High numbers indicate Covid-19 Omicron wave will likely peak soon, say experts

The height of the Omicron wave peak varies depending on a country's immunity levels and testing system. ST PHOTO: ONG WEE JIN

SINGAPORE - Health Minister Ong Ye Kung's comment to healthcare workers that a return to normalcy was within Singapore's grasp, coming on the back of record high infection numbers that topped 26,000 on Tuesday (Feb 22), took some people by surprise.

But in truth, it does reflect his grasp of Covid-19 transmissions.

Based on the experiences of other countries where the Omicron wave has already peaked, a sharp rise in cases usually foreshadows a fall in numbers, signalling the end of a Covid-19 wave.

"I suspect the peak will be soon (if it wasn't yesterday!)," said Associate Professor Alex Cook, an expert in healthcare modelling at the National University of Singapore's Saw Swee Hock School of Public Health. He expects the wave to peak within a fortnight.

In Singapore, historically, the largest number of infections usually appears on Tuesdays, following lower numbers at the weekends, on account of the reporting regime. There were 19,420 infections on the previous Tuesday (Feb 15), after which the numbers fell slightly, only to surge again on Feb 22.

Prof Cook said: "For most (countries), the time from the initial upswing to the peak has been about two months, though it's not always obvious when the initial upswing was since the Omicron wave often emerged from a Delta wave."

Based on reported genomes, Singapore's Omicron wave started in December last year, said Dr Sebastian Maurer-Stroh, executive director at the Agency for Science, Technology and Research's Bioinformatics Institute, who has been tracking Covid-19 genomes globally.

Although Omicron replaced the Delta variant in December, the big surge came only in January.

Prof Cook said the height of the Omicron wave peak varies depending on a country's immunity levels and testing system.

For comparison on a per million population basis, he said: "Denmark peaked with the equivalent of 160 per cent more cases than we currently have, and France 80 per cent more; Britain, the United States and Germany peaked with 10 per cent to 25 per cent fewer cases than we have, and Canada 70 per cent fewer."

Prof Cook added: "We can expect our own wave to peak when half or more of the population is infected, but because we don't diagnose all infections, it's not clear how far off we are from that."

Until this wave peaks, he said "hospitals will be really busy, so the main thing to do is avoid unnecessary visits to the emergency department".

Mr Ong made his comment in a letter he had written to encourage healthcare workers inundated with a heavy workload caused by the Omicron surge. He told them: "With each day, our society becomes stronger and we move closer to normalcy. So hang in there for a while more."

Associate Professor Hsu Li Yang, an infectious diseases expert at the NUS Saw Swee Hock School of Public Health, agrees that the Omicron wave should be peaking soon, certainly within weeks.

However, Prof Hsu, who also helps out in the wards, said the strain on the healthcare system today comes because the country is still in transition between fearing the pandemic and accepting it as endemic.

There are measures in place that are manpower- and resource-intensive but provide diminishing returns, he said, citing the Combined Test Centres where people who are well or mildly sick can go to get tested.

Given how widely the virus has spread, Prof Hsu said "there is probably a widening mismatch between actual benefit and effort" in testing, isolating and cohorting of even incidental Covid-19 cases in hospitals.

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Dr Asok Kurup, an infectious diseases doctor in the private sector, agrees that a lot of unnecessary tests are being done. He said: "Testing of all inpatients is uncovering a great deal of cases of recovered Covid-19 with no public health impact.

"But yet, until reviewed and endorsed as clear, important interventions like surgery may be deferred to the detriment of patient care."

He added that hospital beds are also being filled by people who are not really ill, but they still add to the workload of doctors and nurses.

Professor Dale Fisher, a senior infectious diseases consultant at the National University Hospital, also feels it is time to drop some of the existing measures.

"The pool of people more at risk of severe disease is shrinking as we have more people immune due to vaccine boosters, and naturally through infection," he said.

"I think it's hard to say now that these measures are limiting transmission or protecting that pool (of the vulnerable)."

Prof Fisher pointed out that most of the patients in intensive care units (ICU) are people who are not fully vaccinated or have not had their booster jabs.

Only 18 of the 46 people in ICU on Tuesday had received their booster shots - that is 39 per cent of the critically ill patients, in a population where 66 per cent have received booster shots.

Of the other 28 people, 14 were not fully vaccinated, and 14 had yet to receive their booster jabs.

This means that 30 per cent of patients in the ICU come from the 9 per cent of the population - including very young children for whom there is currently no vaccine - who have not been fully vaccinated.

Associate Professor Jeremy Lim from the NUS Saw Swee Hock School of Public Health added: "The Government really needs to evaluate whether all our Covid-19 measures are worth the effort for likely increasingly diminishing returns, and to start actively measuring the negative consequences of the restrictions on mental health, economic restoration, community engagement, et cetera."

Although the Omicron wave is likely to end soon, Prof Cook warns that there will be future waves, as happens with other endemic pathogens, as population immunity wanes and new variants emerge.

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