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COVID-19 Booster Dose: What You Need to Know!

Are your family members or you eligible for booster dose but still deciding whether or not to get it? If so, this article is for you.

1) I’ve received 2 doses of COVID-19 vaccine, so why do I even need a booster dose?

Recent studies have shown that the immunity against COVID-19 that we obtain from vaccination as well as natural infection wanes over time. This means your risk of getting breakthrough infection will increase as months go by.


For example, studies suggest that Sinovac vaccine efficacy against infection drops from 76% to 28% while Pfizer vaccine efficacy declines from 89% to 68% within three to five months after completion of the second dose.1 Several studies have also shown reduction in immunity among those who have acquired natural infections.2WHO-2019-nCoV-Sci-Brief-Natural-immunity-2021.1-eng.pdf


This waning of immunity needs to be countered by a booster dose and studies have shown that getting the additional dose is effective in keeping immunity at an optimal level:


Thus, getting the booster dose will increase your immunity and provide you with optimal protection against COVID-19.

2) I was infected with COVID-19 and went on to get two doses of the COVID-19 vaccine. Do I still need a booster dose?

If you have been infected and chose to also receive and complete your primary doses of COVID-19 vaccine, it means that you have built a “hybrid immunity”5 Such immunity provides you with a more robust protection from COVID-19 infection. Studies suggest that individuals who recover from COVID-19 and then receive the first dose of Comirnaty (Pfizer-BioNTech) vaccine go on to develop immunity as high as those who received two doses of the said vaccine. If these individuals then proceed to complete their second dose, their immunity is two times higher than the average immunity of individuals who only receive vaccination.6


However, studies have shown that those who recover from COVID-19 infection can be reinfected and those who complete their primary doses can get breakthrough infections. Among the many factors behind this include the waning of immunity from both infection and vaccination over time. Therefore, it would be best for you to take your booster shot, 1 month after you have recovered from COVID-19, to make sure that you will sustain optimum protection against COVID-19.

3) Scientists are saying that current COVID-19 vaccines might not protect against the Omicron variant. If this is true, what’s the point of getting the booster shot?

It is true that one/two primary doses of COVID-19 vaccine are not enough to confer protection against the Omicron variant. However, studies have shown that a booster dose will increase your protection against the Omicron variant7


  • The Comirnaty (Pfizer-BioNTech) booster dose after two primary doses of the same vaccine increases vaccine effectiveness from less than 40% to 76%.

  • The Comirnaty (Pfizer-BioNTech) booster dose after two primary doses of Vaxzevria (Oxford-AstraZeneca) increases vaccine effectiveness from less than 10% to 71%.


These findings show that the booster dose is required and effective to protect individuals against the Omicron variant.

4) Which vaccine should I get for my booster dose?

Currently, the national drug control authority has approved Comirnaty (Pfizer-BioNTech), Vaxzevria (Oxford-AstraZeneca), CoronaVac (Sinovac) and Convidecia (CanSino) vaccines for use as a booster dose. The Ministry of Health Malaysia recommendations on booster dose are as follow:



Prior to making any decisions and recommendations, the Ministry of Health (MOH) has to evaluate and consider available data and evidence. During the early stages of National COVID-19 Immunisation Programme implementation, evidence to support mix-and-match (heterologous) vaccination was still very limited and ongoing. Therefore, MOH did not recommend mix-and-match vaccination for the two primary doses.


In terms of the booster dose, more evidence is now available. Studies have shown that, depending on the types of vaccine that you receive as your primary dose(s), a heterologous booster dose may provide you with more robust protection against COVID-19:


6) Is it true that WHO and scientists from China have said that it could be dangerous to mix and match COVID-19 vaccines?

In July 2021, Dr Soumya Swaminathan, the World Health Organisation (WHO) chief scientist stated that we were, at the time, in a “data-free, evidence-free zone” when it came to the impact of mixing and matching Covid-19 vaccines and thus, doing so could be ‘dangerous’. This led many to use her words as a basis for rejecting mix-and-match booster doses.


However, she then quickly clarified her remarks on Twitter (July 13), saying that people should follow the advice of public health agencies and not make their own decisions on vaccine mixing or taking additional doses. Since then, studies have shown that ‘mixing and matching’ in terms of the booster dose is not only safe but may also provide more robust protection against COVID-19 infection. Evidence suggests that while adverse events, following immunisation (AEFI) after heterologous vaccination, seem to be more common, they are tolerable, mild and do not raise safety concerns. WHO in its recent interim guidance also supports implementation of heterologous booster dose.8


With regard to claims that scientists in China advise against mixing and matching of vaccine doses, evidence seems to suggest otherwise. For example, Shao Yiming, an epidemiologist with the Chinese Centre for Disease Control and Prevention, who is also part of the China’s COVID-19 vaccines response team said that a mix-and-match strategy could be effective in sparking a stronger immune response.9 However, his team decided to wait for more data before making their recommendation.10 In addition, Zhong Nanshan, a prominent scientist from China, in his statement at the Greater Bay Science Forum, said that countries should be open to mixing and matching shots if the approach works.11

7) Is it true that senior citizens are at risk of post-vaccination death, especially after getting their boosters?

There is no evidence to support the claim that the booster dose can put senior citizens at risk of post-vaccination death. To date (Dec 7), 3,048,396 individuals have received their booster doses and no vaccine-related deaths have been reported.


Studies among 271,747 adults above 50 years old have shown that the booster dose is safe and effective. Among recipients of two primary doses of Vaxzevria (Oxford-AstraZeneca) and two primary doses of Comirnaty (Pfizer-BioNTech), protection against symptomatic COVID-19 infection increased to 93.1% and 94.0% after receiving the Comirnaty booster dose.12


The booster dose is very important for senior citizens due to alteration in their immune system (immunosenescent). Not only are older people at greater risk of severe illness and death if they develop COVID-19, but their immunity may also not peak as high, as well as wane more rapidly post-vaccination when compared to younger adults.13

8) Does Pfizer booster dose cause more serious side effects compared with Sinovac?

In general, regardless of the types of vaccine received, side effects after COVID-19 vaccination vary between individuals. There is currently no evidence to suggest that the Comirnaty (Pfizer-BioNTech) booster dose will result in more serious side effects as compared with the CoronaVac (Sinovac) booster dose. A study of 2,878 booster dose recipients has shown that the local and systemic reactions from Comirnaty or CoronaVac injections were similar, with fatigue and headache as the most common systemic reactions and pain as the most frequent local reaction, with none of these resulting in death.14

9) Is the booster dose safe for people with chronic diseases?

Yes, the booster dose is not only safe but also highly recommended for individuals with chronic diseases including heart disease, cancer, and diabetes.


Until November 1, booster doses have been given to 8.1 million people in the UK, including individuals with chronic diseases.15 Based on available data, COVID-19 vaccine side effects in those with fragile immune systems appear to be the same as those in healthy individuals.16 These side effects are moderate and transient, while severe side effects are extremely rare.


Chronic disease patients need booster doses due to various factors. Firstly, the immunity post-vaccination may not peak as high among some patients due to a weakened immune system or treatment. For example, cancer therapy can reduce the robustness of vaccine response.


Secondly, immunity, post-vaccination, also wanes over time. For example, protection from Sinovac vaccine drops from 76% to 28%, while protection from Pfizer vaccine declines from 89% to 68% within three to five months after completion of the second dose.17


Studies have shown that Comirnaty (Pfizer-BioNTech) booster vaccine effectiveness (VE) are similar for those with and without comorbidities:18


  • 93% against risk of COVID-19-related hospitalization,

  • 92% against risk of severe COVID-19 disease


Patients with chronic diseases are encouraged to consult their doctors prior to receiving the booster dose. Any adverse events following immunisation (AEFI), should be reported through their attending doctor.

10) I wish to get my flu vaccination. Is it safe to have it around the time I get my COVID-19 booster shot?

Yes, it is safe to get the COVID-19 booster and the flu vaccination around the same time.


The World Health Organisation (WHO) recommends member countries to consider administering COVID-19 vaccines and influenza vaccines during the same visit to encourage higher uptake of both vaccines.19


However, the Ministry of Health Malaysia recommends a fourteen-day interval between receiving the COVID-19 vaccine and any other vaccine. For example, if you are due to receive your COVID-19 vaccine on the 15th of the month, you may get any vaccine, including your flu shot, on the 1st or the 30th of the same month.

11) For how long will the protection from COVID-19 booster dose last?

Currently, it is too early to tell how long the immunity from a booster dose will last. More evidence will surface over time. Nevertheless, a study by Northwestern University, in the United States, found that antibody response is higher after the booster dose compared with after the second dose of Comirnaty (Pfizer-BioNTech) vaccine.20


The study also suggests that protection may also last longer.

12) Do we still need to wear masks and follow the SOP after vaccination and booster doses?

Vaccination (including the booster dose) reduces the risk of infection and severe disease but does not offer perfect protection. As such, we still need to continue to follow public health regulations and safety measures, such as mask wearing, safe distancing and good hand hygiene. This is so we can continue to protect ourselves and our loved ones.

13) How can I have my preferred vaccine under the Ministry of Health’s free booster dose programme?

Under the National COVID-19 Immunisation Programme-Booster (PICK-B), only Comirnaty (Pfizer-BioNTech), Vaxzevria (Oxford-AstraZeneca), CoronaVac (Sinovac) and Convidecia (CanSino) are offered for the booster dose. When it is time for you to receive a booster shot, you will be notified via MySejahtera regarding the date, time and assigned vaccination centre (PPV).


Most PPV centres will be offering the recommended Pfizer booster. However, if you have strong preference or, for medical reasons, require a different booster vaccine from the one offered to you, please inform PPV centre personnel. If the PPV does offer the alternative vaccine, they may be able to accommodate your request on the day itself, or place your name on the waiting list for the desired vaccine. If the PPV you are assigned to does not offer your vaccine of choice, you may check with other nearby PPVs that are registered with ProtectHealth. These PPVs are listed at the ProtectHealth website:

14) Where can I refer to for reliable information about the booster dose?

You may get the latest update on National COVID-19 Immunisation Programme – Booster through: