KUALA LUMPUR – Receiving a Covid-19 vaccine less than the recommended dosage will reduce its efficacy, according to a health expert, as concerns are raised over recent reports of individuals not given the required dosage.
Thomson Hospital Kota Damansara emergency services head Dr Mohamed Al-Hadi Mohamed Razhi said it is important that the correct amount of vaccine dose be administered for it to have the required effect.
He added that manufacturers have conducted stringent scientific studies and tests before recommending the optimal dosage.
“A vaccine is like any other drug and medication. You need to use a certain dosage to have the desired effect,” he told The Vibes today.
“For instance, if you take paracetamol and consume less than the recommended 1g, it won’t be as effective. It’s the same with a vaccine.
“If the manufacturer recommends a certain dosage and you give less than that, the efficacy of the vaccine will definitely be reduced, or it may not be effective at all.”
Dr Al-Hadi was commenting on reports that a couple of Malaysians, who recently got their first AstraZeneca jab, received less than the required 0.5ml dosage.

Both individuals posted videos of their shots on Twitter, showing them receiving only about 0.1ml of the Covid-19 vaccine. After lodging a complaint, one of them was later given an additional 0.4ml.
While the Covid-19 Immunisation Task Force said it is investigating the two cases, the extent of the issue has yet to be determined.
Checks on social media found that several others have similarly claimed to have received a lesser amount of the vaccine, but did not take videos of their vaccination process.
If these claims are true, it raises the concern that many more Malaysians who have taken the first jab may not get the full benefit of the vaccine, leaving them still vulnerable to Covid-19 complications.
Dr Al-Hadi said it is vital that those who did not receive the full dose be given the recommended amount, although identifying such individuals may be difficult.
“For me, if it is proven that the received dose is less than recommended, I will take it as the person not receiving any dose of the vaccine and start the process all over again.”
For individuals who have yet to be vaccinated, the health expert advised them to check with the personnel administering the jab that the dosage is per recommended.
“As a patient, if you have any doubt, you have the right to check and clarify. There is no problem.”
Other than AstraZeneca, the other two approved vaccines in Malaysia are Pfizer-BioNTech and Sinovac, which require 0.3ml and 0.5ml per dose, respectively. – The Vibes, May 22, 2021