Few are left to inoculate in wealthy Singapore after a vigorous campaign achieved a level of coverage envied by many nations battling the coronavirus pandemic, but a record surge in deaths and infections gives warning of risks that may still lie ahead.
Despite mask mandates, strict social curbs and COVID-19 booster doses available for over a month, infections in the Asian city-state's latest outbreak, driven by the Delta variant, took the death toll to 280, up from 55 early in September.
"Singapore may potentially experience two to three epidemic waves as measures are increasingly relaxed," said Alex Cook, a disease modelling expert at the National University of Singapore (NUS).
"Until then, deaths will probably continue to rise, unless many of the residual unvaccinated elders can be vaccinated or more get their booster shot."
Cook expects the current wave to subside as the population builds up immunity, with most infections mild enough for recovery at home.
Singapore is one of several so-called COVID-zero countries that enforced some of the world's strictest measures to hold infections and deaths far below the tallies elsewhere.
That was part of a strategy of waiting until a vast majority of its 5.5 million citizens had been vaccinated before gradually easing curbs and resuming more economic activity.
Now it is slowly re-opening its borders, expanding quarantine-free travel to nearly a dozen countries. Australia and New Zealand have begun a similar transition, while China has yet to move ahead.
But the question authorities face is how to avert surges among older people and those with weak immune systems, particularly after the fast-spreading Delta, which arrived in Singapore this year, became the most dominant strain globally.
"If I were a policymaker in Australia, New Zealand or China, I'd be studying what has happened in Singapore," Cook said.
Although 84% of Singapore residents have been fully vaccinated, most with doses from Pfizer (PFE.N)/BioNTech or Moderna (MRNA.O), the vaccines may not protect some of the most vulnerable.
Fully vaccinated people made up about 30% of deaths over the last month, most older than 60 with underlying medical woes, in line with studies showing that vaccines offer less protection to the old and very ill. read more
But Singapore's rolling seven-day average of 1.77 daily deaths per million people outstrips regional peers such as Japan with 0.14, South Korea with 0.28, and Australia with 0.58, the website Our World in Data shows.
It trails the U.S. figure of 4.96, and Britain's 1.92.
Yet cumulative deaths as a share of population still rate among the world's lowest, at 47.5 per million. That compares with figures of 2,825.7 in Brazil and 2,202.4 in the United States.
