SINGAPORE - Singapore's high vaccination and booster rates give the country a window of opportunity to ease some Covid-19 measures, especially as the Omicron variant causes a less severe form of the disease, suggest several experts.

Easing measures does not mean doing away with all safety measures, they said. But there are some that may no longer be as useful.

The experts, however, were divided, with some thinking that it was not yet time to let society's guard down, given the rapid spike in case numbers that could follow. That risks overwhelming the health system, even if many might have less severe illness.

The range of views emerged in the light of the World Health Organisation's (WHO) recent warning to countries not to relax Covid-19 measures prematurely.

On Tuesday (Feb 1), Dr Maria Van Kerkhove, the WHO's technical lead on Covid-19, said that the world body was concerned about countries with low levels of vaccination putting vulnerable people at risk of severe illness or death should they open up prematurely.

WHO officials added that it was premature for countries to declare victory over Covid-19, or rush to treat the disease as being in an endemic or end state.

But Associate Professor Hsu Li Yang, an infectious diseases expert at the National University of Singapore Saw Swee Hock School of Public Health, argued that this latest advisory did not apply to Singapore.

He said: "WHO's advice does not apply to us at all, since I think we are all agreed that we will not remove every last measure and return to a pre-Covid-19 state."

Professor Teo Yik Ying, dean of the school, added that "with high vaccination uptake, as well as a resilient and well-prepared healthcare system, Singapore is well placed to relax its measures to continue on the trajectory to live with Covid-19".

Local experts generally felt that measures that are no longer needed include restrictions on the number of people participating in outdoor activities, and even the wearing of masks outdoors.

With the rapid spread of the Omicron variant, contact tracing no longer adds much value, especially since people can spread the disease while asymptomatic, they added.

Prof Teo suggested allowing more travellers to come in through vaccinated travel lanes (VTLs) and increasing group sizes from the current five.

On community restrictions, he said: "I do not see the need to continue to forbid the use of parks and open spaces for outdoor activities such as camping and barbecues. Schools are gradually permitting CCAs (co-curricular activities) to resume, and I expect this can be accelerated, especially with paediatric vaccinations gaining momentum."

Prof Paul Tambyah, a senior infectious diseases consultant at the National University Hospital, suggested easing measures that have the most human costs, such as limitations on household visits.

Associate Professor David Allen, an infectious diseases expert at NUS, said that Singapore's high vaccination rate and safe management measures here will likely result in "a modest wave instead of a surge".

Associate Professor Alex Cook, an expert on infectious disease modelling, said: "Even though the Omicron peak is probably not upon us, I think we can roll back many of the measures in place. Especially the silly ones like blocking off half the wash basins in public toilets."

Looking at what is happening elsewhere, Prof Hsu said that data from Denmark, Norway and Britain have been reassuring. Although infection rates have risen dramatically, hospitalisations and deaths have not, particularly among fully vaccinated and boosted individuals.

Similarly, while infections in Singapore are still high here, with more than 3,000 new cases on Wednesday, the number of people seriously ill is low, with 74 needing oxygen and 12 in intensive care units (ICUs).

This year, 31 people have died from Covid-19, fewer than the usual 50 or more deaths a month from influenza.

Prof Ooi Eng Eong, an emerging infectious diseases expert at the Duke-NUS Medical School, said that "the convergence in high rates of vaccine-induced protection as well as a less-virulent variant serves as a unique opportunity for us to implement plans to live with Covid-19".

It is this high protection level from vaccines (89 per cent of the population is fully vaccinated) and booster shots (59 per cent of the population) now that has resulted in a more muted wave of Omicron infections than in countries with lower vaccination rates.

They argued that delaying the easing of measures and missing the current window of opportunity may lead to a larger Omicron wave later as protection against infection wanes in those who received their booster shots early.

Even if more get Covid-19 with the easing of measures, their high antibody levels will likely mean they will be asymptomatic or have a very mild form of the disease, they said.

Singapore started offering booster shots to vulnerable seniors in September last year, pushing up their antibody levels to protect against infection. But these high levels start to wane at around four months, even though protection against severe illness remains.

Prof Ooi said: "We can begin to roll back some of the measures that were necessary when we were either not vaccinated or when our vaccination rates were too low to make a difference."

He said given the way vaccines work, even a new variant that emerges would not be able to cause the devastation that the coronavirus did when it emerged at a time before vaccines were available.

He explained that even when antibody levels from current vaccinations wane, the immune system has memory cells that can be rapidly activated to produce these antibodies as a rapid response to infection. On top of that, virus-specific T cells also rapidly eliminate infected cells and prevent the virus from multiplying.

Unvaccinated still at risk

But Prof Leo Yee Sin, executive director of the National Centre for Infectious Diseases (NCID), took the opposite view, urging for more measures rather than fewer, since there are still vulnerable people here who remain unvaccinated.

Prof Leo suggested there might be a need "to heighten rather than do away with measures" that have proven effective.

This could include reducing the number of people gathering. While vaccination provides the best protection, safe management measures have their value, she argued.

She said that while mild, Omicron still poses risks to those unvaccinated. In Singapore, this includes those eligible but not vaccinated, children between five and 12 years of age who are currently undergoing Covid-19 vaccination, and those below five years old.

Health Minister Ong Ye Kung said last month that there are still 120,000 unvaccinated adults here.

Prof Leo pointed out that Omicron can be spread by people before symptoms appear. "Since there is no way to tell the pre-symptomatic infectious phase, the proven effectiveness of safe management measures should be continued," she said.

"It is not likely that Omicron can be stopped, but we can slow down its transmission to preserve manpower across all sectors."

Prof Dale Fisher, a senior infectious diseases consultant at the National University Hospital, said the threats facing Singapore have changed.

He noted that until recently, the concern was that severe cases could overwhelm the ICUs in Singapore, and indeed the large number - although a small percentage - of unvaccinated adults, especially seniors, did result in pressure on the health system.

That has abated, but new threats have emerged, he pointed out.

Large numbers of mild cases which impact the workforce, including healthcare workers and essential services such as police, food handlers, power, water and sanitation workers, could threaten how the community functions, he said.

He added: "If 5 to 10 per cent of people admitted to hospitals for other reasons have Covid-19 by coincidence, then our isolation capacities could be overwhelmed."

He said there is a need to address the quarantining of contacts and isolation of positive cases as Singapore moves towards endemicity.

Prof Hsu, on the other hand, thinks contact tracing no longer makes sense, given the rapid spread of Omicron and the resulting mild illness that most get.

Experts who argued for the easing of restrictions also pointed to how better treatment is now available.

Prof Allen said that there are now medicines, and more will be coming online, that will reduce the risk of serious illness for many who do not respond to vaccines or are ineligible for vaccination.

Singapore on Thursday approved the use of a drug that significantly reduces severe illness and death if given early.

Future vaccines are also likely to provide broader protection against a range of variants, Prof Allen said.

Dr Sebastian Maurer-Stroh, executive director of A*Star's Bioinformatics Institute, who has been tracking changes in the virus since it emerged, said that more mutations do not necessarily lead to increased severity of the illness.

"Virus evolution will select whatever mutations that make it more successful to keep it circulating," he said.

Prof Fisher said the virus will continue circulating, and this should maintain a level of immunity for most people just as it does for influenza viruses.

For the more vulnerable, such as people with underlying medical conditions, Prof Fisher said continuing research on vaccines and developing them to fight new variants remain important.

Prof Teo said that living with endemic Covid-19 necessarily means the need to increase the resilience of the healthcare system to cope with any inadvertent surges, whether brought about by Omicron or other future variants.

"Otherwise, countries will perpetually be in a limbo state of inaction. Singapore has put in place the necessary preparations, both on the infrastructure and on the manpower front, to prepare for possible surges in hospitalisations."

Prof Cook added that given the rapid spread of Omicron, "it is quite plausible that most people here will be infected over the next few months".

"If you are young and unvaccinated, the risk of serious illness is pretty low.

"If you are elderly though, being unvaccinated is quite a gamble."