Despite early global data on heterologous vaccinations, he said it was still inconclusive for the government to give the green light for mixing vaccines.

In a joint press conference with health minister Dr Adham Baba today, Khairy said those who got AstraZeneca as their first dose would be receiving the same for their second dose.

“We will continue to study it and once a decision can be made, then we will make an announcement. But for now, you will be given the same second dose as your first dose,” he said.

An Oxford study, which compared mixed two-dose schedules of Pfizer and AstraZeneca vaccines, found that they produced higher concentrations of antibodies against the coronavirus spike protein with either combination.

Some European countries have also begun to offer alternatives to AstraZeneca as a second shot, after the vaccine brand was linked to incidents of blood clots.

Meanwhile, Khairy said a new interval between doses for all AstraZeneca recipients will be announced tomorrow.

He added that all the vaccines being administered in Malaysia, namely Pfizer, Sinovac and AstraZeneca, were still effective against the Delta variant.

“Whatever vaccine you are offered, please take it. It will protect you against variants of concern (VOCs).”

With regard to reports of the Pfizer vaccine triggering rare heart inflammations, Khairy said its side effects were still being monitored in Malaysia.

While the matter would not change the government’s procurement plans for Pfizer, it could affect the decision to roll out the vaccine for teenagers. Further discussions on this will be brought up in a meeting with education minister Radzi Jidin soon, he added.

He also said the police would be setting up a special unit to work with the Covid-19 Immunisation Task Force (CITF) to investigate allegations of illegal vaccine sales and appointments.