Those in their 50s are set to receive either the Moderna or Pfizer vaccine when their inoculation begins next week amid an anticipated delay in deliveries from Moderna. 

The state task force on vaccination said on Monday that due to the "fluid situation" regarding vaccine supply, the government has decided to use the Pfizer vaccine to some of those in the age group, with the first shots of the Modern vaccine set to kick off next Monday. 

The task force said although there is no change in the combined supply of vaccines for July and August, most of the Moderna shots for July delivery are expected to arrive in late July. The Pfizer vaccine to be administered to those in their 50s has been kept in store by the government for use in August. 

The task force will also extend the last day of vaccination for those aged 50 to 59 by three days from August 25 to August 28 to guarantee the stability of the forthcoming vaccination session. 

Around seven-point-four million people are presumed to be eligible for the vaccines earmarked for the session.