Introduction:
The novel coronavirus disease (COVID-19) or SARS-CoV-21 gained attention after a citywide lockdown was implemented in Hubei, China.2 To date, COVID-19 had infected more than 3,000,000 people in the world. This pandemic has currently left more than 230,000 dead and almost two-thirds of the world’s countries locked down.3,4
Malaysia recorded its first confirmed COVID case on 25th January 2020.5 At the time of writing, Malaysia tallied 6176 confirmed cases and 103 deaths.6 Kuching, the most populated city in Sarawak, was among the areas with most confirmed COVID-19 cases and death in Malaysia.7 Majority of the cases in Malaysia were contributed by a few clusters, including one religious assembly event in East Malaysia.8
SARS-CoV-2 virus displayed high transmissibility (R0 of 2.68)9 and longer incubation period (6 days)9 compared to the Middle East Mediterranean virus. The virus can transmit form human-to-human via respiratory droplets, aerosol, and fecal-oral route. These natures of the virus may explain the rapid spread of the global pandemic and high case-fatality rate.10
Healthcare workers are not spared from this disease.11China12 recorded 3.47% and Netherlands 4-9.5% of infected healthcare workers (HCW).13 Contact tracing revealed most of the infected HCW acquired the infection from the community.14 The total number of HCW with COVID-19 infection will continue to rise, given that many countries have yet to reach the peak of the outbreak.
Patients with COVID-19 infection displayed a wide spectrum of disease severity,14 including asymptomatic or mild symptoms.13,15 Statistical modeling correctly predicted near to 18% of asymptomatic infection in the Diamond Princess cruise ship cluster.16 Most HCW (80%) with confirmed COVID infection expressed mild symptoms without a strong epidemiological link.13,17 HCW expressing mild or no symptom could be the vulnerable group to be prioritized for the COVID-19 serology screening.18
Because symptoms of COVID-19 infection differed across the board, it is difficult to separate the infected and the healthy by clinical and epidemiological factors alone. WHO recommended the virus nucleic acid Real-Time Polymerase Chain Reaction test (RT-PCR) test as a laboratory diagnostic tool.19 However, the use of RT-PCR testing is currently rationalized due to testing capacity with priority given to specific individuals, i.e. higher risk.18 Thus, human antibody rapid test may be an alternative because of this limitation.20
Human antibody acute response (IgM) to COVID-19 infection begins at the median timing of 5 days from illness onset.21 IgG antibody, which represents possible past exposure is usually detectable in plasma or seroconvert from IgM after day 10 of illness.22,23 PCR tests are more sensitive to yield positive results in the first week of illness. This sensitivity reduces towards the end of the second week.24 Hence this antibody temporal relationship can be used to guide the COVID-19 diagnosis after one week of illness25 and identify a person with previous undiagnosed infection.18 It has proven good sensitivity and specificity to supplement the test of molecular laboratory diagnosis.26
Being the only non-COVID-19 tertiary hospital and the only public cardiology centre in Sarawak, the Sarawak Heart Centre (SHC) plays a supporting role as the healthcare burden escalated in the other regional medical facility designated as a COVID-19 hospital healthcare, the Sarawak General Hospital (SGH). To date, no cases of confirmed COVID had been admitted or treated in our centre. All cases fulfilling the criteria for person under investigation (PUI) were referred to the designated COVID-19 centre. There is a total of 757 staff, including 71 working in non-clinical field. None of the healthcare workers in our centre have been diagnosed with COVID-19 infection thus far.
Our hospital’s COVID-19 taskforce team decided to assess the possibility of unknown disease transmission due to either community or nosocomial exposure among our healthcare workers. Knowing the antibody response of our staff can also give us some idea of the effectiveness of our in-hospital infection control measures. Because RT-PCR test is prioritized for high-risk patients only, we chose the COVID-19 antibody serology test as the mode of investigation. This survey is self-funded with approval from hospital administration to protect staff’s wellbeing during this pandemic. Our decision echoes World Health Organization’s (WHO) suggestion to prioritize COVID-19 testing among healthcare worker to prevent potential nosocomial spread.18