Bivalent vaccine gives stronger and broader protection against all Covid-19 strains

SINGAPORE – While the XBB strain of Covid-19 which is fuelling the current wave of infections here might be milder, it is still important for people at higher risk to get their second booster shot, said Health Minister Ong Ye Kung on Saturday.

Singapore has just started offering the Moderna bivalent vaccine to people aged 50 and older as a second booster shot on Friday. Their previous jab must be at least five months ago.

This Moderna vaccineprotects against the original wildtype virus as well as the BA.1/2 strains. And the XBB is an offshoot of the BA.2 strain.

Director of medical services Kenneth Mak said that protection against infection “is a little bit stronger after the bivalent vaccine compared to the monovalent vaccine”.

Elaborating on this, he said the bivalent vaccine also expands the range of antibodies against all variants, giving better protection.

The Ministry of Health (MOH) had said earlier that the bivalent vaccine gives an antibody response against Omicron that is 75 per cent better than the original mRNA vaccine.

Mr Ong, speaking at a press conference on Saturday on the surge in Covid-19 cases here, said Singapore is seeing a new wave that is expected to peak in mid-November with as many as 15,000 daily cases.

He said protection against infection is strongest within the first three to four months after vaccination or infection, and there is some protection for up to 10 months – but it does not last forever. However, protection against severe illness remains.

He added: “If you get your minimum protection, meaning three mRNA doses, our data shows that your protection against severe illness, if you’re a young person, is still very strong.”

This is why priority for the bivalent vaccine is for people at higher risk, generally those aged 50 and older who already suffer from some medical problem, such as diabetes or high blood pressure.

Pointing to the usefulness of vaccines and boosters, Associate Professor Mak said that among people aged 60 and older with severe Covid-19 – which means they require oxygen, are in intensive care or have died – the proportion is:

– 7.4 per cent among those not fully vaccinated;

– 5 per cent for those fully vaccinated but have not had a booster shot; and

– 1 per cent for those who have had booster shots.

“So you can clearly see that even if you had a minimum of protection through completing your primary vaccination series, there’s still a protection advantage against severe infection if you proceed and continue on with your boosting,” he said.

The bivalent vaccine is available at the nine Joint Testing and Vaccination Centres. Mr Ong said if the demand for the vaccine is strong, these centres may open on weekends.