While Health Minister Ong Ye Kung has earlier noted that the number of unlinked cases is “not as relevant as before” now that Singapore is no longer “chasing down every single case”, Temasek CEO Ho Ching appears to have a different opinion on this.
“We are not there yet, and unlinked cases are still relevant for the purpose of getting a sense whether we are having a runaway gallop or a steady trot,” said the wife of Prime Minister Lee Hsien Loong in a Facebook post on Thursday (9 Sep).
Her remarks came after the Ministry of Health (MOH) announced on Wednesday a revamp of its daily COVID-19 reports, in which it will no longer provide information on the number of linked and unlinked cases on the grounds that “this is no longer as relevant as before”.
Mr Ong had also noted that it was “timely” for MOH to revamp its daily COVID-19 reports so as to reflect “salient issues” being faced in this new phase of the COVID-19 battle.
“In the past, we tried to suppress every cluster, trace down to the last infection, and try to eliminate them,” said the Minister.
“With the more transmissible Delta variant, this will be very challenging to do and we may not be prepared to pay the price of doing so, in the form of border closures, circuit breaker and heightened alert. It is just not sustainable,” he added.
Mdm Ho, however, highlighted that a “daily case breakdown” between linked and unlinked cases, as well as between “quarantined linked and unquarantined linked” should still be reported.
“This gives us a sense of the pipeline of potential new cases ahead, and whether our contact tracing is keeping up. We need to keep these signals alive until about end of the year,” she remarked.
In response to her post, former Nominated Member of Parliament (NMP) Calvin Cheng commented that the number of unlinked cases “tells us nothing” if the country no longer pursuing a “COVID-zero policy”.
He suggested that the “only practical use” for linking cases is to “inform close contacts to self-isolate”.
“In the past, we counted linked cases in order to stub out every case. Therefore the number of unlinked cases tells us how successful we were in doing this.
“If we are pursuing an endemic policy, the number of unlinked cases is merely a subset of the total number of cases. It doesn’t provide any further illumination anymore,” said Mr Cheng.
Mdm Ho replied to his comment saying that the unlinked cases are “nodes of community transmission”, and that living with the virus does not mean that the Government should “leave it to burn out of control”.
“Suppose we have 100,000 seniors who are unvaccinated. And about 25% will get very sick or die (this goes up exponentially with age and not linearly – but let’s just use 25% to cover from 60 to over 100 years old).
“If all 90,000 get infected within 90 days, that is 1,000 a day on average, of whom 250 will get very sick. But the very sick are not just sick for one day – so the stock counts as much as the flow towards whether we will run out of beds.
“And this doesn’t take into account that we wouldn’t have a steady daily drip, but will start small and multiply exponentially. So we could be seeing not 250 new very sick cases, but more like 750-1500 at the peak.
“But if these 90,000 get infected more slowly – say over 300 days. This means an average of 300 a day of new infections, with 75 very sick cases. This could clip at a peak of say 100-150 new daily cases. This is more manageable,” she explained.
Mdm Ho further noted that living with the virus does not mean that the Government should stop caring about the pace of new cases, but rather they should try to “squeeze things down to zero”.
“But everything we can do to reduce the speed of spread is critical, from wearing masks to contact tracing to quick isolation to prevent further spread.
“In other words, we can live with the virus, if we can keep the R to around 1, and not let it blow out of control at its natural R0 of 5~8, with more people now thinking it is closer to 8 than to 5,” she added.
The R number indicates the virus’s actual transmission rate at a given time. If the R number is higher than one, it means the number of cases increase.
According to Mdm Ho, the numbers of unlinked cases and unquarantined linked cases are both “important lead indicators” of further spread of COVID-19.
“The speed of rise tells us we are losing control with R of more than 1, and the higher above 1, the more out of control. The absolute also tells a story. We have superspreader phenomenon.
“For the old variants, some 10-20% are responsible for 80-90% of secondary transmissions. But there are also ultrasupereaders with ultra high viral loads. These could be just 2%, but they could provide 90% of the viral loads among those tested positive.
“So if we have 5 community loads daily, chances of superspreader cluster bursting out suddenly is low. But if we have 500 community unlinked cases, there is a high chance we will be dealing with superspreader clusters which can spiral out of control,” she said.
Mdm Ho concluded by saying that contact tracing, wearing of masks, and other safety management measures are still necessary to reduce infections to manageable levels.
