Singapore has reported its highest one-day Covid case total in more than a year, with 837 cases recorded on Tuesday.

In response to the growing outbreak, the government has paused reopening plans and reimposed some restrictions.

As of Tuesday, a total of 809 people were in hospital. Of these, 75 were seriously ill and required oxygen, and nine were in intensive care. The majority of seriously ill patients were older than 66, according to the Ministry of Health.

Eighty-one per cent of the entire population is fully vaccinated – excluding under-12s, it is 90% – and the number of seriously ill patients is fairly low overall. Just four people have died in the past 28 days, all of whom were unvaccinated, according to the health ministry.

However, the number of those seriously ill is increasing. The number of patients requiring oxygen doubled to 54 on Sunday from two days before, an important gauge to judge whether the medical system could get overwhelmed.

Update on COVID-19 situation (14 Sep 2021):

We have detected two new clusters at 11 Tuas Ave 10 dormitory and All Saints Home (Jurong East), which have been ringfenced through active testing.

For the full details: https://t.co/iIYxsPwXiT pic.twitter.com/fmPSHT4cP9

— Ministry of Health (@sporeMOH) September 14, 2021

“Over the last 28 days, the percentage of local cases who were asymptomatic or had mild symptoms is 98.1%. Of the 114 cases who required oxygen supplementation, 56 were not fully vaccinated and 58 were fully vaccinated. Of the eight who had been in the ICU, five were not fully vaccinated and three were fully vaccinated,” the ministry wrote in its update on Tuesday.

Lawrence Wong, finance minister and co-chair of the coronavirus taskforce, said last week that a key indicator in determining reopening moves would be the number of patients in intensive care units over the next two to four weeks.

At present there are 300 ICU beds available, which could be increased to 1,000. If numbers stay manageable, the country will resume reopening plans, he said.

The health ministry also banned social gatherings at workplaces in response to clusters detected in staff canteens.

The new outbreak is being watched by other countries that have managed to keep case numbers relatively low throughout the pandemic. Australia’s prime minister said in July that an 80% vaccination rate (of the eligible population – not the total population) would herald the end of statewide coronavirus lockdowns.

Dale Fisher, a professor at Singapore’s National university hospital who specialises in infectious diseases, told the ABC on Monday that cases were “by and large very mild” in immunised Singaporeans.

“We’re sort of feeling our way, but clearly you can’t just open the gates and say the vaccine will look after us. It needs more than that,” he said.

“In Singapore it’s really about the people just getting more comfortable with the case numbers and realising that increasing case numbers does not translate to significantly increased numbers in hospitals and severe disease and deaths,” he said.

“Obviously you’ve been telling the public for a year-and-a-half now: ‘Don’t get Covid’,” but now vaccinations meant “We’re singing a different song” and trying to slow infections.

He added that though vaccination rates were high, at least 500,000 people were still unvaccinated, which can “put a dent in your health system”. Australia would have the same concerns when it achieved 80% vaccinations, he said. The state of New South Wales, which is the centre of Australia’s current outbreak, achieved an 80% first-dose rate on Wednesday.

In China, Putian, a city of 3.2 million, ordered testing of all residents on Tuesday after Delta variant cases linked to a returnee from Singapore ballooned into a province-wide outbreak of more than 100 people.

Singapore is now considering a third shot for younger adults and may start inoculating children early next year. This week it will start boosters to elderly people and immunocompromised groups.

“If by offering booster shots to the people, including young adults, Singapore is able to relax its restrictions quicker especially with respect to reopening Singapore’s borders, then this may be an existential decision that the government is forced to take,” said Teo Yik Ying, dean of the Saw Swee Hock School of Public Health at the National University of Singapore.

– with Reuters