If all goes well and there are no disruptions to the supply, one million more people would have received shots by April.
Some 250,000 Singapore residents have been vaccinated to date, with around 110,000 having received their second dose, Gan added.
The aim is to get another one million people to take their first dose of the vaccine by early April, added Education Minister Lawrence Wong, who co-chairs the task force tackling the pandemic with Mr Gan.
"If all goes according to plan, then we can progressively roll out to the other age groups beyond March," said Mr Wong. "We will continue to monitor the supply of vaccine, because that's the critical issue that will enable us to get vaccines out... We will try our best to ensure that we can get these vaccines to Singapore."
The ministers were speaking to reporters at a vaccination centre at Jalan Besar Community Club. The centre began operations on Thursday (Feb 18), and is open daily from 8.30am to 10pm.
The Health Ministry said that Covid-19 vaccination for seniors aged 70 years and above will start on Monday (Feb 22), following a pilot for those living in Ang Mo Kio and Tanjong Pagar.
More than 5,000 seniors from both towns have received their vaccinations.
Over the next three weeks, others in that age group can expect to receive letters inviting them to sign up for vaccination.
Gan noted that Singapore currently has 11 vaccination centres in operation, with three more slated to open next week. More than 30 centres will be up and running by the middle of March, with the full complement of around 40 centres to be in full swing by end April.
He said: "We will watch the progress and if need be, we will open up additional vaccination centres to cater to the needs of the population."
The Covid-19 situation is also getting much better in Singapore. There were only 11 Covid-19 cases reported on Sunday (Feb 21) - all imported and placed on stay-home notice upon arrival here.
They bring Singapore's total to 59,869.
There are no new cases of locally transmitted Covid-19 infection, said the Ministry of Health (MOH).
Singapore has had 29 deaths from Covid-19 complications, while 15 who tested positive died of other causes.
Globally, the virus outbreak, which began in December 2019, has infected more than 110 million people. More than 2.4 million people have died. - The Straits Times/ANN