[EXPERT REACTION] Should I be worried about the brands of COVID-19 vaccines I take?

(Photo: Nataliya Vaitkevich/Pexels)


By Tan Su Lin & Jenny Wong

Malaysia rolled out its National Covid-19 Immunisation Programme on Feb 24. While the clock is ticking to get more people inoculated to achieve 80% herd immunity in the Malaysian adult population, we asked 2 experts, Dr Khayriyyah Mohd Hanafiah, Microbiologist & Senior Lecturer at Medical Microbiology, Universiti Sains Malaysia and Dr Tommy Tong, Immunologist & Senior Lecturer at the Department of Biological Science, Sunway University to answer some of our burning question regarding the COVID-19 vaccine:

1. Should I be worried about the brands of COVID-19 vaccines I take? 

Dr Khayriyyah Mohd Hanafiah, Microbiologist & Senior Lecturer at Medical Microbiology, Universiti Sains Malaysia, said:

It is difficult to truly compare the performance of different vaccines because they were all tested separately, in different trials. Although we don’t know how well different vaccines protect people from ever getting infected with the virus, what is clear is that any one of the COVID-19 vaccines will protect you from getting severely ill if you get infected, even if you are older than 65, or have other conditions that make you more likely to get very ill from COVID-19.

Dr Tommy Tong, Immunologist & Senior Lecturer at the Department of Biological Science, Sunway University, said:

In general, one should not be too worried about the brands of vaccine. The purpose of the vaccine is to boost the immune system to combat against an infectious agent. If there are health concerns (for example: individuals with pre-existing medical conditions), please disclose this information to the physician or doctor before taking a particular vaccine. 

2. Am I completely protected if I am vaccinated? 

Dr Khayriyyah:

Nothing can ever completely protect anyone. A vaccine is an important, quick and effective strategy to strengthen your immune system. If you can boost your ability to fight off an infection (through a combination of vaccination, healthy nutrition, exercise) and reduce your risk of being exposed to the virus then you will be more protected from getting sick. Our brave healthcare workers are at the forefront of the epidemic, and they are more likely to get exposed to the virus especially while case numbers are still high. Although vaccination did not prevent them from getting infected, the vaccines protected them from getting severe symptoms.

3. Can you spread Covid after being vaccinated?

Dr Khayriyyah:

Early data from the mRNA vaccination shows effectiveness of 90% (for complete two doses), and 80% (for one dose) in preventing infection (https://www.cdc.gov/mmwr/volumes/70/wr/mm7013e3.htm?s_cid=mm7013e3_w). This means the mRNA vaccines can significantly reduce the risk of a vaccinated person from spreading the virus, even if it doesn’t block the infection or transmission completely (again, nothing is perfect!). 

The data for other vaccines is still not available but it is likely they also reduce transmission, at varying levels of effectiveness. This gives us hope that in time with more people vaccinated (with any vaccine), we can both control the severity of COVID-19 disease, while getting a majority of people immune to the virus.

Dr Tommy:

It is true that COVID-19 vaccination has shown to induce protective antibodies in humans in various clinical trials (Yan et al, 2021; https://doi.org/10.3390/ph14050406). However, the question whether vaccinated people can transmit the virus, even though they do not display any symptoms remains to be addressed. 

This is because SARS-CoV2 virus typically enters the body through our nasal cavities (aka nose). Vaccinated individuals may still carry enough virus in the nose to infect others through breathing or sneezing. Scientists are studying whether the vaccinated individuals produce enough antibodies in the nose area to prevent the virus from growing. This is one of the reasons to continue to wear masks after vaccination.

4. Can COVID-19 vaccines give you a blood clot? And are women more likely than men to be affected by blood clots?

Dr Khayriyyah:

So far there are a small number of individuals vaccinated with the adenovirus vectored vaccines such as those developed by AstraZeneca and J&J (in the hundred millions of vaccine doses given) have developed blood clots. To be specific, in the UK there were 30 individuals reported with different forms of blood clots after being vaccinated with the AstraZeneca vaccine, after 18.1 million doses of the vaccine was administered. There are some concerns about women and younger people being more at risk, but the data is still patchy at the moment. The higher number of women among those who have post-vaccination blood clots may also be because most people vaccinated at this phase are healthcare workers, a majority of whom are women. The situation is being urgently investigated to find a way to better manage this potential risk, but this is a very rare side effect and the overwhelming majority of people have been safely vaccinated. 

5. Should I get Covid vaccine if I have Covid-19?

Dr Khayriyyah:

While getting sick with COVID-19 may give some immunity, the vaccines are designed and thoroughly studied to give special training to the immune system so that there is better immune protection. Even if someone has recovered from COVID-19, if they are eligible and have access to the vaccine it is a good idea to get vaccinated to boost protection.

Got any burning questions? Email us at info@sciencemediacentremalaysia.com and we will get our experts to answer them! 

*This Expert Reaction is part of the “Yakini Vaksin” campaign in collaboration with The Petri Dish which aims to debunk COVID-19 vaccine myths and misconceptions. This campaign is supported by Malaysian pharmaceutical company, Duopharma Biotech Berhad as part of its corporate social responsibility initiative. 

**All previous posts about COVID-19 here: https://sciencemediacentremalaysia.com/tag/covid-19/

Bionotes of experts

Dr Khayriyyah Mohd Hanafiah is a senior lecturer in Medical Microbiology at Universiti Sains Malaysia, and an affiliate of Young Scientists Network-Academy of Sciences Malaysia. She is active in science communication and infectious disease biomedical research. She was the first female Asian champion of FameLab, the world’s longest running science communication competition, in 2018. 

Dr Tommy Tong graduated from Monash University, Australia with a PhD in Immunology. He was working on vaccine development against human immunodeficiency virus (HIV) for his PhD dissertation, before joining Professor James Binley at San Diego for Biomedical Research (SDBRI) in the U.S. to continue his passion in HIV research for 4 years. He is now a lecturer at the Department of Biological Science, Sunway University, and has started his own laboratory to work on HIV vaccines for Malaysians. 

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