Thursday 28 Mar 2024
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Confusion over vaccine efficacy and vaccine hesitancy proves to be a major stumbling block in achieving herd immunity in Malaysia.

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KUALA LUMPUR (June 21): Vaccines have been one of the biggest success stories of modern medicine. Over the course of history, vaccination has proven to be one of the most important cost-effective measures for controlling and preventing infectious diseases, being responsible for preventing millions of deaths worldwide every yea. It is based on the pioneering trials of vaccination performed by Edward Jenner and Louis Pasteur. Since these early efforts, vaccines have been developed against important diseases that have affected humanity. The eradication of smallpox, which was considered to be the worst plague of humankind, announced in 1977 by the World Health Organization (WHO), is perhaps the best illustration of the power of this approach. On a more recent note, the WHO also estimates that at least 10 million deaths were prevented between 2010 and 2015 thanks to vaccinations delivered around the world.

Vaccine efficacy & immunity

The duration of immunity (protection against disease) varies with different diseases and different vaccines. Lifelong immunity is not always provided by either natural infection (getting the disease) or vaccination. The recommended timing of vaccine doses aims to achieve the best immune protection to cover the period in life when vulnerability to the disease is highest. Many vaccines used today are relatively new and data concerning the length of time that they give protection is continually being updated. One good example of this is the recently developed Covid-19 vaccines.

We have likely heard that some of the vaccines like Pfizer's Covid-19 vaccine efficacy is 95%, Moderna's is 94% and Johnson & Johnson's is 66% with Sinovac being the least in terms of efficacy with 50.4% (Initial Brazilian trial). But what do these numbers actually mean?

One common misunderstanding in Malaysian public is that 95% efficacy means that in the Pfizer clinical trial, 5% of vaccinated people got Covid. But that is not true; the actual percentage of vaccinated people in the Pfizer (and Moderna) trials who got Covid-19 was about a hundred times less than that: 0.04%. What the 95% actually means is that vaccinated people had a 95% lower risk of getting Covid-19 compared with the control group participants, who weren't vaccinated. In other words, vaccinated people in the Pfizer clinical trial were 20 times less likely than the control group to get Covid-19.

Apart from that, the public CANNOT compare the efficacy rates of all the vaccines head-to-head. For example, one might perceive that the Pfizer and Moderna vaccines are the best due to the 94%-95% efficacy shown and the Astra Zeneca is only showing 76%. The Pfizer and Moderna vaccines were tested before newer, more contagious variants were widespread, making a difference in trials. Apart from that, the public CANNOT compare the efficacy rates of all the vaccines head-to-head. For example, one might perceive that the Pfizer and Moderna vaccines are the best due to the 94%-95% efficacy shown and the Astra Zeneca is only showing 76%. The Pfizer and Moderna vaccines were tested before newer, more contagious variants were widespread, making a difference in trials. They were also tested in a different group of people and environment.

Malaysia currently endorses 3 different brands of vaccines for use in its National Immunisation Programme with the mRNA-based vaccine Pfizer-BioNTech deemed the best followed by the Oxford AstraZeneca and China’s CoronaVac (Sinovac). Comparatively, of the three Covid-19 vaccines currently in use in the government’s National Covid-19 Immunisation Programme (NIP), perhaps one of the more divisive ones is Sinovac’s CoronaVac. On one hand, some view it as an inferior product compared to mRNA vaccines like Pfizer-BioNTech’s Comirnaty due to its poor efficacy in trials, especially when CoronaVac was tested in Brazil and varying efficacies when some of the studies were done elsewhere impacted on the Malaysia public trust on the safety and efficacy of the vaccine. The conversation online is further inflamed by the politics surrounding vaccines and their perceived country of origin, especially for vaccines made in China. There is a fear that anything with a “Made in China” tag lacks quality and safety not to mention fears over the ‘halal’ status among Malaysian Muslims who represents majority of Malaysia and may be decisive in achieving the herd immunity threshold.  

Meanwhile, proponents view it as a safer vaccine because it was manufactured using the tried-and- true method of inactivating viruses (just like majority of previous successful vaccines), as opposed to mRNA vaccines (like Comirnaty) and viral vector vaccines (Oxford AstraZeneca and Gamaleya’s Sputnik V) that are relatively new. 

Public concerns about vaccination amid swirling misinformation

Another setback towards the National Immunisation Programme in Malaysia which contributed towards vaccine hesitancy among the people in rural areas include a silent anti-vax movement via social media platforms such as Facebook and WhatsApp have created anxiety and fear among the public regarding the safety and efficacy of the Covid-19 vaccines. The speed of global information exchange has been significantly boosted by social media, leading to viral sharing of fringe opinions and disinformation. It is thus hard for the public to tell whether something is an established fact, and truth is lost in noise. 

The World Health Organization (WHO) Director-General described this very aptly in February 2020, when he said of Covid-19 before it became a pandemic, “We’re not just fighting an epidemic; we’re fighting an infodemic.” An infodemic refers to an excess of information, some correct and some not, which arises during a disease outbreak. It spreads across populations in a similar manner to a disease outbreak, via digital and physical information systems, making it difficult for people to access reliable information when they need it. The creation of uncertainty is particularly harmful when it comes to vaccination, because doubt causes vaccine hesitancy thus proving as a major stumbling block to achieve herd immunity threshold.

Apart from doubts surrounding the efficacy, components and safety of the Sinovac vaccine among Malaysians, reports of rare events of thromboembolic phenomena in young adults receiving the Oxford AstraZeneca vaccine caused a huge uproar among Malaysians recently prompting the government to temporarily remove it as part of the National immunisation Program initially due to misinformation and lack of vaccine education towards the public on the benefit vs risk, especially when it prevented 100% severe symptoms, hospitalization and death from Covid-19 in vaccinated people and the incidence of blood clot is somewhere around 0.0004%, which is extremely rare.

Vaccine hesitancy & exiting the pandemic

Overall, many compounding factors contributed towards vaccine hesitancy in Malaysia including miscommunication between the public and healthcare professionals creating a divide and distrust on the National Immunisation Programme, lack of information on the efficacy and vaccine science towards the public, lack of coordination between the governmental organization to stop the release of false information, particularly created by irresponsible parties to create distrust and fear among the public and uneven vaccine rollout (discrepancies in urban and rural areas) may prove to be the stumbling block for Malaysia to achieve herd immunity threshold.

What can the Malaysian government do? In an attempt to counter the vaccine hesitancy, several strategies must be well-planned to educate and improve confidence among the Malaysian public not only for the current Covid-19 situation but also for future pandemics. These include adapting the specific political, social, cultural and economic contexts of countries to provide a comprehensive campaign on the merits and benefits of vaccination. There three main parties that must work together towards this countering approach are the government, community and individuals. One good immediate step that can be taken is to have an interactive forum between the health care professionals and the public both in urban and rural areas to vaccine educate the public which can help to remove the misconceptions with appropriate clarifications from the relevant people.

Conclusively, we are in the midst of one of the worst pandemics in our history of mankind. Our only salvation from this disease is vaccine. Period. And the only way to stop more variants/mutants from appearing is by vaccinating as many people as we can until we reach herd immunity threshold as explained above. All vaccines work! All the current vaccines in the market prevent serious illness/hospitalization/death from Covid-19 – 100%. We simply can not afford the time to choose the vaccine we want as the clock is ticking every second as hundreds die every day to this debilitating disease!

Dr Vinod is a Senior Lecturer at the Jeffrey Cheah School of Medicine & Health Sciences at MUM and a virologist expert who has trained in Monash & Mount Sinai New York.

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