Interactive: Rising Community Transmission Threatens Larger Covid-19 Outbreak

PETALING JAYA: Health experts have cautioned about the risk of Covid-19 community transmissions, especially in the Klang Valley, as sporadic cases now show a rising trend.

Universiti Malaya professor of epidemiology and public health Prof Dr Sanjay Rampal defined community transmissions as newly diagnosed cases which cannot be linked to a previous cluster.

“Based on the reporting methods of new cases, these are cases that were identified either by symptomatic screening, surveillance systems, or pre-operative screening.

Community transmission, he said, could represent the tip of the iceberg in terms of undiagnosed cases.

Covid-19 cases involving healthcare workers in the Klang Valley illustrates the possibility of community transmission, where the source of many of the infections could not be identified and had spread before being noticed.

On Thursday, Selangor health director Datuk Dr Sha’ari Ngadiman said that some 50 Hospital Tengku Ampuan Rahimah (HTAR) staff were infected, noting that rising severe acute respiratory infection cases that sought treatment at HTAR might have been the cause.

The next day, Health director-general Tan Sri Dr Noor Hisham Abdullah revealed that 1,359 healthcare workers had been infected since the third wave started on Sept 20, as he associated the rise in the number of cases among healthcare workers in the Klang Valley with the rise of Covid-19 cases in the community.

Of the total infected healthcare workers, 587 (33.1%) was attributed to community transmission, while 409 (23.1%) cases are still under investigation and 58 (3.3%) infections are from unknown causes.

An analysis by The Star on reports of Covid-19 cases in the Klang Valley between Oct 16 and Dec 20 found that 18.9% out of the total 21,489 cases were not linked to any cluster or close contact.

Most of the positive cases which were unlinked were detected via work-related screening at 68.9% or 2,796 positive cases, followed by symptomatic screening at 19.5% (792 cases), private screening at 2.7% (110 cases), healthcare related screening which involved both healthcare workers and patients at 1.6% (65 cases), SARI screening (66 cases) at 1.6% and travel related screening at 1.5%.

Other screenings such as community screenings, screening of detainees, prisoners and foreigners as well as post-mortem screenings contributed to 4.3% of the total sporadic cases throughout the 66-day period.

Sanjay, who acknowledged the rising trend of sporadic cases in the community in recent weeks, explained that the Health Ministry has not classified the cases affecting Hospital Tengku Ampuan Rahimah (HTAR) staff and all other cases as “unlinked cases”.

He clarified that the cases may be later identified as first-generation community transmission or multigenerational.

“The issue of linkage occurs during the individual outbreak management after contact tracing and subsequent analysis.

“A crude and easy method is to define those cases not linked at incident reporting as unlinked, ” he said and highlighted that there may be further finalised reports following the outbreak investigation.

Universiti Malaya Department of Social and Preventive Medicine public health medicine specialist Assoc Prof Dr Rafdzah Ahmad Zaki said it will be difficult to contain community transmission as those infected may only be experiencing mild symptoms or are asymptomatic

“Community transmissions pose a bigger threat because we do not know who is infected or is spreading the disease.

“This also means that there are more cases out there that are not detected, ” she said, advising that Covid-19 tests need to done to as many people as possible, especially among high-risk groups.

Universiti Malaya epidemiologist Prof Datuk Dr Awang Bulgiba Awang Mahmud said the level of unlinked cases in Selangor indicated that infections are entrenched in the community.

He cited the example of cases involving foreign workers in Malaysia as a possible source of community transmission.

A large portion of Malaysia’s Covid-19 cases in the past month has been contributed by foreign workers. The Teratai cluster, involving glove manufacturer Top Glove workers, is currently the biggest and most active infection cluster in the country, recording a total of 5,746 positive cases since Nov 7.

“Worker screenings which have been done include those who do not display symptoms, so when there is a significant number of asymptomatic unlinked cases, it is a cause for great concern, ” Prof Awang Bulgiba said, noting a similar trend seen in Sabah in September.

As an example, Singapore’s Straits Times on Tuesday (Dec 15) reported that nearly half of the republic’s 323,000 migrant workers living in dormitories have had a Covid-19 infection.

The report said that while 54,505 workers have tested positive for the virus via a polymerase chain reaction or PCR test, an additional 98,289 have had a positive result from a serology test, which checks for a previous infection.

This meant that 152,794 workers in the dorms in the neighbouring country have tested positive in PCR or serology tests or both.

Prof Awang Bulgiba suggested that efforts be increased to improve living conditions for foreign workers in Malaysia as it can help reduce the risk of community transmissions in the long term.

In the meantime, he said that repeated screenings at workplace with large concentrations of migrant workers should be considered.

Awang proposed that antibody tests be done randomly in Selangor to identify the sero-prevalence rate in the community.

“A sero-prevalence survey looks for antibodies to a disease, which is evidence of past infection.

“A high proportion of people with antibodies to Covid-19 will indicate that the disease is entrenched in the community, ” he noted, adding that a decision can then be made whether to change the strategy from containment to mitigation.

Dr Awang suggested the setting up of an extensive real-time syndromic surveillance system in the community, by making use of the government and private clinics with Internet access.

“This could give us some early warning and perhaps we could catch some those infections before it got to this stage, ” he said.

Malaysian Medical Association president Prof Datuk Dr Subramaniam Muniandy said the level of public compliance to Covid-19 standard operating procedures was crucial since the lifting of most inter-district and inter-state travel restrictions since Dec 7.

Universiti Putra Malaysia medical epidemiologist Assoc Prof Dr Malina Osman advised everyone to stay home, avoid crowds and unnecessary traveling as active Covid-19 cases have hit a worrying level, with two thirds of the cases found in Selangor and Kuala Lumpur.

“If awareness is translated into proper compliance, the potential serious consequences will always be under control, ” she said.


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