Booster vaccine shots being studied by expert committee

Booster shots of the Covid-19 vaccine are being studied, while a third dose is being considered for those who have severely compromised immune systems, said the multi-ministry task force on Covid-19 yesterday.

Health Minister Ong Ye Kung, who co-chairs the task force, said: "We will very likely have to start a booster exercise. (Other) countries started vaccinations earlier than us, and we therefore now have the advantage of observing them and learning from their experiences."

He added that the Expert Committee on Covid-19 Vaccination here is actively working on the booster programme, and studying the results from other countries before finalising recommendations.

He noted that Israel has started administering booster shots to their seniors and the vulnerable.

Meanwhile, Britain, Germany and France have announced that they will start their booster shot roll-out next month.

The United States Centres for Disease Control and Prevention (US CDC) has also just recommended booster shots for those who completed their vaccinations at least eight months ago.

But one thing that the expert committee is clear on and will recommend is that Singapore will proceed to administer a third shot for patients who were severely immunocompromised at the time of their first two doses, Mr Ong said.

Some examples are transplant patients, those on immunosuppressive therapy or cancer treatment, and end-stage kidney disease patients on dialysis. "Because of their conditions, these persons react much less to vaccination, even after two doses, meaning they cannot produce as much antibodies or activate the necessary mechanisms to fight the virus," he said.

"Hence, a third dose of vaccine is necessary for them. The expert committee will be putting out their recommendations on this group shortly."

According to the US CDC website, this additional dose is intended to improve immunocompromised people's response to their initial vaccine series and is not the same as a booster dose, which is given to people when the immune response to a primary vaccine series is likely to have waned over time.

In the meantime, the expert committee is studying the incidence of adverse reactions from a booster shot in other countries.

"Will it be as low as the first and second dose, or higher? And if it's higher, what are the steps that we can take to mitigate or remove the risk?" Mr Ong said.

The committee is also looking into the issue of using the same vaccine or a different one.

There is a scientific basis for suggesting that using a different vaccine may confer stronger protection, he said, adding that Britain is implementing such a strategy and that the committee will be monitoring the outcome closely.

He noted: "In Singapore, too, we have a sizeable group of people who took the first shot of mRNA (vaccine), found out that they are allergic to it, and therefore completed their vaccinations using Sinovac.

"So the committee will be closely monitoring their immune response."