Those who had taken a Moderna booster shot after two doses of Pfizer-BioNTech saw a further reduction in infection risk by 72 per cent, while those who took a Pfizer booster shot after two jabs of the Pfizer vaccine saw a 62 per cent reduction.
The statistics was shared by Health Minister Ong Ye Kung on Monday evening (Nov 15) at a virtual press conference held by the multi-ministry task force on Covid-19.
He said that the Health Ministry had recently done a study on the relative effectiveness of Pfizer and Moderna vaccines as booster shots in terms of reducing infection risk, and compared the two combinations.
One possible combination is three consecutive shots of the Pfizer vaccine (two regular jabs and one booster) while the other combination is a Moderna shot after two regular doses of the Pfizer jab. Mr Ong noted that results for other combinations, such as a Pfizer shot after two doses of Moderna jabs, do not have large sample sizes and hence may not yield meaningful statistics.
Mr Ong and Singapore’s director of medical services Kenneth Mak both took the Moderna shot after two jabs of the Pfizer vaccine.
Mr Ong also explained why Singapore’s reported vaccine coverage of 85 per cent appears to be lower than the reported figures in some other countries.
“This is because some countries report vaccine coverage against the eligible population, whereas we report vaccine coverage against the total population,” he said.
This means that of the remaining 15 per cent who are not vaccinated, 1 per cent of them are not living in Singapore, 9 per cent are children below 12 and not eligible, and the remaining 5 per cent are eligible but chose not to be vaccinated, he added.
“So if we recalculate this based on eligible population, we are around 94 per cent vaccinated. It is one of the highest coverages in the world. MOH will provide both figures henceforth in our daily press release to give a fuller picture of the progress of our vaccination exercise,” Mr Ong said.
This article was first published in The Straits Times.