Lim Chee Han, an infection biologist and senior researcher with the Malaysia-based policy group Third World Network, said the incidents were particularly noteworthy given reports that some of those tasked with administering vaccines were selling jabs on the black market.

“There are three incidents that were reported and one even provided video evidence, so this had led to further decline in public confidence and it indirectly increased public suspicion about getting vaccinated,” Lim said.

“I must say that the vaccinators are all human, they could make mistakes given the amount of volume they must handle for a given period at the height of the vaccine roll-out campaign,” Lim said.

“But both sides should ensure they follow the standard operating procedure including observing the syringe content before and after because this can boost confidence given such incident reports surfacing.”

Three cases have emerged in public since the first incident occurred last Saturday at a drive-through vaccination centre set up for armed forces personnel and their families in the state of Kedah, in northern Peninsular Malaysia. In relation to this particular incident, the CITF said a probe was launched by the armed forces which led to disciplinary action taken against a staff member.

Two more incidents of residents purportedly being administered jabs with empty syringes have since surfaced – one at the Malaysia International Trade and Exhibition Centre in Kuala Lumpur on Saturday and another at the Bangi Avenue Convention Centre in Selangor on Sunday. Police reports have been lodged over those incidents and investigations are under way.

The CITF said in its statement that it is standard operating procedure for vaccination staff to show residents being administered jabs that the syringes were filled before the injection. It also urged the public to be attentive that the right dosage was administered.

On social media, some members of the public expressed alarm at videos showing instances of impropriety.

“The number of videos going around is worrying, clearly showing empty syringe/plunger not pressed. Even one oversight is bad. Imagine getting the vaccine certs but not having the vaccine. Hopefully remedied asap,” wrote Twitter user GayathryV.

Another Twitter user, Andrew Jason, meanwhile shared his positive vaccination experience. “I was at [Putra World Trade Centre] yesterday and the doctor who injected me was a real pro, showed me the syringe filled with 0.5ml AstraZeneca dose. Explained the whole process of injecting me and showed me the empty syringe. I wish I could see them filling the syringe up from the [vial] though but happy overall.”

Claims of underdosing and empty syringes have circulated since the roll-out of Malaysia’s national vaccination campaign began on February 24.

Two earlier claims of double injections arose after an elderly woman and a man said they had to receive a second vaccination because their syringe was empty on their first appointment.

The government has said it hopes for a full reopening of the economy in November, when it forecasts the daily caseload will drop below 500 and around 60 per cent of the country’s 33 million people will be fully vaccinated.

Daily infections remain above 10,000 after record highs of over 13,000 last week. On Tuesday, Malaysia reported 12,366 new cases and 93 deaths.

A dramatic recent rise in vaccinations, with 400,000 jabs now being administered daily, has offered hope that the situation can be brought under control soon.