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 (R
o) 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.
Table 1.
Probable occupationally acquired COVID-19 among 25 locally transmitted cases in Singapore,
4–11 February 2020
Case description (case no.a)
No. of cases
Staff working in a retail store selling complementary health products primarily serving
Chinese tourists (Cases 19, 20, 34, 40)
4
Domestic worker who worked for Case 19 (Case 21)
1
Tour guide who led tour group from China (Case 24)
1
Jewellery store worker who served Chinese tourists (Case 25)
1
Multinational company staff attending an international business meeting in Singapore
(Cases 30, 36, 39)
3
Taxi driver (Case 35)
1
Private hire car driver (Case 37)
1
Resorts World Sentosa employee (Case 43)
1
Security officer who served quarantine order to two persons (Case 44)
1
Casino worker (Case 46)
1
Cluster of two workers at the same construction siteb (Cases 42 and 47)
2
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 20–22 January 2020 in Singapore. At this event, healthy company workers interacted
with other infected participants, which resulted in the transmission of the virus
to three employees based in Singapore. Besides those infected from Singapore, one
employee from Malaysia, two participants from South Korea and one staff member from
the UK were also infected. They presented as cases after leaving Singapore.
Crew on board cruise ships with infected passengers are also at risk. At least 10
cases have been reported among the 1035 crew on the liner Diamond Princess, which
is currently docked in Yokohama with around 3600 people quarantined since 3 February
2020. A Hong Kong man boarded the ship on 20 January in Yokohama at the beginning
of a 14-day round trip cruise. The passenger sailed from Yokohama to Hong Kong, where
he disembarked on 25 January. The ship continued its journey, until news was received
that the passenger tested positive on 1 February 2020. The Diamond Princess returned
to Yokohama a day early, and has been quarantined since then, with guests isolated
in their cabins and screened [10]. The quarantine period will end on 19 February 2020.
Another cruise ship, the Dutch liner Westerdam, sailed out of Hong Kong on 1 February
2020. It was turned away by the Philippines, Taiwan, Korea, Japan, Thailand and the
US territory of Guam, because of fears arising from the COVID-19 outbreak—even though
there was apparently no confirmed case on board [11]. The ship was finally allowed
to dock in Sihanoukville, Cambodia after 13 days at sea.
Besides fears of contagion from people on board cruise ships, which have been likened
to ‘floating petri dishes’, fears are also widespread on land. There are increasing
reports of HCWs being shunned and harassed by a fearful public because of their occupation.
A Member of Parliament in Singapore highlighted what he termed as ‘disgraceful actions’
against HCWs stemming from fear and panic [12]. Some examples of behaviour described
were:
Taxi drivers reluctant to pick up staff in medical uniform.
A healthcare professional’s private-hire vehicle cancelled because she was going to
a hospital.
A nurse in a lift asked why she was not taking the stairs and that she was spreading
the virus to others by taking the lift.
A nurse scolded for making the Mass Rapid Transit train “dirty” and spreading the
virus.
An ambulance driver turned away by food stall workers.
However, not all the reactions from the public towards HCWs have been negative. There
are probably an equal number of stories of public support and encouragement. Members
of the public have showed their appreciation for HCWs and have volunteered to help
the more vulnerable in society [13]. For example, a ride-hailing transport operator
started a new service offering a dedicated 24-h service for HCWs travelling from work.
Volunteers have also stepped forward to distribute hand sanitizers and masks to the
elderly and vulnerable in their community, while sharing important public health messages.
Such reactions are reminiscent of behaviour during the 2003 SARS outbreak, where not
only the general public, but even close family members were afraid of being infected
by HCWs exposed to the disease. A survey of over 10 000 HCWs in Singapore during the
SARS outbreak of 2003 reported that many respondents experienced social stigmatization.
Almost half (49%) thought that ‘people avoid me because of my job’ and 31% felt that
‘people avoid my family members because of my job’. For example, some parents of schoolchildren
forbade their children to play or be close to children of HCWs. A large number (69%)
of HCWs also felt that ‘people close to me are worried they might get infected through
me’ [14]. On the other hand, there was also massive public support for HCWs, who were
hailed as heroes in the fight against the disease. Most of the HCWs (77%) felt appreciated
by society.
COVID-19 is the first new occupational disease to be described in this decade. Our
experiences in coping with the previous SARS-CoV and MERS-CoV outbreaks have better
prepared us to face this new challenge. While the explosive increase in cases in China
has overwhelmed the health care system initially, we know that public health measures
such as early detection, quarantine and isolation of cases can be effective in containing
the outbreak. All health personnel should be alert to the risk of COVID-19 in a wide
variety of occupations, and not only HCWs. These occupational groups can be protected
by good infection control practices. These at-risk groups should also be given adequate
social and mental health support [15], which are needed but which are sometimes overlooked.