informed of cases of pneumonia of unknown aetiology detected in Wuhan city in Hubei Province, central China [3]. By 9 January 2020, WHO released a statement on the cluster of cases, which stated that ‘Chinese authorities have made a preliminary determination of a novel (or new) coronavirus, identified in a hospitalized person with pneumonia in Wuhan’ [4]. The virus was initially referred to as 2019-nCoV, but has since been re-named as SARS-CoV-2 by the WHO on 12 February 2020. Early indications are that the overall case-fatality rate is around 2%. An analysis of the first 425 cases provided an estimated mean incubation period of 5.2 days (95% confidence interval [CI] 4.1–7.0) and a basic reproductive number (Ro) of 2.2 (95% CI 1.4–3.9) [1]. It is possible that people with Coronavirus Disease 2019 (COVID-19) may be infectious even before showing significant symptoms [5]. However, based on currently available data, those who have symptoms are causing the majority of virus spread. The WHO declared this disease as a Public Health Emergency of International Concern (PHEIC) on 30 January 2020 [6]. A significant proportion of cases are related to occupational exposure. As this virus is believed to have originated from wildlife and then crossed the species barrier to infect humans, it is not unexpected that the first documented occupational groups at risk were persons working in seafood and wet animal wholesale markets in Wuhan. At the start of the outbreak, workers and visitors to the market comprised 55% of the 47 cases with onset before 1 January 2020, when the wholesale market was closed. In comparison, only 8.5% of the 378 cases with onset of symptoms after 1 January 2020 had a link with exposure at the market [1]. As cases increased and required health care, health care workers (HCWs) were next recognized as another high-risk group to acquire this infection. In a case series of 138 patients treated in a Wuhan hospital, 40 patients (29% of cases) were HCWs. Among the affected HCWs, 31 (77.5%) worked on general wards, 7 (17.5%) in the emergency department, and 2 (5%) in the intensive care unit (ICU). There was apparently a super-spreader patient encountered in the hospital, who presented with abdominal symptoms and was admitted to the surgical department. This patient infected >10 HCWs in the department [7]. China’s Vice-Minister at the National Health Commission said that 1716 health workers had been infected in the country as of Tuesday 11 February 2020, among whom 6 have died [8]. Outside of China, the first confirmed case of COVID-19 infection in Singapore was announced on 23 January 2020 by the Ministry of Health, Singapore (MOH-Sg). The MOH-Sg issues daily press reports to describe case details of confirmed COVID-19 patients. As of 11 February 2020, a total of 47 cases have been confirmed [9]. Among the first 25 locally transmitted cases, 17 cases (68%) were probably related to occupational exposure (Table 1). They included staff in the tourism, retail and hospitality industry, transport and security workers, and construction workers. Probable occupationally acquired COVID-19 among 25 locally transmitted cases in Singapore, 4–11 February 2020 aThe case no. denotes the order of cases according to the time of announcement by the Ministry of Health, Singapore. The first 18 cases were imported cases. bTwo other cases (Cases 52 and 56) were reported from the same worksite 2 days later. Probable occupationally acquired COVID-19 among 25 locally transmitted cases in Singapore, 4–11 February 2020 aThe case no. denotes the order of cases according to the time of announcement by the Ministry of Health, Singapore. The first 18 cases were imported cases. bTwo other cases (Cases 52 and 56) were reported from the same worksite 2 days later. An international business meeting for 109 staff was organized by a multinational company from 20