KUALA LUMPUR, March 12 — A lot of water has gone under the bridge ever since the novel coronavirus reached our shore from China travellers in late January 2020.
All nations have tightened the symptomatic screening at international point of entry even before the declaration of Public Health Emergency of International Concern (PHEIC).
Apart from that, countries have introduced various public health measures aimed at identifying the Covid-19 cases, ranging from limited screening to mass screening along with varying degrees of lockdown.
Limited screening, focusing mainly on inpatients with severe Covid-19 symptoms and health care staff at the beginning of pandemic was attributed to the lack of critical testing equipment in many countries.
Thus, most countries opted for public health intervention, such as lockdowns, to limit the spread of infection.
Sweden’s initial pandemic response was deemed as less aggressive, with selected testing on certain groups, with no general lockdown but focusing on mitigation phase in the early phase of pandemic (Ludvigsson, J. F. 2020).
Mass screening without consideration of epidemiological risk assessment has its inherent challenges, apart from being resource intensive.
Just to highlight a few: the appropriate time to conduct the screening, advice for individuals upon tested negative for Covid-19 regardless of symptoms, one-off or periodical screening and of course the choice of test (RTK-Ag or RT-PCR).
Slovakia is the first country that introduced mass screening of the targeted population. Despite having screened up to 90 per cent of the targeted population using antigen test kits, the positivity rate remained between 17-18% (tested by gold standard RT-PRC) before the mass screening.
Hence, investing on mass screening alone proved ineffective in reducing the viral transmission, though the initial intention was to avoid a total lockdown (Holt, E. 2021).
Instead of mass screening, our Ministry of Health (MOH), however, employs the strategy of targeted screening for Covid-19 (Chow, S.L. 2020), emphasising the essential steps of Seek (S), Test (T) and Isolate (I) of all Covid-19 positive cases as recommended by the World Health Organization (WHO).
Along with that, government also instituted a movement control order (MCO) for the public, which was made possible by the provision of these legislation: Prevention and Control of Infectious Diseases Act 1988 and the Police Act 1967.
All these strategies proved to be effective in flattening the epidemiological curve following the first MCO introduced on March 18, 2020.
The implementation of mandatory RTK-Ag testing on foreign workers by SOCSO started on 1 Dec in six states before expanding nationwide one month later.
Following which, many positive cases reported these days are attributed to this targeted screening, regardless of presence of symptoms or the potential Covid-19 exposure.
The remaining positive cases are the result of extensive close contact tracing from clusters in workplaces and of households, as well as those detected from symptomatic screening, with unknown history of exposure through continuous surveillance approach: influenza-like illnesses (ILI) and severe acute respiratory infection (SARI).
The Urgency Of Identifying Alternative Isolation Centres
The overall laboratory capacity for Covid-19 screening has increased since last year after the expanded testing was introduced to private health facilities that trained under MOH.
However, such increase is not matched with the number of facilities gazetted for isolation of positive cases.
The mandatory massive screening by SOCSO, if left unchecked, would certainly overwhelm the Covid-19 treating hospitals in a very short period of time.
To address that impending surge of positive cases requiring isolation, the idea of isolating positive cases of Category 1 and Category 2 away from hospital was conceived.
Hence, the government introduced the Low-Risk Covid-19 Centre (LRCC) (known as PKRC in Malay) to avoid the tertiary hospitals being occupied mainly by Covid-19 patients and keeping all or most hospital services in operation.
Covid-19 patients can be categorised into five categories based on the clinical presentation: Category 1 refers to asymptomatic/pre-symptomatic patients; Category 2 consists of patients with mild symptoms without pneumonia; Category 3 is for positive cases with pneumonia; Category 4 is for pneumonia cases that require supplemental oxygen; and Category 5 is for cases that require breathing assistance (Penang GH, 2020).
As early as February 2020, both WHO-China Joint Mission, Chinese Centre for Disease Control and Prevention reported on separate occasions that up to 80% of the laboratory confirmed Covid-19 patients have mild presentation, based on 55,924 and 72,314 patients respectively.
Most of the patients then experienced only fever and/or dry cough, while some had no symptoms at all at diagnosis. While the case definition of Covid-19 is dynamic, being revised numerous times by the Ministry of Health, the clinical presentation of those presented in Malaysia have been quite consistent with those findings reported by our counterparts in China in early 2020.
From the total of 5,889 patients treated in designated Covid-19 hospitals nationwide from Feb-April 2020 and Feb-May 2020, only 8-10 per cent of these patients had severe clinical outcomes as published by Wong et al. (2020) and Sim et al. (2020).
Elderly patients were mostly symptomatic, and for those with comorbidities, the risk of succumbing to poorer clinical outcomes was high.
Monitoring Home Isolation For Low-Risk Patients By Covid-19 Assessment Centres (CAC)
In the middle of January 2021, in addition to setting up LRCC, the government ordered Category 1 and Category 2 Covid-19 patients to isolate at home and remain contactable by the health authority.
These groups of low-risk Covid-19 patients were given a wristband and issued an order to isolate at home under Section 11(3) of the Prevention and Control of Infectious Disease Act 1988 [Act 342].
As per the WHO interim guideline on home care for patients with suspected or confirmed Covid-19 (WHO, 2020), the decision as to whether to isolate and care for an Covid-19 patient at home depends on the outcomes of the assessment on clinical evaluation of the patient, home environment and the accessibility for monitoring, evaluation of patient at home.
Among the factors to consider when assessing the home suitability for isolation include the number of housemates, number of washrooms/toilets, presence of caregiver, feasibility of isolating and maintaining proper hygiene at home.
The age of the patient, presence of any comorbidities, clinical presentation and likelihood of worsening symptoms are all important considerations in identifying those with low risk, Category 1 and Category 2 for home isolation.
There is no specific nor effective treatment to date for all Covid-19 patients. Hence, home isolation is crucial to break the chain of transmission with infection prevention and control measures along with supportive care when indicated (CDC, 2020).
However, there is still a risk for those patients, initially with low risk, to develop worsening symptoms during the period of home isolation that may warrant step up care in a hospital setting.
To minimise that risk, the Covid-19 Assessment Centre (CAC) has been established to carry out initial physical assessment and follow up by daily phone calls to monitor patients’ symptoms until Day 10 of isolation.
Thus, the CAC hotlines are meant for monitoring positive patients isolating at home while the Penang Covid-19 Information Careline (previously known as Penang Covid-19 Fever Call Centre) at 1-800-88-9133 serves as a platform to answer some general FAQs on Covid-19 from the public during office hours.
On January 25, 2021, a total of 152 CAC, led by primary health care teams had been established nationwide, with 27 (17.8 per cent) CAC operating in various health clinics within five districts in Penang.
Within two weeks into operation, the CAC had assessed a total of 60,052 Covid-19 patients, with 20,089 (33.5 per cent) patients meeting the criteria for home isolation.
These patients would otherwise have been admitted and subsequently overwhelmed hospital beds for infection and symptoms control.
However, low-risk Covid-19 cases without suitable sites for isolation would be placed under LRCC to prevent further transmission among household contacts.
In the event of the patient developing worsening symptoms, the Penang Covid-19 Unified Command Centre (PUCC), led by the emergency department, is tasked to coordinate the transfer of the patient to the designated hospital.
Duration Of Isolation Depends On Risk Of Viral Transmissibility, Not Incubation Period
Incubation period refers to the time taken for the development of first symptom after exposure to the causative agent. The incubation period for Covid-19 is thought to extend to 14 days, with a median time of four to five days. Up to 97 per cent of cases developed symptoms within 11.5 days of SARS-CoV-2 infection (CDC, 2020).
However, the duration of isolation depends on the viral load and risk of viral transmissibility. The viral load of SARS-CoV-2 and risk of transmissibility peak around the time of symptom onset, followed by a gradual decrease to a low level after about 10 days.
Thus, viral transmission after 10 days of illness has not been established despite the presence of viral genetic material which could still be detected by the RT-PCR test method.
Therefore, 10 days’ home isolation for average adults with mild to moderate Covid-19 is sufficient as the risk of infection is no longer than 10 days after symptom onset.
The Way Forward
The first phase of the national Covid-19 vaccination programme kicked off last week. Malaysia aims to vaccinate at least 80 per cent of the 32 million population within a year as the nation is looking forward to revive its economy that was affected by the Covid-19 pandemic since last year.
Herd immunity is achieved by vaccination alone, not by exposing the population to the infectious virus.
At present, industry players may be keen to embark on a continuous Covid-19 surveillance programme for early detection and isolation of cases from workplace.
However, without a proper, systematic risk assessment, such random sampling of workers for Covid-19 testing may not achieve its goal and is unlikely to be cost effective at all.
Pooled testing method is well known for its potential resource-efficient strategy in detecting early community transmission of Covid-19.
Given that new and active clusters are still being reported today, the window period to optimise such a sampling method may be long gone.
Dr Chow Sze Loon is a public health medicine specialist who previously served in the CPRC (Crisis Preparedness and Response Centre) in Penang, which acts as the Public Health Emergency Operation Centre in the Penang State Health Department that carries out surveillance, preparedness and response activities on infectious diseases outbreaks, crises, disasters and emergencies in the state.
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Holt, E. (2021). Covid-19 testing in Slovakia. The Lancet. Infectious Diseases, 21(1), 32.
Chow, S.L. (2020). Covid-19 targeted screening in Malaysia. PMPS Ann Mag, 88: 46-49
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