Adding to growing efforts to persuade hesitant seniors to get vaccinated, Prime Minister Lee Hsien Loong yesterday said "don't wait till it's too late".

With 200,000 seniors aged 60 and above yet to receive their jabs, vaccine hesitancy among this vulnerable group has become a key issue amid the latest rise in cases - one that could put pressure on hospital resources and have an impact on the pace of Singapore's reopening.

"Don't worry, it's very safe," said PM Lee about the vaccines in yesterday's Facebook post, recorded in all four of the official languages.

Worries about the vaccine's side effects and long-term safety are the main reasons cited by seniors in avoiding vaccination.

"You may feel unwell for a day or two, but you will be okay. It is just your body building up its immunity against Covid-19," he said.

While around 80 per cent of seniors aged 60 and above have been vaccinated, the number falls to 70 per cent for those 70 and above.

To keep the population safe from Covid-19, it is best for 70 per cent to 80 per cent or more of the population here, including close to 90 per cent of the elderly, to be vaccinated, said Health Minister Ong Ye Kung recently.

PM Lee reminded seniors yesterday that they were at risk of Covid-19 even if they did not go out much, as they could catch the virus from friends or family members, adding that the disease is dangerous for older people, especially for those with medical conditions such as diabetes. "The vaccine will protect you from Covid-19," said PM Lee, 69, highlighting how he had received both his jabs.

His post comes after a sharp rise in infections, with more than 1,000 community cases reported in the past week.

Part of the reason was the virus spreading from the Jurong Fishery Port to dozens of markets, forcing them to be closed.

Mr Ong said then: "Markets are frequented by seniors, many of whom remain unvaccinated. This is most worrying, and we are at risk of an uncontrollable rise in cases, which could potentially result in many severe illnesses or even deaths."

The country also tightened other measures on Thursday, including a ban on dining in at food and beverage outlets.

There has been a concerted push to vaccinate seniors, including giving them priority. PM Lee advised seniors yesterday that they can go to any polyclinic or vaccination centre for their dose without a prior booking - an arrangement in place since June 1.

Mobile vaccination teams have been set up in 10 towns, including Sengkang, Tampines and Yishun, to make it convenient for those who find it difficult to leave their homes.

Senior Minister Teo Chee Hean yesterday posted on Facebook to encourage these seniors to contact the Silver Generation Office, which can provide assistance.

Mr Ong has also called on general practitioners to persuade their older patients to get the jabs.

Doctors told The Sunday Times that some seniors fear the vaccine could worsen pre-existing conditions or trigger an allergic reaction.

Yet these seniors have even more reason to get vaccinated as they are at risk of more complicated health problems if they get infected, said the doctors.

"They may still get Covid-19 after the vaccination, but they are more likely to be asymptomatic or have less serious symptoms. Data has shown that vaccinated people have mild or no symptoms," said Dr Pauline Neow, who runs a clinic in Queenstown, and one in Toa Payoh.

• Additional reporting by Goh Ruoxue