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Sinovac vaccine trial on Bangladeshi health workers

Published : Monday, 28 September, 2020 at 12:00 AM  Count : 343
Jubayer Rahman

Sinovac vaccine trial on Bangladeshi health workers

Sinovac vaccine trial on Bangladeshi health workers

Vaccine makers, who likely to make the lion portion of profit, agreed not to cut corners in the race of developing Covid-19 vaccines. At least nine leading US and European vaccine developers recently pledged not to use short cut route to seek final approval for the COVID-19 vaccine. We have not heard similar promise from China or Russia vaccine developers. These two are particularly rushing to sell their products not only in China or Russia but also all over the world. This initiative is to get the market faster before any real vaccine comes to the market.

This flagrant move is considered dangerous, especially in the vaccine field because it would not help people rather may increase health risk associated with those types of vaccines since the safety data are not extensively studied or not published to public after expert review. However, in any circumstances, time is knocking at the door what to choose since multiple COVID-19 vaccines will be landed without proper testing, even may not complete proper trials or generate enough data before final approval. So, we need to remain vigilant and follow the health guidelines.
Bangladesh has recently approved Sinovac inactivated vaccine for a phase III trial with a great hope that there will be an easy access to this vaccine for mass people if shows any promise. Unfortunately, the agreement was made only for 100000 free doses and the rest would cost 145 US dollar per dose. The most confusing fact behind this approval that icddr, b pushed was that the second generation vaccines such as DNA/RNA based vaccine candidates have never been used in human and may not be good.

The icddr, b also sold the idea that polio vaccine is an inactivated vaccine and that is why COVID-19 vaccine would be safe and protective. This argument is extremely poor, non-scientific and only used by the business people not by the scientists. Perhaps it happened because government representatives had no knowledge on that vaccine platform and thus gave green signal to Sinovac poor vaccine.

It has been several weeks since government gave permission to have phase III trial of Sinovac vaccine trial in Bangladeshi health workers. Unfortunately, this trial has not been planned in the context of Bangladeshi people because of the following questions that are not considered:

1. Who could be the volunteers and what is the scientific rationale behind that?
2. Why did icddr, b choose to have only health care workers as the volunteers in the trial?
3. What are the inclusion and exclusion criteria that will distinguish immunity in an individual who already exposed to Covid-19 and cannot be a volunteer in the trial?

Bangladeshi scientists did not develop the Sinovac vaccine. China company Sinovac proposed the trail site and icddr, b showed their interest. It seems that the trial is very poorly designed in terms of the trial participants. In the context of corona infection and hospitalization of corona patients in Bangladesh, there have been more than 10 hospitals exclusively designated for corona patients from the beginning. However, due to lack of testing and proper treatment management people lost trust and became resistant to go to the hospital even under severe CVOID-19 outcomes. Sinovac company is also not ready to provide the vaccine soon for unknown reasons. What is the science behind this selection?
Sinovac vaccine trial on Bangladeshi health workers

Sinovac vaccine trial on Bangladeshi health workers


The scientific judgment against any emergency trial was based on the kinetics of Covid-19 transmission. Initially, transmission was rapid, number of severe Covid-19 cases was very high. Therefore, there was an urgent need to find an intervention for the first-responders who were likely to contract infection faster than anyone. This situation is different now after around 7 months pandemic. Most importantly, many of the first responders are already exposed to the virus and might have developed immunity.

Currently, almost every country in the world is trying to secure a reliable vaccine against Covid-19. In order to do that, few countries are running vaccine trials without any second thoughts. They are welcoming any healthy volunteers to participate in the trial which is not restricted to only health care workers. Phase III trial generally requires 20000-40000 participants to rule out vaccine induced any minor to major safety issues provided that efficacy is not compromised.

icddr, b planned to recruit 4200 healthy, volunteers in the trial as half of the individuals will receive the actual vaccine (inactivated Covid-19) and other half will receive placebo control. This study is supposed to be done as unbiased and coded format, meaning participants and the trial manager should not know who is receiving the actual vaccine or the placebo control. Once the data is generated from the vaccinated individual, an independent group will decode the information to find if the vaccine induces any protective immunity or not.

There are two obvious concerns in this trail that have not been seriously considered:

1. There has been a significant decrease of Covid-19 patients visiting Covid-19 hospitals where the potential health care workers were the target to receive the vaccine. The idea was that doctors or nurses will be immunized by the vaccine and remain protected for long time as they would see Covid-19 patients often. Therefore, it is expected to answer the question in this phase III trial whether vaccine-induced immunity is protecting the health care workers. Is this possible anymore in BD?

2. It is already conceivable that not only health care workers but also many people in this pandemic are simply exposed to the virus and perhaps have Covid-19 specific immunity developed. If this immunity is not pre-checked how would icddr, b scientists inject the Sinovac vaccine to an individual and later claim that there is a difference where Sinovac vaccine-induced immunity only protecting from Covid-19 infection?

Sadly, answering to these above questions is not thought by the icddr, b scientists. It is apparent that the main focus was to get the trial approval by the government. As a scientist, how could someone ignore the facts while scientific data are truly relying on facts and success comes when facts are unveiled? Are we really prepared to check the natural Covid-19 infection-induced immunity after 7 months pandemic?

This is a question of bringing the extensive immunological studies that are urgently needed to do in pre- and post-Covid-19 infection. The biomarkers that could certify any individual whether immune or not, must be from both antibody and cell-mediated immunity arms as evident by the number of key scientific articles recently published.





In this context, few vaccines that are ignoring T cell responses but prioritizing antibody responses still need to check the pre-existing antibody levels in the volunteers before injecting the vaccine for phase-III trial.
Dr Jubayer Rahman is an Immunologist, lives in Maryland, USA



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