SINGAPORE - The first batch of 140,000 SMS invitations has been sent out to seniors who are due for their Covid-19 booster shots, with more invitations expected to be sent out weekly, said the Ministry of Health (MOH).

The ministry also clarified that these seniors, aged 60 and above, can get their booster shots at any vaccination centre, polyclinic, or participating Public Health Preparedness Clinic (PHPC).

Prior booking must still be made, it said. The Straits Times understands that walk-ins have also been accepted.

Singapore kicked off its national Covid-19 vaccine booster programme on Wednesday (Sept 15).

Seniors who completed their vaccination regimen around March this year will be the first in line for the third dose.

They are required to make an appointment via the personalised link in the SMS sent to their mobile number registered for their first two doses.

An MOH spokesman, in assuring the public, said: "The capacity of our vaccination sites are more than enough to cater to the volume."

The ministry is working with the People's Association (PA) and the Silver Generation Office to encourage seniors to go for their booster doses via phone calls or house visits. Seniors may also visit any of PA's community clubs and centres islandwide for help in booking their appointment online.

Those who are immunocompromised have also started receiving their third dose at hospitals and specialist outpatient clinics from last Wednesday, said MOH.

This group of people have been advised to receive their third dose of the same mRNA vaccine two months after their second dose, as this ensures they start off with adequate protective immune response to the virus.

The mRNA vaccines include Moderna and Pfizer-BioNTech.