Media Magelang -The efficacy rate of each Covid-19 vaccine has often been an endless debate, both for ordinary people and medical experts.
The use of Moderna's Covid-19 vaccine for the third dose (booster) vaccination for health workers in Indonesia has triggered many doubts about the effectiveness of the China-made Sinovac jab.
According to the records of the Indonesian Doctors Association (IDI), 61 doctors died of exposure to Covid-19 during the February-May 2021 period.
The Thai Red Cross Emerging Infectious Diseases Health Science Center and virologists at BIOTEC published a study that the Sinovac vaccine was less effective against the Delta variant, as quoted by Media Magelang from Thai PBS World, 9 July 2021.
Two doses of the Oxford-AstraZeneca vaccine are considered more effective against the Delta variant of Covid-19 with neutralizing antibody levels reaching 50 percent.
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How Covid-19 vaccine made?
Thailand is considering mixing the Sinovac vaccine (which uses an inactivated virus method) with Oxford-AstraZeneca, which uses the Adenovirus platform that engineered the virus into a vaccine that then infects other viruses.
Meanwhile, Pfizer BioNTech and Moderna vaccines use the mRNA (messenger Rna) method.
The mRna-based vaccine will teach and instruct the body's cells to form proteins that can trigger an immune response in the body.
This immune response will produce antibodies that fortify our bodies when infected with the coronavirus.
On the other hand, the Johnson & Johnson (J&J) vaccine modifies the Adenovirus that contains the genetic material found in the coronavirus.
Unlike other types of vaccines, the J&J vaccine requires only one injection.
How effective are the existing Covid-19 vaccines so far?
Based on clinical trials so far, Moderna and Pfizer BioNTech have the highest levels of efficacy, namely 94 percent (14 days after the second dose) and 95 percent (a week after the second dose), respectively.
Meanwhile, J&J has an efficacy rate of 66 percent, 28 days after a single injection.
Then, how to calculate the level of efficacy?
Of course, this is done through clinical trials involving tens of thousands of people. Pfizer BioNTech's clinical trial involved 43,000 people.
They were divided into two: one half were injected with the original vaccine and the other half were injected with a placebo (empty medicine). Then the participants went about their activities as usual and were monitored whether anyone was exposed to Covid-19.
The result was 170 participants were infected with Covid-19. From here, they were then split again. If out of those170 people affected by Covid-19 there were 85 injected with the vaccine and 85 injected with a placebo, the efficacy is zero percent.
If the 170 infected were those who received the empty medicine, it means that the vaccine's efficacy reached 100 percent.
In this trial, out of 170 people, only eight were infected with Covid-19 after receiving the vaccine and the rest received a placebo. So, the efficacy is 95 percent.
Unfortunately, the level of efficacy is not the only benchmark.
Clinical trials of all vaccines of course use the same methods as described above.
But the problem is what the situation was like when the clinical trials were held?
"One of our biggest considerations when looking at these numbers is when the clinical trial was conducted," said microbiologist Deborah Fuller of The University of Washington.
Pfizer BioNTech and Moderna conducted their clinical trials in the summer of 2020 (approximately August to November 2020) when COVID-19 cases in the US have not yet reached its peak.
Meanwhile, J&J conducted clinical trials around October to January/February 2021 where cases were already high and more people were at risk of infection.
In addition, J&J conducted clinical trials in South Africa and Brazil which not only had high cases but also different types of virus strains.
"If you want to compare one vaccine with another, you need to study it in the same clinical trial at the same time with the same requirements" said scientist of John Hopkins University Center for Health Security Amesh Adalja in a video titled Why You Can't Compare Covid-19 Vaccines uploaded on March 20, 2021.
Amesh added that the aim of the vaccine was not to end the pandemic but to tame the virus itself.
The issue of side effects is also often a debate
Just like drugs, vaccines also cause various side effects such as fever, itching, dizziness, or drowsiness. This is called AEFI (Adverse event following immunization).
The use of the AstraZeneca and J&J vaccines was temporarily suspended in the US and several countries due to the risk of blood clots.
In addition, we often hear that in the end people still have to choose the vaccine because each individual's health condition is different from the disease he or she is suffering from.
"I have congenital diseases, namely diabetes, and heart disease. So I chose not to vaccinate with the current one. I was advised to vaccinate with Moderna" said a resident of Central Jakarta who was not named and had just had a heart stent installed in early July 2021.
Then, what is the solution?
Researcher and doctor Dr. Jacob Wesley Ulm, MD, Ph.D. as quoted by Media Magelang said the issue of which type of vaccine is right for people with congenital diseases is still a matter of debate.
"Which vaccine is suitable for people with diabetes, for example? This is not a question with a straightforward answer because although Pfizer BioNTech's level of efficacy is high, it is not clear how it will affect each individual," said the doctor who admitted that he had experienced COVID-19 symptoms at the beginning of the pandemic.
With the faster spread of the Delta variant, for practical purposes, J&J or Sinopharm vaccines could be the option since they do not require extra cold storage such as mRNA vaccines as used for the Pfizer vaccine.
“All of the vaccines on the market have confirmed good safety and efficacy profiles, but their effects and suitability for any given individual with a comorbidity can be difficult to be certain of. Given the rampant, rapid, and widespread dissemination of the dangerous Delta variant, furthermore, considerations of sheer logistics must be taken into account. Thus, vaccines that are easier to manufacture, ship, and store--for example the Sinopharm, J&J, AZ, and Sputnik vaccines, which do not require the ultra-cold storage and delivery of the Biotech-Pfizer and Moderna vaccines--may in practice be better options on a mass scale, even if the mRNA vaccines might be, technically, more efficacious in a given diabetes patient cohort. The same will likely be true of the protein-subunit vaccines--Novavax and Sanofi--when they become available. At this point, given the mounting threat and alarming contagiousness of the Delta variant (B.1.617.2), the goal should be ensuring ample supplies of whatever vaccine is most available,” the expert said.
However, further clinical trials are still needed involving people with comorbidities, such as people with diabetes and other diseases.
In conclusion, the current vaccine is the best to protect us and those around us from being exposed to Covid-19.
The level of efficacy of the Covid-19 vaccine is important but not the only determining factor.***