Delaying 2nd dose of shot won't affect overall protection, says Health Minister
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People at the Covid-19 vaccination centre at Hong Kah North Community Club in March. So far, 1.4 million individuals here have had both doses of the vaccine. Another 600,000 have had one dose, and they can get their second as scheduled. But they can also volunteer to push back their second dose so that others can have their first dose.
ST PHOTO: LIM YAOHUI
To vaccinate as many people against Covid-19 as possible - and to do this as soon as possible - Singapore has decided to delay the second dose of the vaccine by two to five weeks.
This means that the interval between the first and second jabs will be extended to six to eight weeks, from the current three or four weeks.
This will allow 400,000 more people to get at least one dose without materially affecting the eventual overall immune response, as long as the second dose is eventually administered, said Health Minister Ong Ye Kung yesterday.
When the Health Sciences Authority approved mRNA vaccines for use here, the doses could already be given six weeks apart.
Singapore's Expert Committee on Covid-19 Vaccination said in a press release yesterday: "This is based on the maximum dosing interval that was adopted during the pivotal trials."
The first dose of the mRNA vaccines used here gives about 75 per cent protection 12 days after it is given. This goes up to about 95 per cent with the second dose.
Referring to a study in Britain, the committee said that "based on early evidence in persons aged above 80, such a delay of the second dose to 12 weeks resulted in higher antibody levels two weeks after the second dose".
Asked how the decision was reached to extend the interval between doses, the Ministry of Health's director of medical services Kenneth Mak said there are still some issues to be resolved about having a longer interval.
"Across different jurisdictions, different countries, we seem to be coming to some form of agreement independently that it is acceptable to lengthen the dosing interval," he said. "But it would probably be somewhere around the region of six to eight weeks, which would be reasonable for us to anchor on at the onset."
The committee said that "given the nascent data... a cautious extension of the interval between the first and second dose to six weeks is unlikely to be an issue".
It also indicated concern if the delay were beyond eight weeks.
Singapore's vaccine roll-out is constrained by the delivery schedule. While the Republic has bought enough vaccine doses for all residents here, how fast they can get into arms will depend on how fast the vaccines arrive.
Mr Ong said extending the interval between jabs will give "priority to the first dose so that we cover as big a proportion of our population as possible".
With the longer interval between doses, another 300,000 people can get their first dose this month, with 4.7 million, or almost all eligible people, getting at least one dose by August.
Said Mr Ong: "Altogether, we will be able to reach 4.3 million vaccinated individuals by the end of July. Status quo, we would have reached 3.9 million."
So far, 1.4 million people here have received both doses. Another 600,000 have had one dose, and they can get their second dose as scheduled.
But Mr Ong urged: "Those who have booked but (are willing to) volunteer to push back your second-dose appointment so that... dose can be given to someone else for their first dose, please do so.
"You can call our vaccination call centre on 1800-333-9999. So you can do that and you will do another Singaporean a favour."
