Moderna booster more effective for those over 60 who took Pfizer jab: NCID

The Straits Times

SINGAPORE - A booster shot with the Moderna vaccine offered older people better protection against Covid-19 if they had previously taken Pfizer jabs, researchers at the National Centre for Infectious Diseases (NCID) have found.

Seven days after taking a booster shot, people above the age of 60 who took Moderna had an average antibody level that was twice as high as those who took the Pfizer-BioNTech/Comirnaty vaccine, the study showed.

This was consistent across all variants of concern of the Covid-19 virus, said NCID in a press release on Thursday (March 17).

Dr Barnaby Young, head of the Singapore Infectious Disease Clinical Research Network in NCID, said the aim of the study is to build local data on understanding immunity towards the disease through booster shots.

"The emergence of variants capable of evading protective immunity remains a concern and highlights the need for a long-term Covid-19 immunisation strategy," he added.

Dr Young had co-authored the study which was published in SSRN, a science research journal, on Thursday. It has yet to be peer-reviewed.

The study, conducted between Oct 12 and Dec 3 last year, involved 100 participants who had received the Pfizer shots as their primary series of Covid-19 vaccination.

Half of the participants were above 60 years old.

Researchers observed that even at 28 days after vaccination, average antibody levels in older people remained 1.5 times higher in those who had taken the Moderna booster.

However, in younger adults, antibody levels were similar between the two vaccines.

The study involved blood samples collected 28 days before the booster shot, on the day of the booster shot but before the injection, and seven days and 28 days after the shot.

For those older than age 60, researchers noted that neutralising antibody levels against the Omicron variant with a Moderna booster were at 84.3 per cent 28 days after the shot versus 72.8 per cent with a Pfizer-BioNTech/Comirnaty booster.

Neutralising antibodies are thought to play an important role in immunity against the coronavirus.