Seven people died from dengue in the first three months of this year and infections have now surged beyond 500 cases a week.
Exposure to dengue has been worsened by people staying and working from home during the Covid-19 outbreak.
The seven who died were aged between 60 and 80 and all had lived or worked within dengue clusters, said the National Environment Agency (NEA).
The Straits Times understands that there have been more deaths since last month.
Twenty people, with ages ranging from 52 to 78, died from dengue last year, which saw the third worst outbreak here with about 16,000 cases.
Some 508 people were infected last week - a jump of 118 cases over the 390 in the previous week. The 7,400 cases so far this year is also more than double that for the same period last year.
The NEA expects the number of infections to stay high, and perhaps even rise in the coming months.
It said on its website: "As we enter the warmer months of May to September, there is usually higher transmission of dengue in Singapore, due to accelerated breeding and maturation cycles for the Aedes mosquitoes and shorter incubation periods for the dengue virus."
It added that with the Covid-19 circuit breaker in force till June 1, more people are working from home and this "increases their exposure to bites by Aedes mosquitoes that can carry the dengue virus". This is especially so if they are living in an area with high mosquito population.
There are 123 active clusters now, with three large clusters having more than 100 infections each.
The biggest is along Bukit Batok Road with 153 infections, mainly at Pavillion Circle. The other two are at Woodleigh (134) and Westwood area along Jalan Bahar (104).
Earlier this month, the NEA said it is releasing male mosquitoes carrying the Wolbachia bacteria that make them sterile, in the Choa Chu Kang and Bukit Batok areas.
Senior Parliamentary Secretary Low Yen Ling, an MP for Choa Chu Kang GRC, was diagnosed with dengue recently.
The females that these male Wolbachia-carrying mosquitoes mate with would lay eggs that will not hatch, thus curbing the expansion of the mosquito population.
Wolbachia-infected mosquitoes have previously been released in Tampines and Yishun areas and have resulted in a 90 per cent suppression of the Aedes aegypti mosquito population. This is the mosquito strain that is primarily responsible for the spread of dengue here.
The NEA also cautioned all businesses and owners of premises to ensure that they have adequate vector control measures at their premises "even if certain operations may be on hold during this circuit breaker period".
It added: "This includes construction sites, offices and commercial buildings, shops, entertainment outlets, nurseries, farms, schools, and places of worship."
In the first quarter of the year, its officers found 4,600 mosquito breeding habitats.